,oxy-,acetylene ,welding and ,cutting ,electric1 ,forge and ,thermit ,welding ,together with ,related ,methods and ,materials ,used in ,metal ,working ,and ,the ,oxygen ,process for ,removal of ,carbon ,by ,,harold ,p4 ,,manly ,,preface ,in the preparation of this work1 the object has been to cover not only the several processes of welding1 but also those other processes which are so closely allied in method and results as to make them a part of the whole subject of joining metal to metal with the aid of heat4 ,the workman who wishes to handle his trade from start to finish finds that it is necessary to become familiar with certain other operations which precede or follow the actual joining of the metal parts1 the purpose of these operations being to add or retain certain desirable qualities in the materials being handled4 ,for this reason the following subjects have been included3 ,annealing1 tempering1 hardening1 heat treatment and the restoration of steel4 ,in order that the user may understand the underlying principles and the materials employed in this work1 much practical information is given on the uses and characteristics of the various metals2 on the production1 handling and use of the gases and other materials which are a part of the equipment2 and on the tools and accessories for the production and handling of these materials4 ,an examination will show that the greatest usefulness of this book lies in the fact that all necessary information and data has been included in one volume1 making it possible for the workman to use one source for securing a knowledge of both principle and practice1 preparation and finishing of the work1 and both large and small repair work as well as manufacturing methods used in metal working4 ,an effort has been made to eliminate all matter which is not of direct usefulness in practical work1 while including all that those engaged in this trade find necessary4 ,to this end1 the descriptions have been limited to those methods and accessories which are found in actual use today4 ,for the same reason1 the work includes the application of the rules laid down by the insurance underwriters which govern this work as well as instructions for the proper care and handling of the generators1 torches and materials found in the shop4 ,special attention has been given to definite directions for handling the different metals and alloys which must be handled4 ,the instructions have been arranged to form rules which are placed in the order of their use during the work described and the work has been subdivided in such a way that it will be found possible to secure information on any one point desired without the necessity of spending time in other fields4 ,the facts which the expert welder and metalworker finds it most necessary to have readily available have been secured1 and prepared especially for this work1 and those of most general use have been combined with the chapter on welding practice to which they apply4 ,the size of this volume has been kept as small as possible1 but an examination of the alphabetical index will show that the range of subjects and details covered is complete in all respects4 ,this has been accomplished through careful classification of the contents and the elimination of all repetition and all theoretical1 historical and similar matter that is not absolutely necessary4 ,free use has been made of the information given by those manufacturers who are recognized as the leaders in their respective fields1 thus insuring that the work is thoroughly practical and that it represents present day methods and practice4 ,,the ,,author4 ,,contents ,,chapter ,i ,,metals ,,and ,,alloys--,,heat ,,treatment3--,the ,use and ,characteristics of the ,industrial ,alloys and ,metal ,elements--,annealing1 ,hardening1 ,tempering and ,case ,hardening of ,steel ,,chapter ,,ii ,,welding ,,materials3--,production1 ,handling and ,use of the ,gases1 ,oxygen and ,acetylene--,welding ,rods--,fluxes--,supplies and ,fixtures ,,chapter ,,iii ,,acetylene ,,generators3--,generator ,requirements and ,types--,construction--,care and ,operation of ,generators4 ,,chapter ,,iv ,,welding ,,instruments3--,tank and ,regulating ,valves and ,gauges--,high1 ,low and ,medium ,pressure ,torches--,cutting ,torches--,acetylene-,air ,torches ,,chapter ,v ,,oxy-,,acetylene ,,welding ,,practice3--,preparation of ,work--,torch ,practice-- ,control of the ,flame--,welding ,various ,metals and ,alloys--,tables of ,information ,required in ,welding ,operations ,,chapter ,,vi ,,electric ,,welding3--,resistance ,method--,butt1 ,spot and ,lap ,welding--,troubles and ,remedies--,electric ,arc ,welding ,,chapter ,,vii ,,hand ,,forging ,,and ,,welding3--,blacksmithing1 ,forging and ,bending--,forge ,welding ,methods ,,chapter ,,viii ,,soldering1 ,,brazing ,,and ,,thermit ,,welding3--,soldering ,materials and ,practice-- ,brazing--,thermit ,welding ,,chapter ,,ix ,,oxygen ,,process ,,for ,,removal ,,of ,,carbon ,,index ,,oxy-,,acetylene ,,welding ,,and ,,cutting1 ,,electric ,,and ,,thermit ,,welding ,,chapter ,i ,,metals ,,and ,,their ,,alloys--,,heat ,,treatment ,,the ,,metals ,iron4--,iron1 in its pure state1 is a soft1 white1 easily worked metal4 ,it is the most important of all the metallic elements1 and is1 next to aluminum1 the commonest metal found in the earth4 ,mechanically speaking1 we have three kinds of iron3 wrought iron1 cast iron and steel4 ,wrought iron is very nearly pure iron2 cast iron contains carbon and silicon1 also chemical impurities2 and steel contains a definite proportion of carbon1 but in smaller quantities than cast iron4 ,pure iron is never obtained commercially1 the metal always being mixed with various proportions of carbon1 silicon1 sulphur1 phosphorus1 and other elements1 making it more or less suitable for different purposes4 ,iron is magnetic to the extent that it is attracted by magnets1 but it does not retain magnetism itself1 as does steel4 ,iron forms1 with other elements1 many important combinations1 such as its alloys1 oxides1 and sulphates4 ,illustration3 ,figure #a4--,section ,through a ,blast ,furnace ,cast ,iron4--,metallic iron is separated from iron ore in the blast furnace 7,figure #a71 and when allowed to run into moulds is called cast iron4 ,this form is used for engine cylinders and pistons1 for brackets1 covers1 housings and at any point where its brittleness is not objectionable4 ,good cast iron breaks with a gray fracture1 is free from blowholes or roughness1 and is easily machined1 drilled1 etc4 ,cast iron is slightly lighter than steel1 melts at about #b1djj degrees in practice1 is about one-eighth as good an electrical conductor as copper and has a tensile strength of #ac1jjj to #cj1jjj pounds per square inch4 ,its compressive strength1 or resistance to crushing1 is very great4 ,it has excellent wearing qualities and is not easily warped and deformed by heat4 ,chilled iron is cast into a metal mould so that the outside is cooled quickly1 making the surface very hard and difficult to cut and giving great resistance to wear4 ,it is used for making cheap gear wheels and parts that must withstand surface friction4 ,malleable ,cast ,iron4--,this is often called simply malleable iron4 ,it is a form of cast iron obtained by removing much of the carbon from cast iron1 making it softer and less brittle4 ,it has a tensile strength of #be1jjj to #de1jjj pounds per square inch1 is easily machined1 will stand a small amount of bending at a low red heat and is used chiefly in making brackets1 fittings and supports where low cost is of considerable importance4 ,it is often used in cheap constructions in place of steel forgings4 ,the greatest strength of a malleable casting1 like a steel forging1 is in the surface1 therefore but little machining should be done4 ,wrought ,iron4--,this grade is made by treating the cast iron to remove almost all of the carbon1 silicon1 phosphorus1 sulphur1 manganese and other impurities4 ,this process leaves a small amount of the slag from the ore mixed with the wrought iron4 ,wrought iron is used for making bars to be machined into various parts4 ,if drawn through the rolls at the mill once1 while being made1 it is called muck bar2 if rolled twice1 it is called merchant bar 7the commonest kind71 and a still better grade is made by rolling a third time4 ,wrought iron is being gradually replaced in use by mild rolled steels4 ,wrought iron is slightly heavier than cast iron1 is a much better electrical conductor than either cast iron or steel1 has a tensile strength of #dj1jjj to #fj1jjj pounds per square inch and costs slightly more than steel4 ,unlike either steel or cast iron1 wrought iron does not harden when cooled suddenly from a red heat4 ,grades of ,irons4--,the mechanical properties of cast iron differ greatly according to the amount of other materials it contains4 ,the most important of these contained elements is carbon1 which is present to a degree varying from #b to #e-a_/b per cent4 ,when iron containing much carbon is quickly cooled and then broken1 the fracture is nearly white in color and the metal is found to be hard and brittle4 ,when the iron is slowly cooled and then broken the fracture is gray and the iron is more malleable and less brittle4 ,if cast iron contains sulphur or phosphorus1 it will show a white fracture regardless of the rapidity of cooling1 being brittle and less desirable for general work4 ,steel4--,steel is composed of extremely minute particles of iron and carbon1 forming a network of layers and bands4 ,this carbon is a smaller proportion of the metal than found in cast iron1 the percentage being from #c_/aj to #b-a_/b per cent4 ,carbon steel is specified according to the number of points of carbon1 a point being one one-hundredth of one per cent of the weight of the steel4 ,steel may contain anywhere from #cj to #bej points1 which is equivalent to saying1 anywhere from #c_/aj to #b-a_/b per cent1 as above4 ,a #gj-point steel would contain #gj_/ajj of one per cent or #g_/aj of one per cent of carbon by weight4 ,the percentage of carbon determines the hardness of the steel1 also many other qualities1 and its suitability for various kinds of work4 ,the more carbon contained in the steel1 the harder the metal will be1 and1 of course1 its brittleness increases with the hardness4 ,the smaller the grains or particles of iron which are separated by the carbon1 the stronger the steel will be1 and the control of the size of these particles is the object of the science of heat treatment4 ,in addition to the carbon1 steel may contain the following3 ,silicon1 which increases the hardness1 brittleness1 strength and difficulty of working if from #b to #c per cent is present4 ,phosphorus1 which hardens and weakens the metal but makes it easier to cast4 ,three-tenths per cent of phosphorus serves as a hardening agent and may be present in good steel if the percentage of carbon is low4 ,more than this weakens the metal4 ,sulphur1 which tends to make the metal hard and filled with small holes4 ,manganese1 which makes the steel so hard and tough that it can with difficulty be cut with steel tools4 ,its hardness is not lessened by annealing1 and it has great tensile strength4 ,alloy steel has a varying but small percentage of other elements mixed with it to give certain desired qualities4 ,silicon steel and manganese steel are sometimes classed as alloy steels4 ,this subject is taken up in the latter part of this chapter under ,alloys1 where the various combinations and their characteristics are given consideration4 ,steel has a tensile strength varying from #ej1jjj to #cjj1jjj pounds per square inch1 depending on the carbon percentage and the other alloys present1 as well as upon the texture of the grain4 ,steel is heavier than cast iron and weighs about the same as wrought iron4 ,it is about one-ninth as good a conductor of electricity as copper4 ,steel is made from cast iron by three principal processes3 the crucible1 ,bessemer and open hearth4 ,crucible steel is made by placing pieces of iron in a clay or graphite crucible1 mixed with charcoal and a small amount of any desired alloy4 ,the crucible is then heated with coal1 oil or gas fires until the iron melts1 and1 by absorbing the desired elements and giving up or changing its percentage of carbon1 becomes steel4 ,the molten steel is then poured from the crucible into moulds or bars for use4 ,crucible steel may also be made by placing crude steel in the crucibles in place of the iron4 ,this last method gives the finest grade of metal and the crucible process in general gives the best grades of steel for mechanical use4 ,illustration3 ,figure #b4--;,a ,bessemer ,converter ,bessemer steel is made by heating iron until all the undesirable elements are burned out by air blasts which furnish the necessary oxygen4 ,the iron is placed in a large retort called a converter1 being poured1 while at a melting heat1 directly from the blast furnace into the converter4 ,while the iron in the converter is molten1 blasts of air are forced through the liquid1 making it still hotter and burning out the impurities together with the carbon and manganese4 ,these two elements are then restored to the iron by adding spiegeleisen 7an alloy of iron1 carbon and manganese74 ,a converter holds from #e to #be tons of metal and requires about #bj minutes to finish a charge4 ,this makes the cheapest steel4 ,illustration3 ,figure #c4--;,an ,open ,hearth ,furnace ,open hearth steel is made by placing the molten iron in a receptacle while currents of air pass over it1 this air having itself been highly heated by just passing over white hot brick 7,figure4 #c74 ,open hearth steel is considered more uniform and reliable than ,bessemer1 and is used for springs1 bar steel1 tool steel1 steel plates1 etc4 ,aluminum is one of the commonest industrial metals4 ,it is used for gear cases1 engine crank cases1 covers1 fittings1 and wherever lightness and moderate strength are desirable4 ,aluminum is about one-third the weight of iron and about the same weight as glass and porcelain2 it is a good electrical conductor 7about one-half as good as copper72 is fairly strong itself and gives great strength to other metals when alloyed with them4 ,one of the greatest advantages of aluminum is that it will not rust or corrode under ordinary conditions4 ,the granular formation of aluminum makes its strength very unreliable and it is too soft to resist wear4 ,copper is one of the most important metals used in the trades1 and the best commercial conductor of electricity1 being exceeded in this respect only by silver1 which is but slightly better4 ,copper is very malleable and ductile when cold1 and in this state may be easily worked under the hammer4 ,working in this way makes the copper stronger and harder1 but less ductile4 ,copper is not affected by air1 but acids cause the formation of a green deposit called verdigris4 ,copper is one of the best conductors of heat1 as well as electricity1 being used for kettles1 boilers1 stills and wherever this quality is desirable4 ,copper is also used in alloys with other metals1 forming an important part of brass1 bronze1 german silver1 bell metal and gun metal4 ,it is about one-eighth heavier than steel and has a tensile strength of about #be1jjj to #ej1jjj pounds per square inch4 ,lead4--,the peculiar properties of lead1 and especially its quality of showing but little action or chemical change in the presence of other elements1 makes it valuable under certain conditions of use4 ,its principal use is in pipes for water and gas1 coverings for roofs and linings for vats and tanks4 ,it is also used to coat sheet iron for similar uses and as an important part of ordinary solder4 ,lead is the softest and weakest of all the commercial metals1 being very pliable and inelastic4 ,it should be remembered that lead and all its compounds are poisonous when received into the system4 ,lead is more than one-third heavier than steel1 has a tensile strength of only about #b1jjj pounds per square inch1 and is only about one-tenth as good a conductor of electricity as copper4 ,zinc4--,this is a bluish-white metal of crystalline form4 ,it is brittle at ordinary temperatures and becomes malleable at about #bej to #cjj degrees ,fahrenheit1 but beyond this point becomes even more brittle than at ordinary temperatures4 ,zinc is practically unaffected by air or moisture through becoming covered with one of its own compounds which immediately resists further action4 ,zinc melts at low temperatures1 and when heated beyond the melting point gives off very poisonous fumes4 ,the principal use of zinc is as an alloy with other metals to form brass1 bronze1 german silver and bearing metals4 ,it is also used to cover the surface of steel and iron plates1 the plates being then called galvanized4 ,zinc weighs slightly less than steel1 has a tensile strength of #e1jjj pounds per square inch1 and is not quite half as good as copper in conducting electricity4 ,tin resembles silver in color and luster4 ,tin is ductile and malleable and slightly crystalline in form1 almost as heavy as steel1 and has a tensile strength of #d1ejj pounds per square inch4 ,the principal use of tin is for protective platings on household utensils and in wrappings of tin-foil4 ,tin forms an important part of many alloys such as babbitt1 ,britannia metal1 bronze1 gun metal and bearing metals4 ,nickel is important in mechanics because of its combinations with other metals as alloys4 ,pure nickel is grayish-white1 malleable1 ductile and tenacious4 ,it weighs almost as much as steel and1 next to manganese1 is the hardest of metals4 ,nickel is one of the three magnetic metals1 the others being iron and cobalt4 ,the commonest alloy containing nickel is german silver1 although one of its most important alloys is found in nickel steel4 ,nickel is about ten per cent heavier than steel1 and has a tensile strength of #ij1jjj pounds per square inch4 ,platinum4--,this metal is valuable for two reasons3 it is not affected by the air or moisture or any ordinary acid or salt1 and in addition to this property it melts only at the highest temperatures4 ,it is a fairly good electrical conductor1 being better than iron or steel4 ,it is nearly three times as heavy as steel and its tensile strength is #be1jjj pounds per square inch4 ,,alloys ,an alloy is formed by the union of a metal with some other material1 either metal or non-metallic1 this union being composed of two or more elements and usually brought about by heating the substances together until they melt and unite4 ,metals are alloyed with materials which have been found to give to the metal certain characteristics which are desired according to the use the metal will be put to4 ,the alloys of metals are1 almost without exception1 more important from an industrial standpoint than the metals themselves4 ,there are innumerable possible combinations1 the most useful of which are here classed under the head of the principal metal entering into their composition4 ,steel4--,steel may be alloyed with almost any of the metals or elements1 the combinations that have proven valuable numbering more than a score4 ,the principal ones are given in alphabetical order1 as follows3 ,aluminum is added to steel in very small amounts for the purpose of preventing blow holes in castings4 ,boron increases the density and toughness of the metal4 ,bronze1 added by alloying copper1 tin and iron1 is used for gun metal4 ,carbon has already been considered under the head of steel in the section devoted to the metals4 ,carbon1 while increasing the strength and hardness1 decreases the ease of forging and bending and decreases the magnetism and electrical conductivity4 ,high carbon steel can be welded only with difficulty4 ,when the percentage of carbon is low1 the steel is called low carbon or mild steel4 ,this is used for rods and shafts1 and called machine steel4 ,when the carbon percentage is high1 the steel is called high carbon steel1 and it is used in the shop as tool steel4 ,one-tenth per cent of carbon gives steel a tensile strength of #ej1jjj to #fe1jjj pounds per square inch2 two-tenths per cent gives from #fj1jjj to #hj1jjj2 four-tenths per cent gives #gj1jjj to #ajj1jjj1 and six-tenths per cent gives #ij1jjj to #abj1jjj4 ,chromium forms chrome steel1 and with the further addition of nickel is called chrome nickel steel4 ,this increases the hardness to a high degree and adds strength without much decrease in ductility4 ,chrome steels are used for high-speed cutting tools1 armor plate1 files1 springs1 safes1 dies1 etc4 ,manganese has been mentioned under ,steel4 ,its alloy is much used for high-speed cutting tools1 the steel hardening when cooled in the air and being called self-hardening4 ,molybdenum is used to increase the hardness to a high degree and makes the steel suitable for high-speed cutting and gives it self-hardening properties4 ,nickel1 with which is often combined chromium1 increases the strength1 springiness and toughness and helps to prevent corrosion4 ,silicon has already been described4 ,it suits the metal for use in high-speed tools4 ,silver added to steel has many of the properties of nickel4 ,tungsten increases the hardness without making the steel brittle4 ,this makes the steel well suited for gas engine valves as it resists corrosion and pitting4 ,chromium and manganese are often used in combination with tungsten when high-speed cutting tools are made4 ,vanadium as an alloy increases the elastic limit1 making the steel stronger1 tougher and harder4 ,it also makes the steel able to stand much bending and vibration4 ,copper4--,the principal copper alloys include brass1 bronze1 german silver and gun metal4 ,brass is composed of approximately one-third zinc and two-thirds copper4 ,it is used for bearings and bushings where the speeds are slow and the loads rather heavy for the bearing size4 ,it also finds use in washers1 collars and forms of brackets where the metal should be non-magnetic1 also for many highly finished parts4 ,brass is about one-third as good an electrical conductor as copper1 is slightly heavier than steel and has a tensile strength of #ae1jjj pounds when cast and about #ge1jjj to #ajj1jjj pounds when drawn into wire4 ,bronze is composed of copper and tin in various proportions1 according to the use to which it is to be put4 ,there will always be from six-tenths to nine-tenths of copper in the mixture4 ,bronze is used for bearings1 bushings1 thrust washers1 brackets and gear wheels4 ,it is heavier than steel1 about #a_/ae as good an electrical conductor as pure copper and has a tensile strength of #cj1jjj to #fj1jjj pounds4 ,aluminum bronze1 composed of copper1 zinc and aluminum has high tensile strength combined with ductility and is used for parts requiring this combination4 ,bearing bronze is a variable material1 its composition and proportion depending on the maker and the use for which it is designed4 ,it usually contains from #ge to #he per cent of copper combined with one or more elements1 such as tin1 zinc1 antimony and lead4 ,white metal is one form of bearing bronze containing over #hj per cent of zinc together with copper1 tin1 antimony and lead4 ,another form is made with nearly #ij per cent of tin combined with copper and antimony4 ,gun metal bronze is made from #ij per cent copper with #aj per cent of tin and is used for heavy bearings1 brackets and highly finished parts4 ,phosphor bronze is used for very strong castings and bearings4 ,it is similar to gun metal bronze1 except that about #a-a_/b per cent of phosphorus has been added4 ,manganese bronze contains about #a per cent of manganese and is used for parts requiring great strength while being free from corrosion4 ,german silver is made from #fj per cent of copper with #bj per cent each of zinc and nickel4 ,its high electrical resistance makes it valuable for regulating devices and rheostats4 ,tin is the principal part of babbitt and solder4 ,a commonly used babbitt is composed of #hi per cent tin1 #h per cent antimony and #c per cent of copper4 ,a grade suitable for repairing is made from #hj per cent of lead and #bj per cent antimony4 ,this last formula should not be used for particular work or heavy loads1 being more suitable for spacers4 ,innumerable proportions of metals are marketed under the name of babbitt4 ,solder is made from #ej per cent tin and #ej per cent lead1 this grade being called half-and-half4 ,hard solder is made from two-thirds tin and one-third lead4 ,aluminum forms many different alloys1 giving increased strength to whatever metal it unites with4 ,aluminum brass is composed of approximately #fe per cent copper1 #cj per cent zinc and #e per cent aluminum4 ,it forms a metal with high tensile strength while being ductile and malleable4 ,aluminum zinc is suitable for castings which must be stiff and hard4 ,nickel aluminum has a tensile strength of #dj1jjj pounds per square inch4 ,magnalium is a silver-white alloy of aluminum with from #e to #bj per cent of magnesium1 forming a metal even lighter than aluminum and strong enough to be used in making high-speed gasoline engines4 ,,heat ,,treatment ,,of ,,steel ,the processes of heat treatment are designed to suit the steel for various purposes by changing the size of the grain in the metal1 therefore the strength2 and by altering the chemical composition of the alloys in the metal to give it different physical properties4 ,heat treatment1 as applied in ordinary shop work1 includes the three processes of annealing1 hardening and tempering1 each designed to accomplish a certain definite result4 ,all of these processes require that the metal treated be gradually brought to a certain predetermined degree of heat which shall be uniform throughout the piece being handled and1 from this point1 cooled according to certain rules1 the selection of which forms the difference in the three methods4 ,annealing4--,this is the process which relieves all internal strains and distortion in the metal and softens it so that it may more easily be cut1 machined or bent to the required form4 ,in some cases annealing is used only to relieve the strains1 this being the case after forging or welding operations have been performed4 ,in other cases it is only desired to soften the metal sufficiently that it may be handled easily4 ,in some cases both of these things must be accomplished1 as after a piece has been forged and must be machined4 ,no matter what the object1 the procedure is the same4 ,the steel to be annealed must first be heated to a dull red4 ,this heating should be done slowly so that all parts of the piece have time to reach the same temperature at very nearly the same time4 ,the piece may be heated in the forge1 but a much better way is to heat in an oven or furnace of some type where the work is protected against air currents1 either hot or cold1 and is also protected against the direct action of the fire4 ,illustration3 ,figure #d4--;,a ,gaspipe ,annealing ,oven ,probably the simplest of all ovens for small tools is made by placing a piece of ordinary gas pipe in the fire 7,figure #d71 and heating until the inside of the pipe is bright red4 ,parts placed in this pipe1 after one end has been closed1 may be brought to the desired heat without danger of cooling draughts or chemical change from the action of the fire4 ,more elaborate ovens may be bought which use gas1 fuel oils or coal to produce the heat and in which the work may be placed on trays so that the fire will not strike directly on the steel being treated4 ,if the work is not very important1 it may be withdrawn from the fire or oven1 after heating to the desired point1 and allowed to cool in the air until all traces of red have disappeared when held in a dark place4 ,the work should be held where it is reasonably free from cold air currents4 ,if1 upon touching a pine stick to the piece being annealed1 the wood does not smoke1 the work may then be cooled in water4 ,better annealing is secured and harder metal may be annealed if the cooling is extended over a number of hours by placing the work in a bed of non-heat-conducting material1 such as ashes1 charred bone1 asbestos fibre1 lime1 sand or fire clay4 ,it should be well covered with the heat retaining material and allowed to remain until cool4 ,cooling may be accomplished by allowing the fire in an oven or furnace to die down and go out1 leaving the work inside the oven with all openings closed4 ,the greater the time taken for gradual cooling from the red heat1 the more perfect will be the results of the annealing4 ,while steel is annealed by slow cooling1 copper or brass is annealed by bringing to a low red heat and quickly plunging into cold water4 ,hardening4--,steel is hardened by bringing to a proper temperature1 slowly and evenly as for annealing1 and then cooling more or less quickly1 according to the grade of steel being handled4 ,the degree of hardening is determined by the kind of steel1 the temperature from which the metal is cooled and the temperature and nature of the bath into which it is plunged for cooling4 ,steel to be hardened is often heated in the fire until at some heat around #fjj to #gjj degrees is reached1 then placed in a heating bath of molten lead1 heated mercury1 fused cyanate of potassium1 etc41 the heating bath itself being kept at the proper temperature by fires acting on it4 ,while these baths have the advantage of heating the metal evenly and to exactly the temperature desired throughout without any part becoming over or under heated1 their disadvantages consist of the fact that their materials and the fumes are poisonous in most all cases1 and if not poisonous1 are extremely disagreeable4 ,the degree of heat that a piece of steel must be brought to in order that it may be hardened depends on the percentage of carbon in the steel4 ,the greater the percentage of carbon1 the lower the heat necessary to harden4 ,illustration3 ,figure #e4--;,cooling the ,test ,bar for ,hardening ,to find the proper heat from which any steel must be cooled1 a simple test may be carried out provided a sample of the steel1 about six inches long can be secured4 ,one end of this test bar should be heated almost to its melting point1 and held at this heat until the other end just turns red4 ,now cool the piece in water by plunging it so that both ends enter at the same time 7,figure #e71 that is1 hold it parallel with the surface of the water when plunged in4 ,this serves the purpose of cooling each point along the bar from a different heat4 ,when it has cooled in the water remove the piece and break it at short intervals1 about #a_/b inch1 along its length4 ,the point along the test bar which was cooled from the best possible temperature will show a very fine smooth grain and the piece cannot be cut by a file at this point4 ,it will be necessary to remember the exact color of that point when taken from the fire1 making another test if necessary1 and heat all pieces of this same steel to this heat4 ,it will be necessary to have the cooling bath always at the same temperature1 or the results cannot be alike4 ,while steel to be hardened is usually cooled in water1 many other liquids may be used4 ,if cooled in strong brine1 the heat will be extracted much quicker1 and the degree of hardness will be greater4 ,a still greater degree of hardness is secured by cooling in a bath of mercury4 ,care should be used with the mercury bath1 as the fumes that arise are poisonous4 ,should toughness be desired1 without extreme hardness1 the steel may be cooled in a bath of lard oil1 neatsfoot oil or fish oil4 ,to secure a result between water and oil1 it is customary to place a thick layer of oil on top of water4 ,in cooling1 the piece will pass through the oil first1 thus avoiding the sudden shock of the cold water1 yet producing a degree of hardness almost as great as if the oil were not used4 ,it will1 of course1 be necessary to make a separate test for each cooling medium used4 ,if the fracture of the test piece shows a coarse grain1 the steel was too hot at that point2 if the fracture can be cut with a file1 the metal was not hot enough at that point4 ,when hardening carbon tool steel its heat should be brought to a cherry red1 the exact degree of heat depending on the amount of carbon and the test made1 then plunged into water and held there until all hissing sound and vibration ceases4 ,brine may be used for this purpose2 it is even better than plain water4 ,as soon as the hissing stops1 remove the work from the water or brine and plunge in oil for complete cooling4 ,illustration3 ,figure #f4--;,cooling the ,tool for ,tempering ,in hardening high-speed tool steel1 or air hardening steels1 the tool should be handled as for carbon steel1 except that after the body reaches a cherry red1 the cutting point must be quickly brought to a white heat1 almost melting1 so that it seems ready for welding4 ,then cool in an oil bath or in a current of cool air4 ,hardening of copper1 brass and bronze is accomplished by hammering or working them while cold4 ,tempering is the process of making steel tough after it has been hardened1 so that it will hold a cutting edge and resist cracking4 ,tempering makes the grain finer and the metal stronger4 ,it does not affect the hardness1 but increases the elastic limit and reduces the brittleness of the steel4 ,in that tempering is usually performed immediately after hardening1 it might be considered as a continuation of the former process4 ,the work or tool to be tempered is slowly heated to a cherry red and the cutting end is then dipped into water to a depth of #a_/b to #c_/d inch above the point 7,figure #f74 ,as soon as the point cools1 still leaving the tool red above the part in water1 remove the work from the bath and quickly rub the end with a fine emery cloth4 ,as the heat from the uncooled part gradually heats the point again1 the color of the polished portion changes rapidly4 ,when a certain color is reached1 the tool should be completely immersed in the water until cold4 ,for lathe1 planer1 shaper and slotter tools1 this color should be a light straw4 ,reamers and taps should be cooled from an ordinary straw color4 ,drills1 punches and wood working tools should have a brown color4 ,blue or light purple is right for cold chisels and screwdrivers4 ,dark blue should be reached for springs and wood saws4 ,darker colors than this1 ranging through green and gray1 denote that the piece has reached its ordinary temper1 that is1 it is partially annealed4 ,after properly hardening a spring by dipping in lard or fish oil1 it should be held over a fire while still wet with the oil4 ,the oil takes fire and burns off1 properly tempering the spring4 ,remember that self-hardening steels must never be dipped in water1 and always remember for all work requiring degrees of heat1 that the more carbon1 the less heat4 ,case ,hardening4--,this is a process for adding more carbon to the surface of a piece of steel1 so that it will have good wear-resisting qualities1 while being tough and strong on the inside4 ,it has the effect of forming a very hard and durable skin on the surface of soft steel1 leaving the inside unaffected4 ,the simplest way1 although not the most efficient1 is to heat the piece to be case hardened to a red heat and then sprinkle or rub the part of the surface to be hardened with potassium ferrocyanide4 ,this material is a deadly poison and should be handled with care4 ,allow the cyanide to fuse on the surface of the metal and then plunge into water1 brine or mercury4 ,repeating the process makes the surface harder and the hard skin deeper each time4 ,another method consists of placing the piece to be hardened in a bed of powdered bone 7bone which has been burned and then powdered7 and cover with more powdered bone1 holding the whole in an iron tray4 ,now heat the tray and bone with the work in an oven to a bright red heat for #cj minutes to an hour and then plunge the work into water or brine4 ,,chapter ,,ii ,,oxy-,,acetylene ,,welding ,,and ,,cutting ,,materials ,welding4--,oxy-acetylene welding is an autogenous welding process1 in which two parts of the same or different metals are joined by causing the edges to melt and unite while molten without the aid of hammering or compression4 ,when cool1 the parts form one piece of metal4 ,the oxy-acetylene flame is made by mixing oxygen and acetylene gases in a special welding torch or blowpipe1 producing1 when burned1 a heat of #f1cjj degrees1 which is more than twice the melting temperature of the common metals4 ,this flame1 while being of intense heat1 is of very small size4 ,cutting4--,the process of cutting metals with the flame produced from oxygen and acetylene depends on the fact that a jet of oxygen directed upon hot metal causes the metal itself to burn away with great rapidity1 resulting in a narrow slot through the section cut4 ,the action is so fast that metal is not injured on either side of the cut4 ,carbon ,removal4--,this process depends on the fact that carbon will burn and almost completely vanish if the action is assisted with a supply of pure oxygen gas4 ,after the combustion is started with any convenient flame1 it continues as long as carbon remains in the path of the jet of oxygen4 ,materials4--,for the performance of the above operations we require the two gases1 oxygen and acetylene1 to produce the flames2 rods of metal which may be added to the joints while molten in order to give the weld sufficient strength and proper form1 and various chemical powders1 called fluxes1 which assist in the flow of metal and in doing away with many of the impurities and other objectionable features4 ,instruments4--,to control the combustion of the gases and add to the convenience of the operator a number of accessories are required4 ,the pressure of the gases in their usual containers is much too high for their proper use in the torch and we therefore need suitable valves which allow the gas to escape from the containers when wanted1 and other specially designed valves which reduce the pressure4 ,hose1 composed of rubber and fabric1 together with suitable connections1 is used to carry the gas to the torch4 ,the torches for welding and cutting form a class of highly developed instruments of the greatest accuracy in manufacture1 and must be thoroughly understood by the welder4 ,tables1 stands and special supports are provided for holding the work while being welded1 and in order to handle the various metals and allow for their peculiarities while heated use is made of ovens and torches for preheating4 ,the operator requires the protection of goggles1 masks1 gloves and appliances which prevent undue radiation of the heat4 ,torch ,practice4--,the actual work of welding and cutting requires preliminary preparation in the form of heat treatment for the metals1 including preheating1 annealing and tempering4 ,the surfaces to be joined must be properly prepared for the flame1 and the operation of the torches for best results requires careful and correct regulation of the gases and the flame produced4 ,finally1 the different metals that are to be welded require special treatment for each one1 depending on the physical and chemical characteristics of the material4 ,it will thus be seen that the apparently simple operations of welding and cutting require special materials1 instruments and preparation on the part of the operator and it is a proved fact that failures1 which have been attributed to the method1 are really due to lack of these necessary qualifications4 ,,oxygen ,oxygen1 the gas which supports the rapid combustion of the acetylene in the torch flame1 is one of the elements of the air4 ,it is the cause and the active agent of all combustion that takes place in the atmosphere4 ,oxygen was first discovered as a separate gas in #aggd1 when it was produced by heating red oxide of mercury and was given its present name by the famous chemist1 ,lavoisier4 ,oxygen is prepared in the laboratory by various methods1 these including the heating of chloride of lime and peroxide of cobalt mixed in a retort1 the heating of chlorate of potash1 and the separation of water into its elements1 hydrogen and oxygen1 by the passage of an electric current4 ,while the last process is used on a large scale in commercial work1 the others are not practical for work other than that of an experimental or temporary nature4 ,this gas is a colorless1 odorless1 tasteless element4 ,it is sixteen times as heavy as the gas hydrogen when measured by volume under the same temperature and pressure4 ,under all ordinary conditions oxygen remains in a gaseous form1 although it turns to a liquid when compressed to #d1djj pounds to the square inch and at a temperature of #bbj below zero4 ,oxygen unites with almost every other element1 this union often taking place with great heat and much light1 producing flame4 ,steel and iron will burn rapidly when placed in this gas if the combustion is started with a flame of high heat playing on the metal4 ,if the end of a wire is heated bright red and quickly plunged into a jar containing this gas1 the wire will burn away with a dazzling light and be entirely consumed except for the molten drops that separate themselves4 ,this property of oxygen is used in oxy-acetylene cutting of steel4 ,the combination of oxygen with other substances does not necessarily cause great heat1 in fact the combination may be so slow and gradual that the change of temperature can not be noticed4 ,an example of this slow combustion1 or oxidation1 is found in the conversion of iron into rust as the metal combines with the active gas4 ,the respiration of human beings and animals is a form of slow combustion and is the source of animal heat4 ,it is a general rule that the process of oxidation takes place with increasing rapidity as the temperature of the body being acted upon rises4 ,iron and steel at a red heat oxidize rapidly with the formation of a scale and possible damage to the metal4 ,air4--,atmospheric air is a mixture of oxygen and nitrogen with traces of carbonic acid gas and water vapor4 ,twenty-one per cent of the air1 by volume1 is oxygen and the remaining seventy-nine per cent is the inactive gas1 nitrogen4 ,but for the presence of the nitrogen1 which deadens the action of the other gas1 combustion would take place at a destructive rate and be beyond human control in almost all cases4 ,these two gases exist simply as a mixture to form the air and are not chemically combined4 ,it is therefore a comparatively simple matter to separate them with the processes now available4 ,water4--,water is a combination of oxygen and hydrogen1 being composed of exactly two volumes of hydrogen to one volume of oxygen4 ,if these two gases be separated from each other and then allowed to mix in these proportions they unite with explosive violence and form water4 ,water itself may be separated into the gases by any one of several means1 one making use of a temperature of #b1bjj to bring about this separation4 ,illustration3 ,figure #g4--,obtaining ,oxygen by ,electrolysis ,the easiest way to separate water into its two parts is by the process called electrolysis 7,figure #g74 ,water1 with which has been mixed a small quantity of acid1 is placed in a vat through the walls of which enter the platinum tipped ends of two electrical conductors1 one positive and the other negative4 ,tubes are placed directly above these wire terminals in the vat1 one tube being over each electrode and separated from each other by some distance4 ,with the passage of an electric current from one wire terminal to the other1 bubbles of gas rise from each and pass into the tubes4 ,the gas that comes from the negative terminal is hydrogen and that from the positive pole is oxygen1 both gases being almost pure if the work is properly conducted4 ,this method produces electrolytic oxygen and electrolytic hydrogen4 ,the ,liquid ,air ,process4--,while several of the foregoing methods of securing oxygen are successful as far as this result is concerned1 they are not profitable from a financial standpoint4 ,a process for separating oxygen from the nitrogen in the air has been brought to a high state of perfection and is now supplying a major part of this gas for oxy-acetylene welding4 ,it is known as the ,linde process and the gas is distributed by the ,linde ,air ,products ,company from its plants and warehouses located in the large cities of the country4 ,the air is first liquefied by compression1 after which the gases are separated and the oxygen collected4 ,the air is purified and then compressed by successive stages in powerful machines designed for this purpose until it reaches a pressure of about #c1jjj pounds to the square inch4 ,the large amount of heat produced is absorbed by special coolers during the process of compression4 ,the highly compressed air is then dried and the temperature further reduced by other coolers4 ,the next point in the separation is that at which the air is introduced into an apparatus called an interchanger and is allowed to escape through a valve1 causing it to turn to a liquid4 ,this liquid air is sprayed onto plates and as it falls1 the nitrogen return to its gaseous state and leaves the oxygen to run to the bottom of the container4 ,this liquid oxygen is then allowed to return to a gas and is stored in large gasometers or tanks4 ,the oxygen gas is taken from the storage tanks and compressed to approximately #a1hjj pounds to the square inch1 under which pressure it is passed into steel cylinders and made ready for delivery to the customer4 ,this oxygen is guaranteed to be ninety-seven per cent pure4 ,another process1 known as the ,hildebrandt process1 is coming into use in this country4 ,it is a later process and is used in ,germany to a much greater extent than the ,linde process4 ,the ,superior ,oxygen ,co4 has secured the ,american rights and has established several plants4 ,oxygen ,cylinders4--,two sizes of cylinders are in use1 one containing #ajj cubic feet of gas when it is at atmospheric pressure and the other containing #bej cubic feet under similar conditions4 ,the cylinders are made from one piece of steel and are without seams4 ,these containers are tested at double the pressure of the gas contained to insure safety while handling4 ,one hundred cubic feet of oxygen weighs nearly nine pounds 7#h4iba71 and therefore the cylinders will weigh practically nine pounds more when full than after emptying1 if of the #ajj cubic feet size4 ,the large cylinders weigh about eighteen and one-quarter pounds more when full than when empty1 making approximately #bab pounds empty and #bcj pounds full4 ,the following table gives the number of cubic feet of oxygen remaining in the cylinders according to various gauge pressures from an initial pressure of #a1hjj pounds4 ,the amounts given are not exactly correct as this would necessitate lengthy calculations which would not make great enough difference to affect the practical usefulness of the table3 ,cylinder of #ajj ,cu4 ,ft4 ,capacity at #fh ,fahr4 ,gauge ,volume ,gauge ,volume ,pressure ,remaining ,pressure ,remaining #ahjj #ajj #gjj #ci #afbj #ij #ejj #bh #addj #hj #cjj #ag #abfj #gj #ajj #f #ajhj #fj #ah #a #ijj #ej #i #a_/b ,cylinder of #bej ,cu4 ,ft4 ,capacity at #fh ,fahr4 ,gauge ,volume ,gauge ,volume ,pressure ,remaining ,pressure ,remaining #ahjj #bej #gjj #ig #afbj #bbe #ejj #gj #addj #bjj #cjj #db #abfj #age #ajj #ae #ajhj #aej #ah #h #ijj #abe #i #a-a_/d ,the temperature of the cylinder affects the pressure in a large degree1 the pressure increasing with a rise in temperature and falling with a fall in temperature4 ,the variation for a #ajj cubic foot cylinder at various temperatures is given in the following tabulation3 ,at #aej ,fahr444444444444444444444444 #bjij pounds4 ,at #ajj ,fahr444444444444444444444444 #aiab pounds4 ,at #hj ,fahr444444444444444444444444 #ahdd pounds4 ,at #fh ,fahr444444444444444444444444 #ahjj pounds4 ,at #ej ,fahr444444444444444444444444 #agcf pounds4 ,at #cb ,fahr444444444444444444444444 #afgb pounds4 ,at #j ,fahr444444444444444444444444 #aeeh pounds4 ,at -#aj ,fahr444444444444444444444444 #aebb pounds4 ,chlorate of ,potash ,method4--,in spite of its higher cost and the inferior gas produced1 the chlorate of potash method of producing oxygen is used to a limited extent when it is impossible to secure the gas in cylinders4 ,illustration3 ,figure #h4--,oxygen from ,chlorate of ,potash ,an iron retort 7,figure #h7 is arranged to receive about fifteen pounds of chlorate of potash mixed with three pounds of manganese dioxide1 after which the cylinder is closed with a tight cap1 clamped on4 ,this retort is carried above a burner using fuel gas or other means of generating heat and this burner is lighted after the chemical charge is mixed and compressed in the tube4 ,the generation of gas commences and the oxygen is led through water baths which wash and cool it before storing in a tank connected with the plant4 ,from this tank the gas is compressed into portable cylinders at a pressure of about #cjj pounds to the square inch for use as required in welding operations4 ,each pound of chlorate of potash liberates about three cubic feet of oxygen1 and taking everything into consideration1 the cost of gas produced in this way is several times that of the purer product secured by the liquid air process4 ,these chemical generators are oftentimes a source of great danger1 especially when used with or near the acetylene gas generator1 as is sometimes the case with cheap portable outfits4 ,their use should not be tolerated when any other method is available1 as the danger from accident alone should prohibit the practice except when properly installed and cared for away from other sources of combustible gases4 ,,acetylene ,in #ahfb a chemist1 ,woehler1 announced the discovery of the preparation of acetylene gas from calcium carbide1 which he had made by heating to a high temperature a mixture of charcoal with an alloy of zinc and calcium4 ,his product would decompose water and yield the gas4 ,for nearly thirty years these substances were neglected1 with the result that acetylene was practically unknown1 and up to #ahib an acetylene flame was seen by very few persons and its possibilities were not dreamed of4 ,with the development of the modern electric furnace the possibility of calcium carbide as a commercial product became known4 ,in the above year1 ,thomas ,l4 ,willson1 an electrical engineer of ,spray1 ,north ,carolina1 was experimenting in an attempt to prepare metallic calcium1 for which purpose he employed an electric furnace operating on a mixture of lime and coal tar with about ninety-five horse power4 ,the result was a molten mass which became hard and brittle when cool4 ,this apparently useless product was discarded and thrown in a nearby stream1 when1 to the astonishment of onlookers1 a large volume of gas was immediately liberated1 which1 when ignited1 burned with a bright and smoky flame and gave off quantities of soot4 ,the solid material proved to be calcium carbide and the gas acetylene4 ,thus1 through the incidental study of a by-product1 and as the result of an accident1 the possibilities in carbide were made known1 and in the spring of #ahie the first factory in the world for the production of this substance was established by the ,willson ,aluminum ,company4 ,when water and calcium carbide are brought together an action takes place which results in the formation of acetylene gas and slaked lime4 ,,carbide ,calcium carbide is a chemical combination of the elements carbon and calcium1 being dark brown1 black or gray with sometimes a blue or red tinge4 ,it looks like stone and will only burn when heated with oxygen4 ,calcium carbide may be preserved for any length of time if protected from the air1 but the ordinary moisture in the atmosphere gradually affects it until nothing remains but slaked lime4 ,it always possesses a penetrating odor1 which is not due to the carbide itself but to the fact that it is being constantly affected by moisture and producing small quantities of acetylene gas4 ,this material is not readily dissolved by liquids1 but if allowed to come in contact with water1 a decomposition takes place with the evolution of large quantities of gas4 ,carbide is not affected by shock1 jarring or age4 ,a pound of absolutely pure carbide will yield five and one-half cubic feet of acetylene4 ,absolute purity cannot be attained commercially1 and in practice good carbide will produce from four and one-half to five cubic feet for each pound used4 ,carbide is prepared by fusing lime and carbon in the electric furnace under a heat in excess of #f1jjj degrees ,fahrenheit4 ,these materials are among the most difficult to melt that are known4 ,lime is so infusible that it is frequently employed for the materials of crucibles in which the highest melting metals are fused1 and for the pencils in the calcium light because it will stand extremely high temperatures4 ,carbon is the material employed in the manufacture of arc light electrodes and other electrical appliances that must stand extreme heat4 ,yet these two substances are forced into combination in the manufacture of calcium carbide4 ,it is the excessively high temperature attainable in the electric furnace that causes this combination and not any effect of the electricity other than the heat produced4 ,a mixture of ground coke and lime is introduced into the furnace through which an electric arc has been drawn4 ,the materials unite and form an ingot of very pure carbide surrounded by a crust of less purity4 ,the poorer crust is rejected in breaking up the mass into lumps which are graded according to their size4 ,the largest size is #b by #c-a_/b inches and is called lump1 a medium size is #a_/b by #b inches and is called egg1 an intermediate size for certain types of generators is #c_/h by #a-a_/d inches and called nut1 and the finely crushed pieces for use in still other types of generators are #a_/ab by #a_/d inch in size and are called quarter4 ,instructions as to the size best suited to different generators are furnished by the makers of those instruments4 ,these sizes are packed in air-tight sheet steel drums containing #ajj pounds each4 ,the ,union ,carbide ,company of ,chicago and ,new ,york1 operating under patents1 manufactures and distributes the supply of calcium carbide for the entire ,united ,states4 ,plants for this manufacture are established at ,niagara ,falls1 ,new ,york1 and ,sault ,ste4 ,marie1 ,michigan4 ,this company maintains a system of warehouses in more than one hundred and ten cities1 where large stocks of all sizes are carried4 ,the ,national ,board of ,fire ,underwriters gives the following rules for the storage of carbide3 ,calcium carbide in quantities not to exceed six hundred pounds may be stored1 when contained in approved metal packages not to exceed one hundred pounds each1 inside insured property1 provided that the place of storage be dry1 waterproof and well ventilated and also provided that all but one of the packages in any one building shall be sealed and that seals shall not be broken so long as there is carbide in excess of one pound in any other unsealed package in the building4 ,calcium carbide in quantities in excess of six hundred pounds must be stored above ground in detached buildings1 used exclusively for the storage of calcium carbide1 in approved metal packages1 and such buildings shall be constructed to be dry1 waterproof and well ventilated4 ,properties of ,acetylene4--,this gas is composed of twenty-four parts of carbon and two parts of hydrogen by weight and is classed with natural gas1 petroleum1 etc41 as one of the hydrocarbons4 ,this gas contains the highest percentage of carbon known to exist in any combination of this form and it may therefore be considered as gaseous carbon4 ,carbon is the fuel that is used in all forms of combustion and is present in all fuels from whatever source or in whatever form4 ,acetylene is therefore the most powerful of all fuel gases and is able to give to the torch flame in welding the highest temperature of any flame4 ,acetylene is a colorless and tasteless gas1 possessed of a peculiar and penetrating odor4 ,the least trace in the air of a room is easily noticed1 and if this odor is detected about an apparatus in operation1 it is certain to indicate a leakage of gas through faulty piping1 open valves1 broken hose or otherwise4 ,this leakage must be prevented before proceeding with the work to be done4 ,all gases which burn in air will1 when mixed with air previous to ignition1 produce more or less violent explosions1 if fired4 ,to this rule acetylene is no exception4 ,one measure of acetylene and twelve and one-half of air are required for complete combustion2 this is therefore the proportion for the most perfect explosion4 ,this is not the only possible mixture that will explode1 for all proportions from three to thirty per cent of acetylene in air will explode with more or less force if ignited4 ,the igniting point of acetylene is lower than that of coal gas1 being about #ijj degrees ,fahrenheit as against eleven hundred degrees for coal gas4 ,the gas issuing from a torch will ignite if allowed to play on the tip of a lighted cigar4 ,it is still further true that acetylene1 at some pressures1 greater than normal1 has under most favorable conditions for the effect1 been found to explode2 yet it may be stated with perfect confidence that under no circumstances has anyone ever secured an explosion in it when subjected to pressures not exceeding fifteen pounds to the square inch4 ,although not exploded by the application of high heat1 acetylene is injured by such treatment4 ,it is partly converted1 by high heat1 into other compounds1 thus lessening the actual quantity of the gas1 wasting it and polluting the rest by the introduction of substances which do not belong there4 ,these compounds remain in part with the gas1 causing it to burn with a persistent smoky flame and with the deposit of objectionable tarry substances4 ,where the gas is generated without undue rise of temperature these difficulties are avoided4 ,purification of ,acetylene4--,impurities in this gas are caused by impurities in the calcium carbide from which it is made or by improper methods and lack of care in generation4 ,impurities from the material will be considered first4 ,impurities in the carbide may be further divided into two classes3 those which exert no action on water and those which act with the water to throw off other gaseous products which remain in the acetylene4 ,those impurities which exert no action on the water consist of coke that has not been changed in the furnace and sand and some other substances which are harmless except that they increase the ash left after the acetylene has been generated4 ,an analysis of the gas coming from a typical generator is as follows3 ,per cent ,acetylene 44444444444444444444444444444444 #ii4cf ,oxygen 44444444444444444444444444444444444 4#jh ,nitrogen 444444444444444444444444444444444 4#aa ,hydrogen 444444444444444444444444444444444 4#jf ,sulphuretted ,hydrogen 44444444444444444444 4#ag ,phosphoretted ,hydrogen 4444444444444444444 4#jd ,ammonia 4444444444444444444444444444444444 4#aj ,silicon ,hydride 44444444444444444444444444 4#jc ,carbon ,monoxide 44444444444444444444444444 4#ja ,methane 4444444444444444444444444444444444 4#jd ,the oxygen1 nitrogen1 hydrogen1 methane and carbon monoxide are either harmless or are present in such small quantities as to be neglected4 ,the phosphoretted hydrogen and silicon hydride are self-inflammable gases when exposed to the air1 but their quantity is so very small that this possibility may be dismissed4 ,the ammonia and sulphuretted hydrogen are almost entirely dissolved by the water used in the gas generator4 ,the surest way to avoid impure gas is to use high-grade calcium carbide in the generator and the carbide of ,american manufacture is now so pure that it never causes trouble4 ,the first and most important purification to which the gas is subjected is its passage through the body of water in the generator as it bubbles to the top4 ,it is then filtered through felt to remove the solid particles of lime dust and other impurities which float in the gas4 ,further purification to remove the remaining ammonia1 sulphuretted hydrogen and phosphorus containing compounds is accomplished by chemical means4 ,if this is considered necessary it can be easily accomplished by readily available purifying apparatus which can be attached to any generator or inserted between the generator and torch outlets4 ,the following mixtures have been used4 ,heratol1 a solution of chromic acid or sulphuric acid absorbed in porous earth4 ,acagine1 a mixture of bleaching powder with fifteen per cent of lead chromate4 ,puratylene1 a mixture of bleaching powder and hydroxide of lime1 made very porous1 and containing from eighteen to twenty per cent of active chlorine4 ,frankoline1 a mixture of cuprous and ferric chlorides dissolved in strong hydrochloric acid absorbed in infusorial earth4 ,a test for impure acetylene gas is made by placing a drop of ten per cent solution of silver nitrate on a white blotter and holding the paper in a stream of gas coming from the torch tip4 ,blackening of the paper in a short length of time indicates impurities4 ,acetylene in ,tanks4--,acetylene is soluble in water to a very limited extent1 too limited to be of practical use4 ,there is only one liquid that possesses sufficient power of containing acetylene in solution to be of commercial value1 this being the liquid acetone4 ,acetone is produced in various ways1 oftentimes from the distillation of wood4 ,it is a transparent1 colorless liquid that flows with ease4 ,it boils at #acc ,fahrenheit1 is inflammable and burns with a luminous flame4 ,it has a peculiar but rather agreeable odor4 ,acetone dissolves twenty-four times its own bulk of acetylene at ordinary atmospheric pressure4 ,if this pressure is increased to two atmospheres1 #ad4g pounds above ordinary pressure1 it will dissolve just twice as much of the gas and for each atmosphere that the pressure is increased it will dissolve as much more4 ,if acetylene be compressed above fifteen pounds per square inch at ordinary temperature without first being dissolved in acetone a danger is present of self-ignition4 ,this danger1 while practically nothing at fifteen pounds1 increases with the pressure until at forty atmospheres it is very explosive4 ,mixed with acetone1 the gas loses this dangerous property and is safe for handling and transportation4 ,as acetylene is dissolved in the liquid the acetone increases its volume slightly so that when the gas has been drawn out of a closed tank a space is left full of free acetylene4 ,this last difficulty is removed by first filling the cylinder or tank with some porous material1 such as asbestos1 wood charcoal1 infusorial earth1 etc4 ,asbestos is used in practice and by a system of packing and supporting the absorbent material no space is left for the free gas1 even when the acetylene has been completely withdrawn4 ,the acetylene is generated in the usual way and is washed1 purified and dried4 ,great care is used to make the gas as free as possible from all impurities and from air4 ,the gas is forced into containers filled with acetone as described and is compressed to one hundred and fifty pounds to the square inch4 ,from these tanks it is transferred to the smaller portable cylinders for consumers' use4 ,the exact volume of gas remaining in a cylinder at atmospheric temperature may be calculated if the weight of the cylinder empty is known4 ,one pound of the gas occupies #ac4f cubic feet1 so that if the difference in weight between the empty cylinder and the one considered be multiplied by #ac4f4 the result will be the number of cubic feet of gas contained4 ,the cylinders contain from #ajj to #ejj cubic feet of acetylene under pressure4 ,they cannot be filled with the ordinary type of generator as they require special purifying and compressing apparatus1 which should never be installed in any building where other work is being carried on1 or near other buildings which are occupied1 because of the danger of explosion4 ,dissolved acetylene is manufactured by the ,prest-,o-,lite ,company1 the ,commercial ,acetylene ,company and the ,searchlight ,gas ,company and is distributed from warehouses in various cities4 ,these tanks should not be discharged at a rate per hour greater than one-seventh of their total capacity1 that is1 from a tank of #ajj cubic feet capacity1 the discharge should not be more than fourteen cubic feet per hour4 ,if discharge is carried on at an excessive rate the acetone is drawn out with the gas and reduces the heat of the welding flame4 ,for this reason welding should not be attempted with cylinders designed for automobile and boat lighting4 ,when the work demands a greater delivery than one of the larger tanks will give1 two or more tanks may be connected with a special coupler such as may be secured from the makers and distributers of the gas4 ,these couplers may be arranged for two1 three1 four or five tanks in one battery by removing the plugs on the body of the coupler and attaching additional connecting pipes4 ,the coupler body carries a pressure gauge and the valve for controlling the pressure of the gas as it flows to the welding torches4 ,the following capacities should be provided for3 ,acetylene ,consumption ,combined ,capacity of of ,torches per ,hour ,cylinders in ,use ,up to #ae feet44444444444444444444444#ajj cubic feet #af to #cj feet44444444444444444444444#bjj cubic feet #ca to #de feet44444444444444444444444#cjj cubic feet #df to #fj feet44444444444444444444444#djj cubic feet #fa to #ge feet44444444444444444444444#ejj cubic feet ,,welding ,,rods ,the best welding cannot be done without using the best grade of materials1 and the added cost of these materials over less desirable forms is so slight when compared to the quality of work performed and the waste of gases with inferior supplies1 that it is very unprofitable to take any chances in this respect4 ,the makers of welding equipment carry an assortment of supplies that have been standardized and that may be relied upon to produce the desired result when properly used4 ,the safest plan is to secure this class of material from the makers4 ,welding rods1 or welding sticks1 are used to supply the additional metal required in the body of the weld to replace that broken or cut away and also to add to the joint whenever possible so that the work may have the same or greater strength than that found in the original piece4 ,a rod of the same material as that being welded is used when both parts of the work are the same4 ,when dissimilar metals are to be joined rods of a composition suited to the work are employed4 ,these filling rods are required in all work except steel of less than #af gauge4 ,alloy iron rods are used for cast iron4 ,these rods have a high silicon content1 the silicon reacting with the carbon in the iron to produce a softer and more easily machined weld than would otherwise be the case4 ,these rods are often made so that they melt at a slightly lower point than cast iron4 ,this is done for the reason that when the part being welded has been brought to the fusing heat by the torch1 the filling material can be instantly melted in without allowing the parts to cool4 ,the metal can be added faster and more easily controlled4 ,rods or wires of ,norway iron are used for steel welding in almost all cases4 ,the purity of this grade of iron gives a homogeneous1 soft weld of even texture1 great ductility and exceptionally good machining qualities4 ,for welding heavy steel castings1 a rod of rolled carbon steel is employed4 ,for working on high carbon steel1 a rod of the steel being welded must be employed and for alloy steels1 such as nickel1 manganese1 vanadium1 etc41 special rods of suitable alloy composition are preferable4 ,aluminum welding rods are made from this metal alloyed to give the even flowing that is essential4 ,aluminum is one of the most difficult of all the metals to handle in this work and the selection of the proper rod is of great importance4 ,brass is filled with brass wire when in small castings and sheets4 ,for general work with brass castings1 manganese bronze or ,tobin bronze may be used4 ,bronze is welded with manganese bronze or ,tobin bronze1 while copper is filled with copper wire4 ,these welding rods should always be used to fill the weld when the thickness of material makes their employment necessary1 and additional metal should always be added at the weld when possible as the joint cannot have the same strength as the original piece if made or dressed off flush with the surfaces around the weld4 ,this is true because the metal welded into the joint is a casting and will never have more strength than a casting of the material used for filling4 ,great care should be exercised when adding metal from welding rods to make sure that no metal is added at a point that is not itself melted and molten when the addition is made4 ,when molten metal is placed upon cooler surfaces the result is not a weld but merely a sticking together of the two parts without any strength in the joint4 ,,fluxes ,difficulty would be experienced in welding with only the metal and rod to work with because of the scale that forms on many materials under heat1 the oxides of other metals and the impurities found in almost all metals4 ,these things tend to prevent a perfect joining of the metals and some means are necessary to prevent their action4 ,various chemicals1 usually in powder form1 are used to accomplish the result of cleaning the weld and making the work of the operator less difficult4 ,they are called fluxes4 ,a flux is used to float off physical impurities from the molten metal2 to furnish a protecting coating around the weld2 to assist in the removal of any objectionable oxide of the metals being handled2 to lower the temperature at which the materials flow2 to make a cleaner weld and to produce a better quality of metal in the finished work4 ,the flux must be of such composition that it will accomplish the desired result without introducing new difficulties4 ,they may be prepared by the operator in many cases or may be secured from the makers of welding apparatus1 the same remarks applying to their quality as were made regarding the welding rods1 that is1 only the best should be considered4 ,the flux used for cast iron should have a softening effect and should prevent burning of the metal4 ,in many cases it is possible and even preferable to weld cast iron without the use of a flux1 and in any event the smaller the quantity used the better the result should be4 ,flux should not be added just before the completion of the work because the heat will not have time to drive the added elements out of the metal or to incorporate them with the metal properly4 ,aluminum should never be welded without using a flux because of the oxide formed4 ,this oxide1 called alumina1 does not melt until a heat of #e1jjj ,fahrenheit is reached1 four times the heat needed to melt the aluminum itself4 ,it is necessary that this oxide be broken down or dissolved so that the aluminum may have a chance to flow together4 ,copper is another metal that requires a flux because of its rapid oxidation under heat4 ,while the flux is often thrown or sprinkled along the break while welding1 much better results will be obtained by dipping the hot end of the welding rod into the flux whenever the work needs it4 ,sufficient powder will stick on the end of the rod for all purposes1 and with some fluxes too much will adhere4 ,care should always be used to avoid the application of excessive flux1 as this is usually worse than using too little4 ,,supplies ,,and ,,fixtures ,goggles4--,the oxy-acetylene torch should not be used without the protection to the eyes afforded by goggles4 ,these not only relieve unnecessary strain1 but make it much easier to watch the exact progress of the work with the molten metal4 ,the difficulty of protecting the sight while welding is even greater than when cutting metal with the torch4 ,acetylene gives a light which is nearest to sunlight of any artificial illuminant4 ,but for the fact that this gas light gives a little more green and less blue in its composition1 it would be the same in quality and practically the same in intensity4 ,this light from the gas is almost absent during welding1 being lost with the addition of the extra oxygen needed to produce the welding heat4 ,the light that is dangerous comes from the molten metal which flows under the torch at a bright white heat4 ,goggles for protection against this light and the heat that goes with it may be secured in various tints1 the darker glass being for welding and the lighter for cutting4 ,those having frames in which the metal parts do not touch the flesh directly are most desirable because of the high temperature reached by these parts4 ,gloves4--,while not as necessary as are the goggles1 gloves are a convenience in many cases4 ,those in which leather touches the hands directly are really of little value as the heat that protection is desired against makes the leather so hot that nothing is gained in comfort4 ,gloves are made with asbestos cloth1 which are not open to this objection in so great a degree4 ,illustration3 ,figure #i4--;,frame for ,welding ,stand ,tables and ,stands4--,tables for holding work while being welded 7,figure #i7 are usually made from lengths of angle steel welded together4 ,the top should be rectangular1 about two feet wide and two and one-half feet long4 ,the legs should support the working surface at a height of thirty-two to thirty-six inches from the floor4 ,metal lattice work may be fastened or laid in the top framework and used to support a layer of firebrick bound together with a mixture of one-third cement and two-thirds fireclay4 ,the piece being welded is braced and supported on this table with pieces of firebrick so that it will remain stationary during the operation4 ,holders for supporting the tanks of gas may be made or purchased in forms that rest directly on the floor or that are mounted on wheels4 ,these holders are quite useful where the floor or ground is very uneven4 ,hose4--,all permanent lines from tanks and generators to the torches are made with piping rigidly supported1 but the short distance from the end of the pipe line to the torch itself is completed with a flexible hose so that the operator may be free in his movements while welding4 ,an accident through which the gases mix in the hose and are ignited will burst this part of the equipment1 with more or less painful results to the person handling it4 ,for that reason it is well to use hose with great enough strength to withstand excessive pressure4 ,a poor grade of hose will also break down inside and clog the flow of gas1 both through itself and through the parts of the torch4 ,to avoid outside damage and cuts this hose is sometimes encased with coiled sheet metal4 ,hose may be secured with a bursting strength of more than #a1jjj pounds to the square inch4 ,many operators prefer to distinguish between the oxygen and acetylene lines by their color and to allow this1 red is used for the oxygen and black for acetylene4 ,other ,materials4--,sheet asbestos and asbestos fibre in flakes are used to cover parts of the work while preparing them for welding and during the operation itself4 ,the flakes and small pieces that become detached from the large sheets are thrown into a bin where the completed small work is placed to allow slow and even cooling while protected by the asbestos4 ,asbestos fibre and also ordinary fireclay are often used to make a backing or mould into a form that may be placed behind aluminum and some other metals that flow at a low heat and which are accordingly difficult to handle under ordinary methods4 ,this forms a solid mould into which the metal is practically cast as melted by the torch so that the desired shape is secured without danger of the walls of metal breaking through and flowing away4 ,carbon blocks and rods are made in various shapes and sizes so that they may be used to fill threaded holes and other places that it is desired to protect during welding4 ,these may be secured in rods of various diameters up to one inch and in blocks of several different dimensions4 ,,chapter ,,iii ,,acetylene ,,generators ,acetylene generators used for producing the gas from the action of water on calcium carbide are divided into three principal classes according to the pressure under which they operate4 ,low pressure generators are designed to operate at one pound or less per square inch4 ,medium pressure systems deliver the gas at not to exceed fifteen pounds to the square inch while high pressure types furnish gas above fifteen pounds per square inch4 ,high pressure systems are almost unknown in this country1 the medium pressure type being often referred to as high pressure4 ,another important distinction is formed by the method of bringing the carbide and water together4 ,the majority of those now in use operate by dropping small quantities of carbide into a large volume of water1 allowing the generated gas to bubble up through the water before being collected above the surface4 ,this type is known as the carbide to water generator4 ,a less used type brings a measured and small quantity of water to a comparatively large body of the carbide1 the gas being formed and collected from the chamber in which the action takes place4 ,this is called the water to carbide type4 ,another way of expressing the difference in feed is that of designating the two types as carbide feed for the former and water feed for the latter4 ,a further division of the carbide to water machines is made by mentioning the exact method of feeding the carbide4 ,one type1 called gravity feed operates by allowing the carbide to escape and fall by the action of its own weight1 or gravity2 the other type1 called forced feed1 includes a separate mechanism driven by power4 ,this mechanism feeds definite amounts of the carbide to the water as required by the demands on the generator4 ,the action of either feed is controlled by the withdrawal of gas from the generator1 the aim being to supply sufficient carbide to maintain a nearly constant supply4 ,generator ,requirements4--,the qualities of a good generator are outlined as follows3 ,footnote3 ,see ,pond's ,calcium ,carbide and ,acetylene4 ,it must allow no possibility of the existence of an explosive mixture in any of its parts at any time4 ,it is not enough to argue that a mixture1 even if it exists1 cannot be exploded unless kindled4 ,it is necessary to demand that a dangerous mixture can at no time be formed1 even if the machine is tampered with by an ignorant person4 ,the perfect machine must be so constructed that it shall be impossible at any time1 under any circumstances1 to blow it up4 ,it must insure cool generation4 ,since this is a relative term1 all machines being heated somewhat during the generation of gas1 this amounts to saying that a machine must heat but little4 ,a pound of carbide decomposed by water develops the same amount of heat under all circumstances1 but that heat can be allowed to increase locally to a high point1 or it can be equalized by water so that no part of the material becomes heated enough to do damage4 ,it must be well constructed4 ,a good generator does not need1 perhaps1 to be built like a watch1 but it should be solid1 substantial and of good material4 ,it should be built for service1 to last and not simply to sell2 anything short of this is to be avoided as unsafe and unreliable4 ,it must be simple4 ,the more complicated the machine the sooner it will get out of order4 ,understand your generator4 ,know what is inside of it and beware of an apparatus1 however attractive its exterior1 whose interior is filled with pipes and tubes1 valves and diaphragms whose functions you do not perfectly understand4 ,it should be capable of being cleaned and recharged and of receiving all other necessary attention without loss of gas1 both for economy's sake1 and more particularly to avoid danger of fire4 ,it should require little attention4 ,all machines have to be emptied and recharged periodically2 but the more this process is simplified and the more quickly this can be accomplished1 the better4 ,it should be provided with a suitable indicator to designate how low the charge is in order that the refilling may be done in good season4 ,it should completely use up the carbide1 generating the maximum amount of gas4 ,overheating4--,a large amount of heat is liberated when acetylene gas is formed from the union of calcium carbide and water4 ,overheating during this process1 that is to say1 an intense local heat rather than a large amount of heat well distributed1 brings about the phenomenon of polymerization1 converting the gas1 or part of it1 into oily matters1 which can do nothing but harm4 ,this tarry mass coming through the small openings in the torches causes them to become partly closed and alters the proportions of the gases to the detriment of the welding flame4 ,the only remedy for this trouble is to avoid its cause and secure cool generation4 ,overheating can be detected by the appearance of the sludge remaining after the gas has been made4 ,discoloration1 yellow or brown1 shows that there has been trouble in this direction and the resultant effects at the torches may be looked for4 ,the abundance of water in the carbide to water machines effects this cooling naturally and is a characteristic of well designed machines of this class4 ,it has been found best and has practically become a fundamental rule of generation that a gallon of water must be provided for each pound of carbide placed in the generator4 ,with this ratio and a generator large enough for the number of torches to be supplied1 little trouble need be looked for with overheating4 ,water to ,carbide ,generators4--,it is1 of course1 much easier to obtain a measured and regular flow of water than to obtain such a flow of any solid substance1 especially when the solid substance is in the form of lumps1 as is carbide ,this fact led to the use of a great many water-feed generators for all classes of work1 and this type is still in common use for the small portable machines1 such1 for instance1 as those used on motor cars for the lamps4 ,the water-feed machine is not1 however1 favored for welding plants1 as is the carbide feed1 in spite of the greater difficulties attending the handling of the solid material4 ,a water-feed generator is made up of the gas producing part and a holder for the acetylene after it is made4 ,the carbide is held in a tray formed of a number of small compartments so that the charge in each compartment is nearly equal to that in each of the others4 ,the water is allowed to flow into one of these compartments in a volume sufficient to produce the desired amount of gas and the carbide is completely used from this one division4 ,the water then floods the first compartment and finally overflows into the next one1 where the same process is repeated4 ,after using the carbide in this division1 it is flooded in turn and the water passing on to those next in order1 uses the entire charge of the whole tray4 ,these generators are charged with the larger sizes of carbide and are easily taken care of4 ,the residue is removed in the tray and emptied1 making the generator ready for a fresh supply of carbide4 ,carbide to ,water ,generators4--,this type also is made up of two principal parts1 the generating chamber and a gas holder1 the holder being part of the generating chamber or a separate device4 ,the generator 7,figure #aj7 contains a hopper to receive the charge of carbide and is fitted with the feeding mechanism to drop the proper amount of carbide into the water as required by the demands of the torches4 ,the charge of carbide is of one of the smaller sizes1 usually nut or quarter4 ,feed ,mechanisms4--,the device for dropping the carbide into the water is the only part of the machine that is at all complicated4 ,this complication is brought about by the necessity of controlling the mass of carbide so that it can never be discharged into the water at an excessive rate1 feeding it at a regular rate and in definite amounts1 feeding it positively whenever required and shutting off the feed just as positively when the supply of gas in the holder is enough for the immediate needs4 ,illustration3 ,figure #aj4--;,carbide to ,water ,generator4 ,a4 ,feed motor weight2 ,b4 ,carbide feed motor2 ,c4 ,carbide hopper2 ,d4 ,water for gas generation2 ,e4 ,agitator for loosening residuum2 ,f4 ,water seal in gas bell2 ,g4 ,filter2 ,h4 ,hydraulic ,valve2 ,j4 ,motor control levers4 ,the charge of carbide is unavoidably acted upon by the water vapor in the generator and will in time become more or less pasty and sticky4 ,this is more noticeable if the generator stands idle for a considerable length of time ,this condition imposes another duty on the feeding mechanism2 that is1 the necessity of self-cleaning so that the carbide1 no matter in what condition1 cannot prevent the positive action of this part of the device1 especially so that it cannot prevent the supply from being stopped at the proper time4 ,the gas holder is usually made in the bell form so that the upper portion rises and falls with the addition to or withdrawal from the supply of gas in the holder4 ,the rise and fall of this bell is often used to control the feed mechanism because this movement indicates positively whether enough gas has been made or that more is required4 ,as the bell lowers it sets the feed mechanism in motion1 and when the gas passing into the holder has raised the bell a sufficient distance1 the movement causes the feed mechanism to stop the fall of carbide into the water4 ,in practice1 the movement of this part of the holder is held within very narrow limits4 ,gas ,holders4--,no matter how close the adjustment of the feeding device1 there will always be a slight amount of gas made after the fall of carbide is stopped1 this being caused by the evolution of gas from the carbide with which water is already in contact4 ,this action is called after generation and the gas holder in any type of generator must provide sufficient capacity to accommodate this excess gas4 ,as a general rule the water to carbide generator requires a larger gas holder than the carbide to water type because of the greater amount of carbide being acted upon by the water at any one time1 also because the surface of carbide presented to the moist air within the generating chamber is greater with this type4 ,freezing4--,because of the rather large body of water contained in any type of generator1 there is always danger of its freezing and rendering the device inoperative unless placed in a temperature above the freezing point of the water4 ,it is1 of course1 dangerous and against the insurance rules to place a generator in the same room with a fire of any kind1 but the room may be heated by steam or hot water coils from a furnace in another building or in another part of the same building4 ,when the generator is housed in a separate structure the walls should be made of materials or construction that prevents the passage of heat or cold through them to any great extent4 ,this may be accomplished by the use of hollow tile or concrete blocks or by any other form of double wall providing air spaces between the outer and inner facings4 ,the space between the parts of the wall may be filled with materials that further retard the loss of heat if this is necessary under the conditions prevailing4 ,residue ,from ,generators4--,the sludge remaining in the carbide to water generator may be drawn off into the sewer if the piping is run at a slant great enough to give a fall that carries the whole quantity1 both water and ash1 away without allowing settling and consequent clogging4 ,generators are provided with agitators which are operated to stir the ash up with the water so that the whole mass is carried off when the drain cock is opened4 ,if sewer connections cannot be made in such a way that the ash is entirely carried away1 it is best to run the liquid mass into a settling basin outside of the building4 ,this should be in the form of a shallow pit which will allow the water to pass off by soaking into the ground and by evaporation1 leaving the comparatively dry ash in the pit4 ,this ash which remains is essentially slaked lime and can often be disposed of to more or less advantage to be used in mortar1 whitewash1 marking paths and any other use for which slaked lime is suited4 ,the disposition of the ash depends entirely on local conditions4 ,an average analysis of this ash is as follows3 ,sand44444444444444444444444 #a4aj per cent4 ,carbon444444444444444444444 #b4gb ,oxide of iron and alumina44 #b4gg ,lime44444444444444444444444 #fd4jf ,water and carbonic acid4444 #bi4ce ------ #ajj4jj ,,generator ,,construction ,the water for generating purposes is carried in the large tank-like compartment directly below the carbide chamber4 ,see ,figure #aa4 ,this water compartment is filled through a pipe of such a height that the water level cannot be brought above the proper point or else the water compartment is provided with a drain connection which accomplishes this same result by allowing an excess to flow away4 ,the quantity of water depends on the capacity of the generator inasmuch as there must be one gallon for each pound of carbide required4 ,the generator should be of sufficient capacity to furnish gas under working conditions from one charge of carbide to all torches installed for at least five hours continuous use4 ,after calculating the withdrawal of the whole number of torches according to the work they are to do for this period of five hours the proper generator capacity may be found on the basis of one cubic foot of gas per hour for each pound of carbide4 ,thus if the torches were to use sixty cubic feet of gas per hour1 five hours would call for three hundred cubic feet and a three hundred pound generator should be installed4 ,generators are rated according to their carbide capacity in pounds4 ,charging4--,the carbide capacity of the generator should be great enough to furnish a continuous supply of gas for the maximum operating time1 basing the quantity of gas generated on four and one-half cubic feet from each pound of lump carbide and on four cubic feet from each pound of quarter1 intermediate sizes being in proportion4 ,generators are built in such a way that it is impossible for the acetylene to escape from the gas holding compartment during the recharging process4 ,this is accomplished 7#a7 by connecting the water inlet pipe opening with a shut off valve in such a way that the inlet cannot be uncovered or opened without first closing the shut off valve with the same movement of the operator2 7#b7 by incorporating an automatic or hydraulic one-way valve so that this valve closes and acts as a check when the gas attempts to flow from the holder back to the generating chamber1 or by any other means that will positively accomplish this result4 ,in generators having no separate gas holding chamber but carrying the supply in the same compartment in which it is generated1 the gas contained under pressure is allowed to escape through vent pipes into the outside air before recharging with carbide4 ,as in the former case1 the parts are so interlocked that it is impossible to introduce carbide or water without first allowing the escape of the gas in the generator4 ,it is required by the insurance rules that the entire change of carbide while in the generator be held in such a way that it may be entirely removed without difficulty in case the necessity should arise4 ,generators should be cleaned and recharged at regular stated intervals4 ,this work should be done during daylight hours only and likewise all repairs should be made at such a time that artificial light is not needed4 ,where it is absolutely necessary to use artificial light it should be provided only by incandescent electric lamps enclosed in gas tight globes4 ,in charging generating chambers the old ash and all residue must first be cleaned out and the operator should be sure that no drain or other pipe has become clogged4 ,the generator should then be filled with the required amount of water4 ,in charging carbide feed machines be careful not to place less than a gallon of water in the water compartment for each pound of carbide to be used and the water must be brought to1 but not above1 the proper level as indicated by the mark or the maker's instructions4 ,the generating chamber must be filled with the proper amount of water before any attempt is made to place the carbide in its holder4 ,this rule must always be followed4 ,it is also necessary that all automatic water seals and valves1 as well as any other water tanks1 be filled with clean water at this time4 ,never recharge with carbide without first cleaning the generating chamber and completely refilling with clean water4 ,never test the generator or piping for leaks with any flame1 and never apply flame to any open pipe or at any point other than the torch1 and only to the torch after it has a welding or cutting nozzle attached4 ,never use a lighted match1 lamp1 candle1 lantern1 cigar or any open flame near a generator4 ,failure to observe these precautions is liable to endanger life and property4 ,operation and ,care of ,generators4--,the following instructions apply especially to the ,davis ,bournonville pressure generator1 illustrated in ,figure #aa4 ,the motor feed mechanism is illustrated in ,figure #ab4 ,before filling the machine1 the cover should be removed and the hopper taken out and examined to see that the feeding disc revolves freely2 that no chains have been displaced or broken1 and that the carbide displacer itself hangs barely free of the feeding disc when it is revolved4 ,after replacing the cover1 replace the bolts and tighten them equally1 a little at a time all around the circumference of the cover--not screwing tight in one place only4 ,do not screw the cover down any more than is necessary to make a tight fit4 ,to charge the generator1 proceed as follows3 ,open the vent valve by turning the handle which extends over the filling tube until it stands at a right angle with the generator4 ,open the valve in the water filling pipe1 and through this fill with water until it runs out of the overflow pipe of the drainage chamber1 then close the valve in the water filling pipe and vent valve4 ,remove the carbide filling plugs and fill the hopper with #a-a_/dx#c_/h carbide 7nut size74 ,then replace the plugs and the safety-locking lever chains4 ,now rewind the motor weight4 ,run the pressure up to about five pounds by raising the controlling diaphragm valve lever by hand 7,figure #ab1 lever marked ,e74 ,then raise the blow-off lever1 allowing the gas to blow off until the gauge shows about two pounds2 this to clear the generator of air mixture4 ,then run the pressure up to about eight pounds by raising the controlling valve lever ,e1 or until this controlling lever rests against the upper wing of the fan governor1 and prevents operation of the feed motor4 ,after this is done1 the motor will operate automatically as the gas is consumed4 ,illustration3 ,figure #aa4--,pressure ,generator 7,davis ,bournonville74 ,a1 ,feed motor weight2 ,b1 ,carbide feed motor2 ,c1 ,motor ,control diaphragm2 ,d1 ,carbide hopper2 ,e1 ,carbide feed disc2 ,f1 ,overflow pipe2 ,g1 ,overflow pipe seal2 ,h1 ,overflow pipe valve2 ,j1 ,filling funnel2 ,k1 ,hydraulic valve2 ,l1 ,expansion chamber2 ,m1 ,escape pipe2 ,n1 ,feed pipe2 ,o1 ,agitator for residuum2 ,p1 ,residuum valve2 ,q1 ,water level ,illustration3 ,figure #ab4--;,feed ,mechanism of ,pressure ,generator ,should the pressure rise much above the blow-off point1 the safety controlling diaphragm valve will operate and throw the safety clutch in interference and thus stop the motor4 ,this interference clutch will then have to be returned to its former position before the motor will operate1 but cannot be replaced before the pressure has been reduced below the blow-off point4 ,the parts of the feed mechanism illustrated in ,figure #ab are as follows3 ,a1 motor drum for weight cable4 ,b1 carbide filling plugs4 ,c1 chains for connecting safety locking lever of motor to pins on the top of the carbide plugs4 ,d1 interference clutch of motor4 ,e1 lever on feed controlling diaphragm valve4 ,f1 lever of interference controlling diaphragm valve that operates interference clutch4 ,g1 feed controlling diaphragm valve4 ,h1 diaphragm valve controlling operation of interference clutch4 ,i1 interference pin to engage emergency clutch4 ,j1 main shaft driving carbide feeding disc4 ,y1 safety locking lever4 ,recharging ,generator4--,turn the agitator handle rapidly for several revolutions1 and then open the residuum valve1 having five or six pounds gas pressure on the machine4 ,if the carbide charge has been exhausted and the motor has stopped1 there is generally enough carbide remaining in the feeding disc that can be shaken off1 and fed by running the motor to obtain some pressure in the generator4 ,the desirability of discharging the residuum with some gas pressure is because the pressure facilitates the discharge and at the same time keeps the generator full of gas1 preventing air mixture to a great extent4 ,as soon as the pressure is relieved by the withdrawal of the residuum1 the vent valve should be opened1 as if the pressure is maintained until all of the residuum is discharged gas would escape through the discharge valve4 ,having opened the vent pipe valve and relieved the pressure1 open the valve in the water filling tube4 ,close the residuum valve1 then run in several gallons of water and revolve the agitator1 after which draw out the remaining residuum2 then again close the residuum valve and pour in water until it discharges from the overflow pipe of the drainage chamber4 ,it is desirable in filling the generator to pour the water in rapidly enough to keep the filling pipe full of water1 so that air will not pass in at the same time4 ,after the generator is cleaned and filled with water1 fill with carbide and proceed in the same manner as when first charging4 ,carbide ,feed ,mechanism4--,any form of carbide to water machine should be so designed that the carbide never falls directly from its holder into the water1 but so that it must take a more or less circuitous path4 ,this should be true1 no matter what position the mechanism is in4 ,one of the commonest types of forced feed machine carries the carbide in a hopper with slanting sides1 this hopper having a large opening in the bottom through which the carbide passes to a revolving circular plate4 ,as the pieces of carbide work out toward the edge of the plate under the influence of the mass behind them1 they are thrown off into the water by small stationary fins or plows which are in such a position that they catch the pieces nearest the edges and force them off as the plate revolves4 ,this arrangement1 while allowing a free passage for the carbide1 prevents an excess from falling should the machine stop in any position4 ,when1 as is usually the case1 the feed mechanism is actuated by the rise or fall of pressure in the generator or of the level of some part of the gas holder1 it must be built in such a way that the feeding remains inoperative as long as the filling opening on the carbide holder remains open4 ,the feed of carbide should always be shut off and controlled so that under no condition can more gas be generated than could be cared for by the relief valve provided4 ,it is necessary also to have the feed mechanism at least ten inches above the surface of the water so that the parts will never become clogged with damp lime dust4 ,motor ,feed4--,the feed mechanism itself is usually operated by power secured from a slowly falling weight which1 through a cable1 revolves a drum4 ,to this drum is attached suitable gearing for moving the feed parts with sufficient power and in the way desired4 ,this part1 called the motor1 is controlled by two levers1 one releasing a brake and allowing the motor to operate the feed1 the other locking the gearing so that no more carbide will be dropped into the water4 ,these levers are moved either by the quantity of gas in the holder or by the pressure of the gas1 depending on the type of machine4 ,with a separate gas holder1 such as used with low pressure systems1 the levers are operated by the rise and fall of the bell of the holder or gasometer1 alternately starting and stopping the motor as the bell falls and rises again4 ,medium pressure generators are provided with a diaphragm to control the feed motor4 ,this diaphragm is carried so that the pressure within the generator acts on one side while a spring1 whose tension is under the control of the operator1 acts on the other side4 ,the diaphragm is connected to the brake and locking device on the motor in such a way that increasing the tension on the spring presses the diaphragm and moves a rod that releases the brake and starts the feed4 ,the gas pressure1 increasing with the continuation of carbide feed1 acts on the other side and finally overcomes the pressure of the spring tension1 moving the control rod the other way and stopping the motor and carbide feed4 ,this spring tension is adjusted and checked with the help of a pressure gauge attached to the generating chamber4 ,gravity ,feed4--,this type of feed differs from the foregoing in that the carbide is simply released and is allowed to fall into the water without being forced to do so4 ,any form of valve that is sufficiently powerful in action to close with the carbide passing through is used and is operated by the power secured from the rise and fall of the gas holder bell4 ,when this valve is first opened the carbide runs into the water until sufficient pressure and volume of gas is generated to raise the bell4 ,this movement operates the arm attached to the carbide shut off valve and slowly closes it4 ,a fall of the bell occasioned by gas being withdrawn again opens the valve and more gas is generated4 ,mechanical ,feed4--,the previously described methods of feeding carbide to the water have all been automatic in action and do not depend on the operator for their proper action4 ,some types of large generating plants have a power-driven feed1 the power usually being from some kind of motor other than one operated by a weight1 such as a water motor1 for instance4 ,this motor is started and stopped by the operator when1 in his judgment1 more gas is wanted or enough has been generated4 ,this type of machine1 often called a non-automatic generator1 is suitable for large installations and is attached to a gas holder of sufficient size to hold a day's supply of acetylene4 ,the generator can then be operated until a quantity of gas has been made that will fill the large holder1 or gasometer1 and then allowed to remain idle for some time4 ,gas ,holders4--,the commonest type of gas container is that known as a gasometer4 ,this consists of a circular tank partly filled with water1 into which is lowered another circular tank1 inverted1 which is made enough smaller in diameter than the first one so that three-quarters of an inch is left between them4 ,this upper and inverted portion1 called the bell1 receives the gas from the generator and rises or falls in the bath of water provided in the lower tank as a greater or less amount of gas is contained in it4 ,these holders are made large enough so that they will provide a means of caring for any after generation and so that they maintain a steady and even flow4 ,the generator1 however1 must be of a capacity great enough so that the gas holder will not be drawn on for part of the supply with all torches in operation4 ,that is1 the holder must not be depended on for a reserve supply4 ,the bell of the holder is made so that when full of gas its lower edge is still under a depth of at least nine inches of water in the lower tank4 ,any further rise beyond this point should always release the gas1 or at least part of it1 to the escape pipe so that the gas will under no circumstances be forced into the room from1 between the bell and tank4 ,the bell is guided in its rise and fall by vertical rods so that it will not wedge at any point in its travel4 ,a condensing chamber to receive the water which condenses from the acetylene gas in the holder is usually placed under this part and is provided with a drain so that this water of condensation may be easily removed4 ,filtering4--,a small chamber containing some closely packed but porous material such as felt is placed in the pipe leading to the torch lines4 ,as the acetylene gas passes through this filter the particles of lime dust and other impurities are extracted from it so that danger of clogging the torch openings is avoided as much as possible4 ,the gas is also filtered to a large extent by its passage through the water in the generating chamber1 this filtering or scrubbing often being facilitated by the form of piping through which the gas must pass from the generating chamber into the holder4 ,if the gas passes out of a number of small openings when going into the holder the small bubbles give a better washing than large ones would4 ,piping4--,connections from generators to service pipes should preferably be made with right and left couplings or long thread nipples with lock nuts4 ,if unions are used1 they should be of a type that does not require gaskets4 ,the piping should be carried and supported so that any moisture condensing in the lines will drain back toward the generator and where low points occur they should be drained through tees leading into drip cups which are permanently closed with screw caps or plugs4 ,no pet cocks should be used for this purpose4 ,for the feed pipes to the torch lines the following pipe sizes are recommended4 #c_/h inch pipe4 #bf feet long4 #b cubic feet per hour4 #a_/b inch pipe4 #cj feet long4 #d cubic feet per hour4 #c_/d inch pipe4 #ej feet long4 #ae cubic feet per hour4 #a inch pipe4 #gj feet long4 #bg cubic feet per hour4 #a-a_/d inch pipe4 #ajj feet long4 #ej cubic feet per hour4 #a-a_/b inch pipe4 #aej feet long4 #fe cubic feet per hour4 #b inch pipe4 #bjj feet long4 #abe cubic feet per hour4 #b-a_/b inch pipe4 #cjj feet long4 #aij cubic feet per hour4 #c inch pipe4 #dej feet long4 #cce cubic feet per hour4 ,when drainage is possible into a sewer1 the generator should not be connected directly into the sewer but should first discharge into an open receptacle1 which may in turn be connected to the sewer4 ,no valves or pet cocks should open into the generator room or any other room when it would be possible1 by opening them for draining purposes1 to allow any escape of gas4 ,any condensation must be removed without the use of valves or other working parts1 being drained into closed receptacles4 ,it should be needless to say that all the piping for gas must be perfectly tight at every point in its length4 ,safety ,devices4--,good generators are built in such a way that the operator must follow the proper order of operation in charging and cleaning as well as in all other necessary care4 ,it has been mentioned that the gas pressure is released or shut off before it is possible to fill the water compartment1 and this same idea is carried further in making the generator inoperative and free from gas pressure before opening the residue drain of the carbide filling opening on top of the hopper4 ,some machines are made so that they automatically cease to generate should there be a sudden and abnormal withdrawal of gas such as would be caused by a bad leak4 ,this method of adding safety by automatic means and interlocking parts may be carried to any extent that seems desirable or necessary to the maker4 ,all generators should be provided with escape or relief pipes of large size which lead to the open air4 ,these pipes are carried so that condensation will drain back toward the generator and after being led out of the building to a point at least twelve feet above ground1 they end in a protecting hood so that no rain or solid matter can find its way into them4 ,any escape of gas which might ordinarily pass into the generator room is led into these escape pipes1 all parts of the system being connected with the pipe so that the gas will find this way out4 ,safety blow off valves are provided so that any excess gas which cannot be contained by the gas holder may be allowed to escape without causing an undue rise in pressure4 ,this valve also allows the escape of pressure above that for which the generator was designed4 ,gas released in this way passes into the escape pipe just described4 ,inasmuch as the pressure of the oxygen is much greater than that of the acetylene when used in the torch1 it will be seen that anything that caused the torch outlet to become closed would allow the oxygen to force the acetylene back into the generator and the oxygen would follow it1 making a very explosive mixture4 ,this return of the gas is prevented by a hydraulic safety valve or back pressure valve1 as it is often called4 ,mechanical check valves have been found unsuitable for this use and those which employ water as a seal are now required by the insurance rules4 ,the valve itself 7,figure #ac7 consists of a large cylinder containing water to a certain depth1 which is indicated on the valve body4 ,two pipes come into the upper end of this cylinder and lead down into the water1 one being longer than the other4 ,the shorter pipe leads to the escape pipe mentioned above1 while the longer one comes from the generator4 ,the upper end of the cylinder has an opening to which is attached the pipe leading to the torches4 ,illustration3 ,figure #ac4--;,hydraulic ,back-,pressure ,valve4 ,a1 ,acetylene supply line2 ,b1 ,vent pipe2 ,c1 ,water filling plug2 ,d1 ,acetylene service cock2 ,e1 ,plug to gauge height of water2 ,f1 ,gas openings under water2 ,g1 ,return pipe for sealing water2 ,h1 ,tube to carry gas below water line2 ,i1 ,tube to carry gas to escape pipe2 ,j1 ,gas chamber2 ,k1 ,plug in upper gas chamber2 ,l1 ,high water level2 ,m1 ,opening through which water returns2 ,o1 ,bottom clean out casting ,the gas coming from the generator through the longer pipe passes out of the lower end of the pipe which is under water and bubbles up through the water to the space in the top of the cylinder4 ,from there the gas goes to the pipe leading to the torches4 ,the shorter pipe is closed by the depth of water so that the gas does not escape to the relief pipe4 ,as long as the gas flows in the normal direction as described there will be no escape to the air4 ,should the gas in the torch line return into the hydraulic valve its pressure will lower the level of water in the cylinder by forcing some of the liquid up into the two pipes4 ,as the level of the water lowers1 the shorter pipe will be uncovered first1 and as this is the pipe leading to the open air the gas will be allowed to escape1 while the pipe leading back to the generator is still closed by the water seal4 ,as soon as this reverse flow ceases1 the water will again resume its level and the action will continue4 ,because of the small amount of water blown out of the escape pipe each time the valve is called upon to perform this duty1 it is necessary to see that the correct water level is always maintained4 ,while there are modifications of this construction1 the same principle is used in all types4 ,the pressure escape valve is often attached to this hydraulic valve body4 ,construction ,details4--,flexible tubing 7except at torches71 swing pipe joints1 springs1 mechanical check valves1 chains1 pulleys and lead or fusible piping should never be used on acetylene apparatus except where the failure of those parts will not affect the safety of the machine or permit1 either directly or indirectly1 the escape of gas into a room4 ,floats should not be used except where failure will only render the machine inoperative4 ,it should be said that the ,national ,board of ,fire ,underwriters have established an inspection service for acetylene generators and any apparatus which bears their label1 stating that that particular model and type has been passed1 is safe to use4 ,this service is for the best interests of all concerned and looks toward the prevention of accidents4 ,such inspection is a very important and desirable feature of any outfit and should be insisted upon4 ,location of ,generators4--,generators should preferably be placed outside of insured buildings and in properly constructed generator houses4 ,the operating mechanism should have ample room to work in and there should be room enough for the attendant to reach the various parts and perform the required duties without hindrance or the need of artificial light4 ,they should also be protected from tampering by unauthorized persons4 ,generator houses should not be within five feet of any opening into1 nor have any opening toward1 any adjacent building1 and should be kept under lock and key4 ,the size of the house should be no greater than called for by the requirements mentioned above and it should be well ventilated4 ,the foundation for the generator itself should be of brick1 stone1 concrete or iron1 if possible4 ,if of wood1 they should be extra heavy1 located in a dry place and open to circulation of air4 ,a board platform is not satisfactory1 but the foundation should be of heavy planking or timber to make a firm base and so that the air can circulate around the wood4 ,the generator should stand level and no strain should be placed on any of the pipes or connections or any parts of the generator proper4 ,,chapter ,,iv ,,welding ,,instruments ,,valves ,tank ,valves4--,the acetylene tank valve is of the needle type1 fitted with suitable stuffing box nuts and ending in an exposed square shank to which the special wrench may be fitted when the valve is to be opened or closed4 ,the valve used on ,linde oxygen cylinders is also a needle type1 but of slightly more complex construction4 ,the body of the valve1 which screws into the top of the cylinder1 has an opening below through which the gas comes from the cylinder1 and another opening on the side through which it issues to the torch line4 ,a needle screws down from above to close this lower opening4 ,the needle which closes the valve is not connected directly to the threaded member1 but fits loosely into it4 ,the threaded part is turned by a small hand wheel attached to the upper end4 ,when this hand wheel is turned to the left1 or up1 as far as it will go1 opening the valve1 a rubber disc is compressed inside of the valve body and this disc serves to prevent leakage of the gas around the spindle4 ,the oxygen valve also includes a safety nut having a small hole through it closed by a fusible metal which melts at #bej ,fahrenheit4 ,melting of this plug allows the gas to exert its pressure against a thin copper diaphragm1 this diaphragm bursting under the gas pressure and allowing the oxygen to escape into the air4 ,the hand wheel and upper end of the valve mechanism are protected during shipment by a large steel cap which covers them when screwed on to the end of the cylinder4 ,this cap should always be in place when tanks are received from the makers or returned to them4 ,illustration3 ,figure #ad4--,regulating ,valve ,regulating ,valves4--,while the pressure in the gas containers may be anything from zero to #a1hjj pounds1 and will vary as the gas is withdrawn1 the pressure of the gas admitted to the torch must be held steady and at a definite point4 ,this is accomplished by various forms of automatic regulating valves1 which1 while they differ somewhat in details of construction1 all operate on the same principle4 ,the regulator body 7,figure #ad7 carries a union which attaches to the side outlet on the oxygen tank valve4 ,the gas passes through this union1 following an opening which leads to a large gauge which registers the pressure on the oxygen remaining in the tank and also to a very small opening in the end of a tube4 ,the gas passes through this opening and into the interior of the regulator body4 ,inside of the body is a metal or rubber diaphragm placed so that the pressure of the incoming gas causes it to bulge slightly4 ,attached to the diaphragm is a sleeve or an arm tipped with a small piece of fibre1 the fibre being placed so that it is directly opposite the small hole through which the gas entered the diaphragm chamber4 ,the slight movement of the diaphragm draws the fibre tightly over the small opening through which the gas is entering1 with the result that further flow is prevented4 ,against the opposite side of the diaphragm is the end of a plunger4 ,this plunger is pressed against the diaphragm by a coiled spring4 ,the tension on the coiled spring is controlled by the operator through a threaded spindle ending in a wing or milled nut on the outside of the regulator body4 ,screwing in on the nut causes the tension on the spring to increase1 with a consequent increase of pressure on the side of the diaphragm opposite to that on which the gas acts4 ,inasmuch as the gas pressure acted to close the small gas opening and the spring pressure acts in the opposite direction from the gas1 it will be seen that the spring pressure tends to keep the valve open4 ,when the nut is turned way out there is of course1 no pressure on the spring side of the diaphragm and the first gas coming through automatically closes the opening through which it entered4 ,if now the tension on the spring be slightly increased1 the valve will again open and admit gas until the pressure of gas within the regulator is just sufficient to overcome the spring pressure and again close the opening4 ,there will then be a pressure of gas within the regulator that corresponds to the pressure placed on the spring by the operator4 ,an opening leads from the regulator interior to the torch lines so that all gas going to the torches is drawn from the diaphragm chamber4 ,any withdrawal of gas will1 of course1 lower the pressure of that remaining inside the regulator4 ,the spring tension1 remaining at the point determined by the operator1 will overcome this lessened pressure of the gas1 and the valve will again open and admit enough more gas to bring the pressure back to the starting point4 ,this action continues as long as the spring tension remains at this point and as long as any gas is taken from the regulator4 ,increasing the spring tension will require a greater gas pressure to close the valve and the pressure of that in the regulator will be correspondingly higher4 ,when the regulator is not being used1 the hand nut should be unscrewed until no tension remains on the spring1 thus closing the valve4 ,after the oxygen tank valve is open1 the regulator hand nut is slowly screwed in until the spring tension is sufficient to give the required pressure in the torch lines4 ,another gauge is attached to the regulator so that it communicates with the interior of the diaphragm chamber1 this gauge showing the gas pressure going to the torch4 ,it is customary to incorporate a safety valve in the regulator which will blow off at a dangerous pressure4 ,in regulating valves and tank valves1 as well as all other parts with which the oxygen comes in contact1 it is not permissible to use any form of oil or grease because of danger of ignition and explosion4 ,the mechanism of a regulator is too delicate to be handled in the ordinary shop and should any trouble or leakage develop in this part of the equipment it should be sent to a company familiar with this class of work for the necessary repairs4 ,gas must never be admitted to a regulator until the hand nut is all the way out1 because of danger to the regulator itself and to the operator as well4 ,a regulator can only be properly adjusted when the tank valve and torch valves are fully opened4 ,illustration3 ,figure #ae4--;,high and ,low ,pressure ,gauges with ,regulator ,acetylene regulators are used in connection with tanks of compressed gas4 ,they are built on exactly the same lines as the oxygen regulating valve and operate in a similar way4 ,one gauge only1 the low pressure indicator1 is used for acetylene regulators1 although both high and low pressure may be used if desired4 7,see ,figure #ae47 ,,torches ,flame is always produced by the combustion of a gas with oxygen and in no other way4 ,when we burn oil or candles or anything else1 the material of the fuel is first turned to a gas by the heat and is then burned by combining with the oxygen of the air4 ,if more than a normal supply of air is forced into the flame1 a greater heat and more active burning follows4 ,if the amount of air1 and consequently oxygen1 is reduced1 the flame becomes smaller and weaker and the combustion is less rapid4 ,a flame may be easily extinguished by shutting off all of its air supply4 ,the oxygen of the combustion only forms one-fifth of the total volume of air2 therefore1 if we were to supply pure oxygen in place of air1 and in equal volume1 the action would be several times as intense4 ,if the oxygen is mixed with the fuel gas in the proportion that burns to the very best advantage1 the flame is still further strengthened and still more heat is developed because of the perfect combustion4 ,the greater the amount of fuel gas that can be burned in a certain space and within a certain time1 the more heat will be developed from that fuel4 ,the great amount of heat contained in acetylene gas1 greater than that found in any other gaseous fuel1 is used by leading this gas to the oxy-acetylene torch and there combining it with just the right amount of oxygen to make a flame of the greatest power and heat than can possibly be produced by any form of combustion of fuels of this kind4 ,the heat developed by the flame is about #fcjj ,fahrenheit and easily melts all the metals1 as well as other solids4 ,other gases have been and are now being used in the torch4 ,none of them1 however1 produce the heat that acetylene does1 and therefore the oxy-acetylene process has proved the most useful of all4 ,hydrogen was used for many years before acetylene was introduced in this field4 ,the oxy-hydrogen flame develops a heat far below that of oxy-acetylene1 namely #dejj ,fahrenheit4 ,coal gas1 benzine gas1 blaugas and others have also been used in successful applications1 but for the present we will deal exclusively with the acetylene fuel4 ,it was only with great difficulty that the obstacles in the way of successfully using acetylene were overcome by the development of practicable controlling devices and torches1 as well as generators4 ,at present the oxy-acetylene process is the most universally adaptable1 and probably finds the most widely extended field of usefulness of any welding process4 ,the theoretical proportion of the gases for perfect combustion is two and one-half volumes of oxygen to one of acetylene4 ,in practice this proportion is one and one-eighth or one and one-quarter volumes of oxygen to one volume of acetylene1 so that the cost is considerably reduced below what it would be if the theoretical quantity were really necessary1 as oxygen costs much more than acetylene in all cases4 ,while the heat is so intense as to fuse anything brought into the path of the flame1 it is localized in the small welding cone at the torch tip so that the torch is not at all difficult to handle without special protection except for the eyes1 as already noted4 ,the art of successful welding may be acquired by any operator of average intelligence within a reasonable time and with some practice4 ,one trouble met with in the adoption of this process has been that the operation looks so simple and so easy of performance that unskilled and unprepared persons have been tempted to try welding1 with results that often caused condemnation of the process1 when the real fault lay entirely with the operator4 ,the form of torch usually employed is from twelve to twenty-four inches long and is composed of a handle at one end with tubes leading from this handle to the welding head or torch proper4 ,at or near one end of the handle are adjustable cocks or valves for allowing the gases to flow into the torch or to prevent them from doing so4 ,these cocks are often used for regulating the pressure and amount of gas flowing to the welding head1 but are not always constructed for this purpose and should not be so used when it is possible to secure pressure adjustment at the regulators 7,figure #af74 ,figure #af shows three different sizes of torches4 ,the number #e torch is designed especially for jewelers' work and thin sheet steel welding4 ,it is eleven inches in length and weighs nineteen ounces4 ,the tips for the number #aj torch are interchangeable with the number #e4 ,the number #aj torch is adapted for general use on light and medium heavy work4 ,it has six tips and its length is sixteen inches1 with a weight of twenty-three ounces4 ,the number #ae torch is designed for heavy work1 being twenty-five inches in length1 permitting the operator to stand away from the heat of the metal being worked4 ,these heavy tips are in two parts1 the oxygen check being renewable4 ,illustration3 ,figure #af4--,three ,sizes of ,torches1 with ,tips ,figures #ag and #ah show two sizes of another welding torch4 ,still another type is shown in ,figure #ai with four interchangeable tips1 the function of each being as follows3 ,no4 #a4 ,for heavy castings4 ,no4 #b4 ,light castings and heavy sheet metal4 ,no4 #c4 ,light sheet metal4 ,no4 #d4 ,very light sheet metal and wire4 ,illustration3 ,figure #ag4--;,cox ,welding ,torch 7,no4 #a7 ,illustration3 ,figure #ah4--;,cox ,welding ,torch 7,no4 #b7 ,illustration3 ,figure #ai4--,monarch ,welding ,torch ,at the side of the shut off cock away from the torch handle the gas tubes end in standard forms of hose nozzles1 to which the rubber hose from the gas supply tanks or generators can be attached4 ,the tubes from the handle to the head may be entirely separate from each other1 or one may be contained within the other4 ,as a general rule the upper one of two separate tubes carries the oxygen1 while this gas is carried in the inside tube when they are concentric with each other4 ,in the welding head is the mixing chamber designed to produce an intimate mixture of the two gases before they issue from the nozzle to the flame4 ,the nozzle1 or welding tip1 of a suitable size are design for the work to be handled and the pressure of gases being used1 is attached to the welding head and consists essentially of the passage at the outer end of which the flame appears4 ,the torch body and tubes are usually made of brass1 although copper is sometimes used4 ,the joint must be very strong1 and are usually threaded and soldered with silver solder4 ,the nozzle proper is made from copper1 because it withstands the heat of the flame better than other less suitable metals4 ,the torch must be built in such a way that it is not at all liable to come apart under the influence of high temperatures4 ,all torches are constructed in such a way that it is impossible for the gases to mix by any possible chance before they reach the head1 and the amount of gas contained in the head and tip after being mixed is made as small as possible4 ,in order to prevent the return of the flame through the acetylene tube under the influence of the high pressure oxygen some form of back flash preventer is usually incorporated in the torch at or near the point at which the acetylene enters4 ,this preventer takes the form of some porous and heat absorbing material1 such as aluminum shavings1 contained in a small cavity through which the gas passes on its way to the head4 ,high ,pressure ,torches4--,torches are divided into the same classes as are the generators2 that is1 high pressure1 medium pressure and low pressure4 ,as mentioned before1 the medium pressure is usually called the high pressure1 because there are very few true high pressure systems in use1 and comparatively speaking the medium pressure type is one of high pressure4 ,illustration3 ,figure #bj4--;,high ,pressure ,torch ,head ,with a true high pressure torch 7,figure #bj7 the gases are used at very nearly equal heads so that the mixing before ignition is a simple matter4 ,this type admits the oxygen at the inner end of a straight passage leading to the tip of the nozzle4 ,the acetylene comes into this same passage from openings at one side and near the inner end4 ,the difference in direction of the two gases as they enter the passage assists in making a homogeneous mixture4 ,the construction of this nozzle is perfectly simple and is easily understood4 ,the true high pressure torch nozzle is only suited for use with compressed and dissolved acetylene1 no other gas being at a sufficient pressure to make the action necessary in mixing the gases4 ,medium ,pressure ,torches4--,the medium pressure 7usually called high pressure7 torch 7,figure #ba7 uses acetylene from a medium pressure generator or from tanks of compressed gas1 but will not take the acetylene from low pressure generators4 ,illustration3 ,figure #ba4--,medium ,pressure ,torch ,head ,the construction of the mixing chamber and nozzle is very similar to that of the high pressure torch1 the gases entering in the same way and from the same positions of openings4 ,the pressure of the acetylene is but little lower than that of the oxygen1 and the two gases1 meeting at right angles1 form a very intimate mixture at this point of juncture4 ,the mixture in its proportions of gases depends entirely on the sizes of the oxygen and acetylene openings into the mixing chamber and on the pressures at which the gases are admitted4 ,there is a very slight injector action as the fast moving stream of oxygen tends to draw the acetylene from the side openings into the chamber1 but the operation of the torch does not depend on this action to any extent4 ,low ,pressure ,torches4--,the low pressure torch 7,figure #bb7 will use gas from low pressure generators from medium pressure machines or from tanks in which it has been compressed and dissolved4 ,this type depends for a perfect mixture of gas upon the principle of the injector just as it is applied in steam boiler practice4 ,illustration3 ,figure #bb4--,low ,pressure ,torch with ,separate ,injector ,nozzle ,the oxygen enters the head at considerable pressure and passes through its tube to a small jet within the head4 ,the opening of this jet is directly opposite the end of the opening through the nozzle which forms the mixing chamber and the path of the gases to the flame4 ,a small distance remains between the opening from which the oxygen issues and the inner opening into the mixing passage4 ,the stream of oxygen rushes across this space and enters the mixing chamber1 being driven by its own pressure4 ,the acetylene enters the head in an annular space surrounding the oxygen tube4 ,the space between oxygen jet and mixing chamber opening is at one end of this acetylene space and the stream of oxygen seizes the acetylene and under the injector action draws it into the mixing chamber1 it being necessary only to have a sufficient supply of acetylene flowing into the head to allow the oxygen to draw the required proportion for a proper mixture4 ,the volume of gas drawn into the mixing chamber depends on the size of the injector openings and the pressure of the oxygen4 ,in practice the oxygen pressure is not altered to produce different sized flames1 but a new nozzle is substituted which is designed to give the required flame4 ,each nozzle carries its own injector1 so that the design is always suited to the conditions4 ,while torches are made having the injector as a permanent part of the torch body1 the replaceable nozzle is more commonly used because it makes the one torch suitable for a large range of work and a large number of different sized flames4 ,with the replaceable head a definite pressure of oxygen is required for the size being used1 this pressure being the one for which the injector and corresponding mixing chamber were designed in producing the correct mixture4 ,adjustable ,injectors4-,another form of low pressure torch operates on the injector principle1 but the injector itself is a permanent part of the torch1 the nozzle only being changed for different sizes of work and flame4 ,the injector is placed in or near the handle and its opening is the largest required by any work that can be handled by this particular torch4 ,the opening through the tip of the injector through which the oxygen issues on its way to the mixing chamber may be wholly or partly closed by a needle valve which may be screwed into the opening or withdrawn from it1 according to the operator's judgment4 ,the needle valve ends in a milled nut outside the torch handle1 this being the adjustment provided for the different nozzles4 ,torch ,construction4--,a well designed torch is so designed that the weight distribution is best for holding it in the proper position for welding4 ,when a torch is grasped by its handle with the gas hose attached1 it should balance so that it does not feel appreciably heavier on one end than on the other4 ,the head and nozzle may be placed so that the flame issues in a line at right angles with the torch body1 or they may be attached at an angle convenient for the work to be done4 ,the head set at an angle of from #abj to #agj degrees with the body is usually preferred for general work in welding1 while the cutting torch usually has its head at right angles to the body4 ,removable nozzles have various size openings through them and the different sizes are designated by numbers from #a up4 ,the same number does not always indicate the same size opening in torches of different makes1 nor does it indicate a nozzle of the same capacity4 ,the design of the nozzle1 the mixing chamber1 the injector1 when one is used1 and the size of the gas openings must be such that all these things are suited to each other if a proper mixture of gas is to be secured4 ,parts that are not made to work together are unsafe if used because of the danger of a flash back of the flame into the mixing chamber and gas tubes4 ,it is well known that flame travels through any inflammable gas at a certain definite rate of speed1 depending on the degree of inflammability of the gas4 ,the easier and quicker the gas burns1 the faster will the flame travel through it4 ,if the gas in the nozzle and mixing chamber stood still1 the flame would immediately travel back into these parts and produce an explosion of more or less violence4 ,the speed with which the gases issue from the nozzle prevent this from happening because the flame travels back through the gas at the same speed at which the gas issues from the torch tip4 ,should the velocity of the gas be greater than the speed of flame propagation through it1 it will be impossible to keep the flame at the tip1 the tendency being for a space of unburned gas to appear between tip and flame4 ,on the other hand1 should the speed of the flame exceed the velocity with which the gas comes from the torch there will result a flash back and explosion4 ,care of ,torches4--,an oxy-acetylene torch is a very delicate and sensitive device1 much more so that appears on the surface4 ,it must be given equally as good care and attention as any other high-priced piece of machinery if it is to be maintained in good condition for use4 ,it requires cleaning of the nozzles at regular intervals if used regularly4 ,this cleaning is accomplished with a piece of copper or brass wire run through the opening1 and never with any metal such as steel or iron that is harder than the nozzle itself1 because of the danger of changing the size of the openings4 ,the torch head and nozzle can often be cleaned by allowing the oxygen to blow through at high pressure without the use of any tools4 ,in using a torch a deposit of carbon will gradually form inside of the head1 and this deposit will be more rapid if the operator lights the stream of acetylene before turning any oxygen into the torch4 ,this deposit may be removed by running kerosene through the nozzle while it is removed from the torch1 setting fire to the kerosene and allowing oxygen to flow through while the oil is burning4 ,should a torch become clogged in the head or tubes1 it may usually be cleaned by removing the oxygen hose from the handle end1 closing the acetylene cock on the torch1 placing the end of the oxygen hose over the opening in the nozzle and turning on the oxygen under pressure to blow the obstruction back through the passage that it has entered4 ,by opening the acetylene cock and closing the oxygen cock at the handle1 the acetylene passages may then be cleaned in the same way4 ,under no conditions should a torch be taken apart any more than to remove the changeable nozzle1 except in the hands of those experienced in this work4 ,nozzle ,sizes4--,the size of opening through the nozzle is determined according to the thickness and kind of metal being handled4 ,the following sizes are recommended for steel3 ,davis-,bournonville4 ,oxweld ,low ,thickness of ,metal 7,medium ,pressure47 ,pressure #a_/cb ,tip ,no4 #a ,head ,no4 #b #a_/af #b #e_/fd #c #c_/cb #c #d #c_/h #d #e #c_/af #e #f #a_/d #f #g #e_/af #g #c_/h #h #h #a_/b #i #aj #e_/h #aj #ab #c_/d #aa #ae ,very heavy #ab #ae ,cutting ,torches4--,steel may be cut with a jet of oxygen at a rate of speed greater than in any other practicable way under usual conditions4 ,the action consists of burning away a thin section of the metal by allowing a stream of oxygen to flow onto it while the gas is at high pressure and the metal at a white heat4 ,illustration3 ,figure #bc4--;,cutting ,torch ,the cutting torch 7,figure #bc7 has the same characteristics as the welding torch1 but has an additional nozzle or means for temporarily using the welding opening for the high pressure oxygen4 ,the oxygen issues from the opening while cutting at a pressure of from ten to #ajj pounds to the square inch4 ,the work is first heated to a white heat by adjusting the torch for a welding flame4 ,as soon as the metal reaches this temperature1 the high pressure oxygen is turned on to the white-hot portion of the steel4 ,when the jet of gas strikes the metal it cuts straight through1 leaving a very narrow slot and removing but little metal4 ,thicknesses of steel up to ten inches can be economically handled in this way4 ,the oxygen nozzle is usually arranged so that it is surrounded by a number of small jets for the heating flame4 ,it will be seen that this arrangement makes the heating flame always precede the oxygen jet1 no matter in which direction the torch is moved4 ,the torch is held firmly1 either by hand or with the help of special mechanism for guiding it in the desired path1 and is steadily advanced in the direction it is desired to extend the cut1 the rate of advance being from three inches to two feet per minute through metal from nine inches down to one-quarter of an inch in thickness4 ,the following data on cutting is given by the ,davis-,bournonville ,company3 ,cubic ,feet ,cost of ,thickness of ,gas ,inches ,gases of ,cutting ,heating per ,foot ,oxygen ,cut per per ,foot ,steel ,oxygen ,oxygen of ,cut ,acetylene ,min4 of ,cut #a_/d #aj lbs4 #d lbs4 4#dj 4#jhf #bd 4#jac #a_/b #bj #d 4#ia 4#aej #ae 4#jbi #c_/d #cj #d #a4af 4#aej #ae 4#jcf #a #cj #d #a4de 4#agb #ab 4#jde #a #a_/b #cj #e #b4dj 4#chj #ab 4#jgf #b #dj #e #b4if 4#chj #ab 4#jic #d #ej #e #i4gj 4#hjj #g 4#bii #f #gj #f #ba4ji #a4ej #d 4#fdh #i #ajj #f #dc4bj #b4jj #c #a4caa ,acetylene-,air ,torch4--,a form of torch which burns the acetylene after mixing it with atmospheric air at normal pressure rather than with the oxygen under higher pressures has been found useful in certain pre-heating1 brazing and similar operations4 ,this torch 7,figure #bd7 is attached by a rubber gas hose to any compressed acetylene tank and is regulated as to flame size and temperature by opening or closing the tank valve more or less4 ,after attaching the torch to the tank1 the gas is turned on very slowly and is lighted at the torch tip4 ,the adjustment should cause the presence of a greenish-white cone of flame surrounded by a larger body of burning gas1 the cone starting at the mouth of the torch4 ,illustration3 ,figure #bd4--;,acetylene-,air ,torch ,by opening the tank valve more1 a longer and hotter flame is produced1 the length being regulated by the tank valve also4 ,this torch will give sufficient heat to melt steel1 although not under conditions suited to welding4 ,because of the excess of acetylene always present there is no danger of oxidizing the metal being heated4 ,the only care required by this torch is to keep the small air passages at the nozzle clean and free from carbon deposits4 ,the flame should be extinguished when not in use rather than turned low1 because this low flame rapidly deposits large quantities of soot in the burner4 ,,chapter ,v ,,oxy-,,acetylene ,,welding ,,practice ,,preparation ,,of ,,work ,preheating4--,the practice of heating the metal around the weld before applying the torch flame is a desirable one for two reasons4 ,first1 it makes the whole process more economical2 second1 it avoids the danger of breakage through expansion and contraction of the work as it is heated and as it cools4 ,when it is desired to join two surfaces by welding them1 it is1 of course1 necessary to raise the metal from the temperature of the surrounding air to its melting point1 involving an increase in temperature of from one thousand to nearly three thousand degrees4 ,to obtain this entire increase of temperature with the torch flame is very wasteful of fuel and of the operator's time4 ,the total amount of heat necessary to put into metal is increased by the conductivity of that metal because the heat applied at the weld is carried to other parts of the piece being handled until the whole mass is considerably raised in temperature4 ,to secure this widely distributed increase the various methods of preheating are adopted4 ,as to the second reason for preliminary heating4 ,it is understood that the metal added to the joint is molten at the time it flows into place4 ,all the metals used in welding contract as they cool and occupy a much smaller space than when molten4 ,if additional metal is run between two adjoining surfaces which are parts of a surrounding body of cool metal1 this added metal will cool while the surfaces themselves are held stationary in the position they originally occupied4 ,the inevitable result is that the metal added will crack under the strain1 or1 if the weld is exceptionally strong1 the main body of the work will be broken by the force of contraction4 ,to overcome these difficulties is the second and most important reason for preheating and also for slow cooling following the completion of the weld4 ,there are many ways of securing this preheating4 ,the work may be brought to a red heat in the forge if it is cast iron or steel2 it may be heated in special ovens built for the purpose2 it may be placed in a bed of charcoal while suitably supported2 it may be heated by gas or gasoline preheating torches1 and with very small work the outer flame of the welding torch automatically provides means to this end4 ,the temperature of the parts heated should be gradually raised in all cases1 giving the entire mass of metal a chance to expand equally and to adjust itself to the strains imposed by the preheating4 ,after the region around the weld has been brought to a proper temperature the opening to be filled is exposed so that the torch flame can reach it1 while the remaining surfaces are still protected from cold air currents and from cooling through natural radiation4 ,one of the commonest methods and one of the best for handling work of rather large size is to place the piece to be welded on a bed of fire brick and build a loose wall around it with other fire brick placed in rows1 one on top of the other1 with air spaces left between adjacent bricks in each row4 ,the space between the brick retaining wall and the work is filled with charcoal1 which is lighted from below4 ,the top opening of the temporary oven is then covered with asbestos and the fire kept up until the work has been uniformly raised in temperature to the desired point4 ,when much work of the same general character and size is to be handled1 a permanent oven may be constructed of fire brick1 leaving a large opening through the top and also through one side4 ,charcoal may be used in this form of oven as with the temporary arrangement1 or the heat may be secured from any form of burner or torch giving a large volume of flame4 ,in any method employing flame to do the heating1 the work itself must be protected from the direct blast of the fire4 ,baffles of brick or metal should be placed between the mouth of the torch and the nearest surface of the work so that the flame will be deflected to either side and around the piece being heated4 ,the heat should be applied to bring the point of welding to the highest temperature desired and1 except in the smallest work1 the heat should gradually shade off from this point to the other parts of the piece4 ,in the case of cast iron and steel the temperature at the point to be welded should be great enough to produce a dull red heat4 ,this will make the whole operation much easier1 because there will be no surrounding cool metal to reduce the temperature of the molten material from the welding rod below the point at which it will join the work4 ,from this red heat the mass of metal should grow cooler as the distance from the weld becomes greater1 so that no great strain is placed upon any one part4 ,with work of a very irregular shape it is always best to heat the entire piece so that the strains will be so evenly distributed that they can cause no distortion or breakage under any conditions4 ,the melting point of the work which is being preheated should be kept in mind and care exercised not to approach it too closely4 ,special care is necessary with aluminum in this respect1 because of its low melting temperature and the sudden weakening and flowing without warning4 ,workmen have carelessly overheated aluminum castings and1 upon uncovering the piece to make the weld1 have been astonished to find that it had disappeared4 ,six hundred degrees is about the safe limit for this metal4 ,it is possible to gauge the exact temperature of the work with a pyrometer1 but when this instrument cannot be procured1 it might be well to secure a number of temperature cones from a chemical or laboratory supply house4 ,these cones are made from material that will soften at a certain heat and in form they are long and pointed4 ,placed in position on the part being heated1 the point may be watched1 and when it bends over it is sure that the metal itself has reached a temperature considerably in excess of the temperature at which that particular cone was designed to soften4 ,the object in preheating the metal around the weld is to cause it to expand sufficiently to open the crack a distance equal to the contraction when cooling from the melting point4 ,in the case of a crack running from the edge of a piece into the body or of a crack wholly within the body1 it is usually satisfactory to heat the metal at each end of the opening4 ,this will cause the whole length of the crack to open sufficiently to receive the molten material from the rod4 ,the judgment of the operator will be called upon to decide just where a piece of metal should be heated to open the weld properly4 ,it is often possible to apply the preheating flame to a point some distance from the point of work if the parts are so connected that the expansion of the heated part will serve to draw the edges of the weld apart4 ,whatever part of the work is heated to cause expansion and separation1 this part must remain hot during the entire time of welding and must then cool slowly at the same time as the metal in the weld cools4 ,illustration3 ,figure #be4--,preheating at ,a ,while ,welding at ,b4 ,c also ,may ,be ,heated4 ,an example of heating points away from the crack might be found in welding a lattice work with one of the bars cracked through 7,figure #be74 ,if the strips parallel and near to the broken bar are heated gradually1 the work will be so expanded that the edges of the break are drawn apart and the weld can be successfully made4 ,in this case1 the parallel bars next to the broken one would be heated highest1 the next row not quite so hot and so on for some distance away4 ,if only the one row were heated1 the strains set up in the next ones would be sufficient to cause a new break to appear4 ,illustration3 ,figure #bf4--;,cutting ,through the ,rim of a ,wheel 7,cut ,shown at ,a7 ,if welding is to be done near the central portion of a large piece1 the strains will be brought to bear on the parts farthest away from the center4 ,should a fly wheel spoke be broken and made ready to weld1 the greatest strain will come on the rim of the wheel4 ,in cases like this it is often desirable to cut through at the point of greatest strain with a saw or cutting torch1 allowing free movement while the weld is made at the original break 7,figure #bf74 ,after the inside weld is completed1 the cut may be welded without danger1 for the reason that it will always be at some point at which severe strains cannot be set up by the contraction of the cooling metal4 ,illustration3 ,figure #bg4--,using a ,wedge ,while ,welding ,in materials that will spring to some extent without breakage1 that is1 in parts that are not brittle1 it may be possible to force the work out of shape with jacks or wedges 7,figure #bg7 in the same way that it would be distorted by heating and expanding some portion of it as described4 ,a careful examination will show whether this method can be followed in such a way as to force the edges of the break to separate4 ,if the plan seems feasible1 the wedges may be put in place and allowed to remain while the weld is completed4 ,as soon as the work is finished the wedges should be removed so that the natural contraction can take place without damage4 ,it should always be remembered that it is not so much the expansion of the work when heated as it is the contraction caused by cooling that will do the damage4 ,a weld may be made that1 to all appearances1 is perfect and it may be perfect when completed2 but if provision has not been made to allow for the contraction that is certain to follow1 there will be a breakage at some point4 ,it is not possible to weld the simplest shapes1 other than straight bars1 without considering this difficulty and making provision to take care of it4 ,the exact method to employ in preheating will always call for good judgment on the part of the workman1 and he should remember that the success or failure of his work will depend fully as much on proper preparation as on correct handling of the weld itself4 ,it should be remembered that the outer flame of the oxy-acetylene torch may be depended on for a certain amount of preheating1 as this flame gives a very large volume of heat1 but a heat that is not so intense nor so localized as the welding flame itself4 ,the heat of this part of the flame should be fully utilized during the operation of melting the metal and it should be so directed1 when possible1 that it will bring the parts next to be joined to as high a temperature as possible4 ,when the work has been brought to the desired temperature1 all parts except the break and the surface immediately surrounding it on both sides should be covered with heavy sheet asbestos4 ,this protecting cover should remain in place throughout the operation and should only be moved a distance sufficient to allow the torch flame to travel in the path of the weld4 ,the use of asbestos in this way serves a twofold purpose4 ,it retains the heat in the work and prevents the breakage that would follow if a draught of air were to strike the heated metal1 and it also prevents such a radiation of heat through the surrounding air as would make it almost impossible for the operator to perform his work1 especially in the case of large and heavy castings when the amount of heat utilized is large4 ,cleaning and ,champfering4--,a perfect weld can never be made unless the surfaces to be joined have been properly prepared to receive the new metal4 ,all spoiled1 burned1 corroded and rough particles must positively be removed with chisel and hammer and with a free application of emery cloth and wire brush4 ,the metal exposed to the welding flame should be perfectly clean and bright all over1 or else the additional material will not unite1 but will only stick at best4 ,illustration3 ,figure #bh4--,tapering the ,opening ,formed by a ,break ,following the cleaning it is always necessary to bevel1 or champfer1 the edges except in the thinnest sheet metal4 ,to make a weld that will hold1 the metal must be made into one piece1 without holes or unfilled portions at any point1 and must be solid from inside to outside4 ,this can only be accomplished by starting the addition of metal at one point and gradually building it up until the outside1 or top1 is reached4 ,with comparatively thin plates the molten metal may be started from the side farthest from the operator and brought through1 but with thicker sections the addition is started in the middle and brought flush with one side and then with the other4 ,it will readily be seen that the molten material cannot be depended upon to flow between the tightly closed surfaces of a crack in a way that can be at all sure to make a true weld4 ,it will be necessary for the operator to reach to the farthest side with the flame and welding rod1 and to start the new surfaces there4 ,to allow this1 the edges that are to be joined are beveled from one side to the other 7,figure #bh71 so that when placed together in approximately the position they are to occupy they will leave a grooved channel between them with its sides at an angle with each other sufficient in size to allow access to every point of each surface4 ,illustration3 ,figure #bi4--;,beveling for ,thin ,work ,illustration3 ,figure #cj4--;,beveling for ,thick ,work ,with work less than one-fourth inch thick1 this angle should be forty-five degrees on each piece 7,figure #bi71 so that when they are placed together the extreme edges will meet at the bottom of a groove whose sides are square1 or at right angles1 to each other4 ,this beveling should be done so that only a thin edge is left where the two parts come together1 just enough points in contact to make the alignment easy to hold4 ,with work of a thickness greater than a quarter of an inch1 the angle of bevel on each piece may be sixty degrees 7,figure #cj71 so that when placed together the angle included between the sloping sides will also be sixty degrees4 ,if the plate is less than one-eighth of an inch thick the beveling is not necessary1 as the edges may be melted all the way through without danger of leaving blowholes at any point4 ,illustration3 ,figure #ca4--;,beveling ,both ,sides of a ,thick ,piece ,illustration3 ,figure #cb4--;,beveling the ,end of a ,pipe ,this beveling may be done in any convenient way4 ,a chisel is usually most satisfactory and also quickest4 ,small sections may be handled by filing1 while metal that is too hard to cut in either of these ways may be shaped on the emery wheel4 ,it is not necessary that the edges be perfectly finished and absolutely smooth1 but they should be of regular outline and should always taper off to a thin edge so that when the flame is first applied it can be seen issuing from the far side of the crack4 ,if the work is quite thick and is of a shape that will allow it to be turned over1 the bevel may be brought from both sides 7,figure #ca71 so that there will be two grooves1 one on each surface of the work4 ,after completing the weld on one side1 the piece is reversed and finished on the other side4 ,figure #cb shows the proper beveling for welding pipe4 ,figure #cc shows how sheet metal may be flanged for welding4 ,welding should not be attempted with the edges separated in place of beveled1 because it will be found impossible to build up a solid web of new metal from one side clear through to the other by this method4 ,the flame cannot reach the surfaces to make them molten while receiving new material from the rod1 and if the flame does not reach them it will only serve to cause a few drops of the metal to join and will surely cause a weak and defective weld4 ,illustration3 ,figure #cc4--;,flanging ,sheet ,metal for ,welding ,supporting ,work4--,during the operation of welding it is necessary that the work be well supported in the position it should occupy4 ,this may be done with fire brick placed under the pieces in the correct position1 or1 better still1 with some form of clamp4 ,the edges of the crack should touch each other at the point where welding is to start and from there should gradually separate at the rate of about one-fourth inch to the foot4 ,this is done so that the cooling of the molten metal as it is added will draw the edges together by its contraction4 ,care must be used to see that the work is supported so that it will maintain the same relative position between the parts as must be present when the work is finished4 ,in this connection it must be remembered that the expansion of the metal when heated may be great enough to cause serious distortion and to provide against this is one of the difficulties to be overcome4 ,perfect alignment should be secured between the separate parts that are to be joined and the two edges must be held up so that they will be in the same plane while welding is carried out4 ,if1 by any chance1 one drops below the other while molten metal is being added1 the whole job may have to be undone and done over again4 ,one precaution that is necessary is that of making sure that the clamping or supporting does not in itself pull the work out of shape while melted4 ,,torch ,,practice ,illustration3 ,figure #cd4--,rotary ,movement of ,torch in ,welding ,the weld is made by bringing the tip of the welding flame to the edges of the metals to be joined4 ,the torch should be held in the right hand and moved slowly along the crack with a rotating motion1 traveling in small circles 7,figure #cd71 so that the ,welding flame touches first on one side of the crack and then on the other4 ,on large work the motion may be simply back and forth across the crack1 advancing regularly as the metal unites4 ,it is usually best to weld toward the operator rather than from him1 although this rule is governed by circumstances4 ,the head of the torch should be inclined at an angle of about #fj degrees to the surface of the work4 ,the torch handle should extend in the same line with the break 7,figure #ce7 and not across it1 except when welding very light plates4 ,illustration3 ,figure #ce4--,torch ,held in ,line with the ,break ,if the metal is #a_/af inch or less in thickness it is only necessary to circle along the crack1 the metal itself furnishing enough material to complete the weld without additions4 ,heat both sides evenly until they flow together4 ,material thicker than the above requires the addition of more metal of the same or different kind from the welding rod1 this rod being held by the left hand4 ,the proper size rod for cast iron is one having a diameter equal to the thickness of metal being welded up to a one-half inch rod1 which is the largest used4 ,for steel the rod should be one-half the thickness of the metal being joined up to one-fourth inch rod4 ,as a general rule1 better results will be obtained by the use of smaller rods1 the very small sizes being twisted together to furnish enough material while retaining the free melting qualities4 ,illustration3 ,figure #cf4--,the ,welding ,rod ,should ,be ,held in the ,molten ,metal ,the tip of the rod must at all times be held in contact with the pieces being welded and the flame must be so directed that the two sides of the crack and the end of the rod are melted at the same time 7,figure #cf74 ,before anything is added from the rod1 the sides of the crack are melted down sufficiently to fill the bottom of the groove and join the two sides4 ,afterward1 as metal comes from the rod in filling the crack1 the flame is circled along the joint being made1 the rod always following the flame4 ,illustration3 ,figure #cg4--,welding ,pieces of ,unequal ,thickness ,figure #cg illustrates the welding of pieces of unequal thickness4 ,figure #ch illustrates welding at an angle4 ,the molten metal may be directed as to where it should go by the tip of the welding flame1 which has considerable force1 but care must be taken not to blow melted metal on to cooler surfaces which it cannot join4 ,if1 while welding1 a spot appears which does not unite with the weld1 it may be handled by heating all around it to a white heat and then immediately welding the bad place4 ,illustration3 ,figure #ch4--,welding at an ,angle ,never stop in the middle of a weld1 as it is extremely difficult to continue smoothly when resuming work4 ,the ,flame4--,the welding flame must have exactly the right proportions of each gas4 ,if there is too much oxygen1 the metal will be burned or oxidized2 the presence of too much acetylene carbonizes the metal2 that is to say1 it adds carbon and makes the work harder4 ,just the right mixture will neither burn nor carbonize and is said to be a neutral flame4 ,the neutral flame1 if of the correct size for the work1 reduces the metal to a melted condition1 not too fluid1 and for a width about the same as the thickness of the metal being welded4 ,when ready to light the torch1 after attaching the right tip or head as directed in accordance with the thickness of metal to be handled1 it will be necessary to regulate the pressure of gases to secure the neutral flame4 ,the oxygen will have a pressure of from #b to #bj pounds1 according to the nozzle used4 ,the acetylene will have much less4 ,even with the compressed gas1 the pressure should never exceed #aj pounds for the largest work1 and it will usually be from #d to #f4 ,in low pressure systems1 the acetylene will be received at generator pressure4 ,it should first be seen that the hand-screws on the regulators are turned way out so that the springs are free from any tension4 ,it will do no harm if these screws are turned back until they come out of the threads4 ,this must be done with both oxygen and acetylene regulators4 ,next1 open the valve from the generator1 or on the acetylene tank1 and carefully note whether there is any odor of escaping gas4 ,any leakage of this gas must be stopped before going on with the work4 ,the hand wheel controlling the oxygen cylinder valve should now be turned very slowly to the left as far as it will go1 which opens the valve1 and it should be borne in mind the pressure that is being released4 ,turn in the hand screw on the oxygen regulator until the small pressure gauge shows a reading according to the requirements of the nozzle being used4 ,this oxygen regulator adjustment should be made with the cock on the torch open1 and after the regulator is thus adjusted the torch cock may be closed4 ,open the acetylene cock on the torch and screw in on the acetylene regulator hand-screw until gas commences to come through the torch4 ,light this flow of acetylene and adjust the regulator screw to the pressure desired1 or1 if there is no gauge1 so that there is a good full flame4 ,with the pressure of acetylene controlled by the type of generator it will only be necessary to open the torch cock4 ,with the acetylene burning1 slowly open the oxygen cock on the torch and allow this gas to join the flame4 ,the flame will turn intensely bright and then blue white4 ,there will be an outer flame from four to eight inches long and from one to three inches thick4 ,inside of this flame will be two more rather distinctly defined flames4 ,the inner one at the torch tip is very small1 and the intermediate one is long and pointed4 ,the oxygen should be turned on until the two inner flames unite into one blue-white cone from one-fourth to one-half inch long and one-eighth to one-fourth inch in diameter4 ,if this single1 clearly defined cone does not appear when the oxygen torch cock has been fully opened1 turn off some of the acetylene until it does appear4 ,if too much oxygen is added to the flame1 there will still be the central blue-white cone1 but it will be smaller and more or less ragged around the edges 7,figure #ci74 ,when there is just enough oxygen to make the single cone1 and when1 by turning on more acetylene or by turning off oxygen1 two cones are caused to appear1 the flame is neutral 7,figure #dj71 and the small blue-white cone is called the welding flame4 ,illustration3 ,figure #ci4--,oxidizing ,flame--,too ,much ,oxygen ,illustration3 ,figure #dj4--,neutral ,flame ,illustration3 ,figure #da4--,reducing ,flame--,showing an ,excess of ,acetylene ,while welding1 test the correctness of the flame adjustment occasionally by turning on more acetylene or by turning off some oxygen until two flames or cones appear4 ,then regulate as before to secure the single distinct cone4 ,too much oxygen is not usually so harmful as too much acetylene1 except with aluminum4 7,see ,figure #da47 ,an excessive amount of sparks coming from the weld denotes that there is too much oxygen in the flame4 ,should the opening in the tip become partly clogged1 it will be difficult to secure a neutral flame and the tip should be cleaned with a brass or copper wire--never with iron or steel tools or wire of any kind4 ,while the torch is doing its work1 the tip may become excessively hot due to the heat radiated from the molten metal4 ,the tip may be cooled by turning off the acetylene and dipping in water with a slight flow of oxygen through the nozzle to prevent water finding its way into the mixing chamber4 ,the regulators for cutting are similar to those for welding1 except that higher pressures may be handled1 and they are fitted with gauges reading up to #bjj or #bej pounds pressure4 ,in welding metals which conduct the heat very rapidly it is necessary to use a much larger nozzle and flame than for metals which have not this property4 ,this peculiarity is found to the greatest extent in copper1 aluminum and brass4 ,should a hole be blown through the work1 it may be closed by withdrawing the flame for a few seconds and then commencing to build additional metal around the edges1 working all the way around and finally closing the small opening left at the center with a drop or two from the welding rod4 ,,welding ,,various ,,metals ,because of the varying melting points1 rates of expansion and contraction1 and other peculiarities of different metals1 it is necessary to give detailed consideration to the most important ones4 ,characteristics of ,metals4--,the welder should thoroughly understand the peculiarities of the various metals with which he has to deal4 ,the metals and their alloys are described under this heading in the first chapter of this book and a tabulated list of the most important points relating to each metal will be found at the end of the present chapter4 ,all this information should be noted by the operator of a welding installation before commencing actual work4 ,because of the nature of welding1 the melting point of a metal is of great importance4 ,a metal melting at a low temperature should have more careful treatment to avoid undesired flow than one which melts at a temperature which is relatively high4 ,when two dissimilar metals are to be joined1 the one which melts at the higher temperature must be acted upon by the flame first and when it is in a molten condition the heat contained in it will in many cases be sufficient to cause fusion of the lower melting metal and allow them to unite without playing the flame on the lower metal to any great extent4 ,the heat conductivity bears a very important relation to welding1 inasmuch as a metal with a high rate of conductance requires more protection from cooling air currents and heat radiation than one not having this quality to such a marked extent4 ,a metal which conducts heat rapidly will require a larger volume of flame1 a larger nozzle1 than otherwise1 this being necessary to supply the additional heat taken away from the welding point by this conductance4 ,the relative rates of expansion of the various metals under heat should be understood in order that parts made from such material may have proper preparation to compensate for this expansion and contraction4 ,parts made from metals having widely varying rates of expansion must have special treatment to allow for this quality1 otherwise breakage is sure to occur4 ,cast ,iron4--,all spoiled metal should be cut away and if the work is more than one-eighth inch in thickness the sides of the crack should be beveled to a #de degree angle1 leaving a number of points touching at the bottom of the bevel so that the work may be joined in its original relation4 ,the entire piece should be preheated in a bricked-up oven or with charcoal placed on the forge1 when size does not warrant building a temporary oven4 ,the entire piece should be slowly heated and the portion immediately surrounding the weld should be brought to a dull red4 ,care should be used that the heat does not warp the metal through application to one part more than the others4 ,after welding1 the work should be slowly cooled by covering with ashes1 slaked lime1 asbestos fibre or some other non-conductor of heat4 ,these precautions are absolutely essential in the case of cast iron4 ,a neutral flame1 from a nozzle proportioned to the thickness of the work1 should be held with the point of the blue-white cone about one-eighth inch from the surface of the iron4 ,a cast iron rod of correct diameter1 usually made with an excess of silicon1 is used by keeping its end in contact with the molten metal and flowing it into the puddle formed at the point of fusion4 ,metal should be added so that the weld stands about one-eighth inch above the surrounding surface of the work4 ,various forms of flux may be used and they are applied by dipping the end of the welding rod into the powder at intervals4 ,these powders may contain borax or salt1 and to prevent a hard1 brittle weld1 graphite or ferro-silicon may be added4 ,flux should be added only after the iron is molten and as little as possible should be used4 ,no flux should be used just before completion of the work4 ,the welding flame should be played on the work around the crack and gradually brought to bear on the work4 ,the bottom of the bevel should be joined first and it will be noted that the cast iron tends to run toward the flame1 but does not stick together easily4 ,a hard and porous weld should be carefully guarded against1 as described above1 and upon completion of the work the welded surface should be scraped with a file1 while still red hot1 in order to remove the surface scale4 ,malleable ,iron4--,this material should be beveled in the same way that cast iron is handled1 and preheating and slow cooling are equally desirable4 ,the flame used is the same as for cast iron and so is the flux4 ,the welding rod may be of cast iron1 although better results are secured with ,norway iron wire or else a mild steel wire wrapped with a coil of copper wire4 ,it will be understood that malleable iron turns to ordinary cast iron when melted and cooled4 ,welds in malleable iron are usually far from satisfactory and a better joint is secured by brazing the edges together with bronze4 ,the edges to be joined are brought to a heat just a little below the point at which they will flow and the opening is then quickly-filled from a rod of ,tobin bronze or manganese bronze1 a brass or bronze flux being used in this work4 ,wrought ,iron or ,semi-,steel4--,this metal should be beveled and heated in the same way as described for cast iron4 ,the flame should be neutral1 of the same size as for steel1 and used with the tip of the blue-white cone just touching the work4 ,the welding rod should be of mild steel1 or1 if wrought iron is to be welded to steel1 a cast iron rod may be used4 ,a cast iron flux is well suited for this work4 ,it should be noted that wrought iron turns to ordinary cast iron if kept heated for any length of time4 ,steel4--,steel should be beveled if more than one-eighth inch in thickness4 ,it requires only a local preheating around the point to be welded4 ,the welding flame should be absolutely neutral1 without excess of either gas4 ,if the metal is one-sixteenth inch or less in thickness1 the tip of the blue-white cone must be held a short distance from the surface of the work2 in all other cases the tip of this cone is touched to the metal being welded4 ,the welding rod may be of mild1 low carbon steel or of ,norway iron4 ,nickel steel rods may be used for parts requiring great strength1 but vanadium alloys are very difficult to handle4 ,a very satisfactory rod is made by twisting together two wires of the required material4 ,the rod must be kept constantly in contact with the work and should not be added until the edges are thoroughly melted4 ,the flux may or may not be used4 ,if one is wanted1 it may be made from three parts iron filings1 six parts borax and one part sal ammoniac4 ,it will be noticed that the steel runs from the flame1 but tends to hold together4 ,should foaming commence in the molten metal1 it shows an excess of oxygen and that the metal is being burned4 ,high carbon steels are very difficult to handle4 ,it is claimed that a drop or two of copper added to the weld will assist the flow1 but will also harden the work4 ,an excess of oxygen reduces the amount of carbon and softens the steel1 while an excess of acetylene increases the proportion of carbon and hardens the metal4 ,high speed steels may sometimes be welded if first coated with semi-steel before welding4 ,aluminum4--,this is the most difficult of the commonly found metals to weld4 ,this is caused by its high rate of expansion and contraction and its liability to melt and fall away from under the flame4 ,the aluminum seems to melt on the inside first1 and1 without previous warning1 a portion of the work will simply vanish from in front of the operator's eyes4 ,the metal tends to run from the flame and separate at the same time4 ,to keep the metal in shape and free from oxide1 it is worked or puddled while in a plastic condition by an iron rod which has been flattened at one end4 ,several of these rods should be at hand and may be kept in a jar of salt water while not being used4 ,these rods must not become coated with aluminum and they must not get red hot while in the weld4 ,the surfaces to be joined1 together with the adjacent parts1 should be cleaned thoroughly and then washed with a #be per cent solution of nitric acid in hot water1 used on a swab4 ,the parts should then be rinsed in clean water and dried with sawdust4 ,it is also well to make temporary fire clay moulds back of the parts to be heated1 so that the metal may be flowed into place and allowed to cool without danger of breakage4 ,aluminum must invariably be preheated to about #fjj degrees1 and the whole piece being handled should be well covered with sheet asbestos to prevent excessive heat radiation4 ,the flame is formed with an excess of acetylene such that the second cone extends about an inch1 or slightly more1 beyond the small blue-white point4 ,the torch should be held so that the end of this second cone is in contact with the work1 the small cone ordinarily used being kept an inch or an inch and a half from the surface of the work4 ,welding rods of special aluminum are used and must be handled with their end submerged in the molten metal of the weld at all times4 ,when aluminum is melted it forms alumina1 an oxide of the metal4 ,this alumina surrounds small masses of the metal1 and as it does not melt at temperatures below #ejjj degrees 7while aluminum melts at about #abjj71 it prevents a weld from being made4 ,the formation of this oxide is retarded and the oxide itself is dissolved by a suitable flux1 which usually contains phosphorus to break down the alumina4 ,copper4--,the whole piece should be preheated and kept well covered while welding4 ,the flame must be much larger than for the same thickness of steel and neutral in character4 ,a slight excess of acetylene would be preferable to an excess of oxygen1 and in all cases the molten metal should be kept enveloped with the flame4 ,the welding rod is of copper which contains phosphorus2 and a flux1 also containing phosphorus1 should be spread for about an inch each side of the joint4 ,these assist in preventing oxidation1 which is sure to occur with heated copper4 ,copper breaks very easily at a heat slightly under the welding temperature and after cooling it is simply cast copper in all cases4 ,brass and ,bronze4--,it is necessary to preheat these metals1 although not to a very high temperature4 ,they must be kept well covered at all times to prevent undue radiation4 ,the flame should be produced with a nozzle one size larger than for the same thickness of steel and the small blue-white cone should be held from one-fourth to one-half inch above the surface of the work4 ,the flame should be neutral in character4 ,a rod or wire of soft brass containing a large percentage of zinc is suitable for adding to brass1 while copper requires the use of copper or manganese bronze rods4 ,special flux or borax may be used to assist the flow4 ,the emission of white smoke indicates that the zinc contained in these alloys is being burned away and the heat should immediately be turned away or reduced4 ,the fumes from brass and bronze welding are very poisonous and should not be breathed4 ,,restoration ,,of ,,steel ,the result of the high heat to which the steel has been subjected is that it is weakened and of a different character than before welding4 ,the operator may avoid this as much as possible by first playing the outer flame of the torch all over the surfaces of the work just completed until these faces are all of uniform color1 after which the metal should be well covered with asbestos and allowed to cool without being disturbed4 ,if a temporary heating oven has been employed1 the work and oven should be allowed to cool together while protected with the sheet asbestos4 ,if the outside air strikes the freshly welded work1 even for a moment1 the result will be breakage4 ,a weld in steel will always leave the metal with a coarse grain and with all the characteristics of rather low grade cast steel4 ,as previously mentioned in another chapter1 the larger the grain size in steel the weaker the metal will be1 and it is the purpose of the good workman to avoid1 as far as possible1 this weakening4 ,the structure of the metal in one piece of steel will differ according to the heat that it has under gone4 ,the parts of the work that have been at the melting point will1 therefore1 have the largest grain size and the least strength4 ,those parts that have not suffered any great rise in temperature will be practically unaffected1 and all the parts between these two extremes will be weaker or stronger according to their distance from the weld itself4 ,to restore the steel so that it will have the best grain size1 the operator may resort to either of two methods3 7#a7 ,the grain may be improved by forging4 ,that means that the metal added to the weld and the surfaces that have been at the welding heat are hammered much as a blacksmith would hammer his finished work to give it greater strength4 ,the hammering should continue from the time the metal first starts to cool until it has reached the temperature at which the grain size is best for strength4 ,this temperature will vary somewhat with the composition of the metal being handled1 but in a general way1 it may be stated that the hammering should continue without intermission from the time the flame is removed from the weld until the steel just begins to show attraction for a magnet presented to it4 ,this temperature of magnetic attraction will always be low enough and the hammering should be immediately discontinued at this point4 7#b7 ,a method that is more satisfactory1 although harder to apply1 is that of reheating the steel to a certain temperature throughout its whole mass where the heat has had any effect1 and then allowing slow and even cooling from this temperature4 ,the grain size is affected by the temperature at which the reheating is stopped1 and not by the cooling1 yet the cooling should be slow enough to avoid strains caused by uneven contraction4 ,after the weld has been completed the steel must be allowed to cool until below #abjj ,fahrenheit4 ,the next step is to heat the work slowly until all those parts to be restored have reached a temperature at which the magnet just ceases to be attracted4 ,while the very best temperature will vary according to the nature and hardness of the steel being handled1 it will be safe to carry the heating to the point indicated by the magnet in the absence of suitable means of measuring accurately these high temperatures4 ,in using a magnet for testing1 it will be most satisfactory if it is an electromagnet and not of the permanent type4 ,the electric current may be secured from any small battery and will be the means of making sure of the test4 ,the permanent magnet will quickly lose its power of attraction under the combined action of the heat and the jarring to which it will be subjected4 ,in reheating the work it is necessary to make sure that no part reaches a temperature above that desired for best grain size and also to see that all parts are brought to this temperature4 ,here enters the greatest difficulty in restoring the metal4 ,the heating may be done so slowly that no part of the work on the outside reaches too high a temperature and then keeps the outside at this heat until the entire mass is at the same temperature4 ,a less desirable way is to heat the outside higher than this temperature and allow the conductivity of the metal to distribute the excess to the inside4 ,the most satisfactory method1 where it can be employed1 is to make use of a bath of some molten metal or some chemical mixture that can be kept at the exact heat necessary by means of gas fires that admit of close regulation4 ,the temperature of these baths may be maintained at a constant point by watching a pyrometer1 and the finished work may be allowed to remain in the bath until all parts have reached the desired temperature4 ,,welding ,,information ,the following tables include much of the information that the operator must use continually to handle the various metals successfully4 ,the temperature scales are given for convenience only4 ,the composition of various alloys will give an idea of the difficulties to be contended with by consulting the information on welding various metals4 ,the remaining tables are of self-evident value in this work4 ,,temperature ,,scales ,centigrade ,fahrenheit ,centigrade ,fahrenheit #bjj #cib #ajjj #ahcb #bbe #dcg #ajej #aibb #bej #dhb #aajj #bjab #bge #ebg #aaej #bajb #cjj #egb #abjj #baib #cbe #fag #abej #bbhb #cej #ffb #acjj #bcgb #cge #gjg #acej #bdfb #djj #geb #adjj #beeb #dbe #gig #adej #bfdb #dej #hdb #aejj #bgcb #dge #hhg #aeej #bhbb #ejj #icb #afjj #biab #ebe #igg #afej #cjjb #eej #ajbb #agjj #cjib #ege #ajfg #agej #cahb #fjj #aaab #ahjj #cbgb #fbe #aaeg #ahej #ccfb #fej #abjb #aijj #cdeb #fge #abdg #bjjj #cfcb #gjj #abib #bjej #cgbb #gbe #accg #bajj #chab #gej #achb #baej #cijb #gge #adbg #bbjj #ciib #hjj #adgb #bbej #djhb #hbe #aeag #bcjj #dagb #hej #aefb #bcej #dbfb #hge #afjg #bdjj #dceb #ijj #afeb #bdej #dddb #ibe #afig #bejj #decb #iej #agdb #beej #dfbb #ige #aghg #bfjj #dgab ,,metal ,,alloys 7,society of ,automobile ,engineers7 ,babbitt-- ,tin444444444444444444444444444 #hd4jj ,antimony4444444444444444444444 #i4jj ,copper444444444444444444444444 #g4jj ,brass1 ,white-- ,copper444444444444444444444444 #c4jj to #f4jj ,tin 7minimum7 4444444444444444 #fe4jj ,zinc44444444444444444444444444 #bh4jj to #cj4jj ,brass1 ,red ,cast-- ,copper444444444444444444444444 #he4jj ,tin444444444444444444444444444 #e4jj ,lead44444444444444444444444444 #e4jj ,zinc44444444444444444444444444 #e4jj ,brass1 ,yellow-- ,copper444444444444444444444444 #fb4jj to #fe4jj ,lead44444444444444444444444444 #b4jj to #d4jj ,zinc44444444444444444444444444 #cf4jj to #ca4jj ,bronze1 ,hard-- ,copper444444444444444444444444 #hg4jj to #hh4jj ,tin444444444444444444444444444 #i4ej to #aj4ej ,zinc44444444444444444444444444 #a4ej to #b4ej ,bronze1 ,phosphor-- ,copper444444444444444444444444 #hj4jj ,tin444444444444444444444444444 #aj4jj ,lead44444444444444444444444444 #aj4jj ,phosphorus44444444444444444444 4#ej to 4#be ,bronze1 ,manganese-- ,copper 7approximate7 444444444 #fj4jj ,zinc 7approximate7 44444444444 #dj4jj ,manganese 7variable7 444444444 small ,bronze1 ,gear-- ,copper444444444444444444444444 #hh4jj to #hi4jj ,tin444444444444444444444444444 #aa4jj to #ab4jj ,aluminum ,alloys-- ,aluminum ,copper ,zinc ,manganese ,no4 #a44 #ij4jj #h4e-g4j ,no4 #b44 #hj4jj #b4j-c4j #ae ,not over #j4dj ,no4 #c44 #fe4jj #ce4j ,cast ,iron-- ,gray ,iron ,malleable ,total carbon44444444#c4j to #c4e ,combined carbon44444#j4d to #j4g ,manganese44444444444#j4d to #j4g #j4c to #j4g ,phosphorus4444444444#j4f to #a4j ,not over #j4b ,sulphur44444444444,not over #j4a ,not over #j4f ,silicon444444444444#a4ge to #b4be ,not over #a4j ,carbon ,steel 7#aj ,point7-- ,carbon444444444444444444444444 4#je to 4#ae ,manganese444444444444444444444 4#cj to 4#fj ,phosphorus 7maximum74444444444 4#jde ,sulphur 7maximum74444444444444 4#je 7#bj ,point7-- ,carbon444444444444444444444444 4#ae to 4#be ,manganese444444444444444444444 4#cj to 4#fj ,phosphorus 7maximum74444444444 4#jde ,sulphur 7maximum74444444444444 4#je 7#ce ,point7-- ,manganese444444444444444444444 4#ej to 4#hj ,carbon444444444444444444444444 4#cj to 4#dj ,phosphorus 7maximum74444444444 4#je ,sulphur 7maximum74444444444444 4#je 7#ie ,point7-- ,carbon444444444444444444444444 4#ij to #a4je ,manganese444444444444444444444 4#be to 4#ej ,phosphorus 7maximum74444444444 4#jd ,sulphur 7maximum74444444444444 4#je ,,heating ,,power ,,of ,,fuel ,,gases 7,in ,b4,t4,u4 per ,cubic ,foot47 ,acetylene4444444 #adih4ii ,ethylene4444444 #aefb4i ,hydrogen44444444 #bia4if ,methane44444444 #iec4f ,alcohol444444444 #aeja4gf ,,melting ,,points ,,of ,,metals ,platinum44444444444444444444#cbjj ,iron1 wrought444444444444444#bijj malleable44444444444444444#bejj cast4444444444444444444444#bdjj pure4444444444444444444444#bgfj ,steel1 mild44444444444444444#bgjj ,medium44444444444444444444#bfjj ,hard4444444444444444444444#bejj ,copper4444444444444444444444#aiej ,brass44444444444444444444444#ahjj ,silver4444444444444444444444#agej ,bronze4444444444444444444444#agjj ,aluminum44444444444444444444#aage ,antimony44444444444444444444#aaej ,zinc444444444444444444444444 #hjj ,lead444444444444444444444444 #fbj ,babbitt444444444444444444#ejj-gjj ,solder4444444444444444444#ejj-ege ,tin4444444444444444444444444 #dej ,,note4--,these melting points are for average compositions and conditions4 ,the exact proportion of elements entering into the metals affects their melting points one way or the other in practice4 ,,tensile ,,strength ,,of ,,metals ,alloy steels can be made with tensile strengths as high as #cjj1jjj pounds per square inch4 ,some carbon steels are given below according to points3 ,pounds per ,square ,inch ,steel1 #aj point4444444444444444 #ej1jjj to #fe1jjj #bj point444444444444444444444 #fj1jjj to #hj1jjj #dj point444444444444444444444 #gj1jjj to #ajj1jjj #fj point444444444444444444444 #ij1jjj to #abj1jjj ,iron1 ,cast444444444444444444444 #ac1jjj to #cj1jjj ,wrought4444444444444444444444 #dj1jjj to #fj1jjj ,malleable44444444444444444444 #be1jjj to #de1jjj ,copper4444444444444444444444444 #bd1jjj to #ej1jjj ,bronze4444444444444444444444444 #cj1jjj to #fj1jjj ,brass1 ,cast44444444444444444444 #ab1jjj to #ah1jjj ,rolled44444444444444444444444 #cj1jjj to #dj1jjj ,wire4444444444444444444444444 #fj1jjj to #ge1jjj ,aluminum44444444444444444444444 #ab1jjj to #bc1jjj ,zinc444444444444444444444444444 #e1jjj to #ae1jjj ,tin4444444444444444444444444444 #c1jjj to #e1jjj ,lead444444444444444444444444444 #a1ejj to #b1ejj ,,conductivity ,,of ,,metals 7,based on the ,value of ,silver as #ajj7 ,heat ,electricity ,silver44444444444444444444#ajj #ajj ,copper44444444444444444444 #gd #ii ,aluminum444444444444444444 #ch #fc ,brass444444444444444444444 #bc #bb ,zinc4444444444444444444444 #ai #bi ,tin44444444444444444444444 #ad #ae ,wrought ,iron44444444444444 #ab #af ,steel444444444444444444444 #aa4e #ab ,cast ,iron44444444444444444 #aa #ab ,bronze44444444444444444444 #i #g ,lead4444444444444444444444 #h #i ,,weight ,,of ,,metals 7,per ,cubic ,inch7 ,pounds ,pounds ,lead444444444444 4#daj ,wrought ,iron44444 4#bgh ,copper4444444444 4#cbj ,tin44444444444444 4#bfc ,bronze4444444444 4#cac ,cast ,iron44444444 4#bfj ,brass44444444444 4#cjj ,zinc4444444444444 4#beh ,steel44444444444 4#bhc ,aluminum444444444 4#jic ,,expansion ,,of ,,metals 7,measured in ,thousandths of an ,inch per ,foot of ,length ,when ,raised #ajjj ,degrees in ,temperature7 ,inch ,inch ,lead444444444444 4#ahh ,brass444444444444 4#aae ,zinc444444444444 4#afh ,copper44444444444 4#ajf ,aluminum44444444 4#adh ,steel444444444444 4#jhc ,silver4444444444 4#abi ,wrought ,iron44444 4#jgh ,bronze4444444444 4#aah ,cast ,iron44444444 4#jfh ,,chapter ,,vi ,,electric ,,welding ,,resistance ,,method ,two distinct forms of electric welding apparatus are in use1 one producing heat by the resistance of the metal being treated to the passage of electric current1 the other using the heat of the electric arc4 ,the resistance process is of the greatest use in manufacturing lines where there is a large quantity of one kind of work to do1 many thousand pieces of one kind1 for instance4 ,the arc method may be applied in practically any case where any other form of weld may be made4 ,the resistance process will be described first4 ,it is a well known fact that a poor conductor of electricity will offer so much resistance to the flow of electricity that it will heat4 ,copper is a good conductor1 and a bar of iron1 a comparatively poor conductor1 when placed between heavy copper conductors of a welder1 becomes heated in attempting to carry the large volume of current4 ,the degree of heat depends on the amount of current and the resistance of the conductor4 ,in an electric circuit the ends of two pieces of metal brought together form the point of greatest resistance in the electric circuit1 and the abutting ends instantly begin to heat4 ,the hotter this metal becomes1 the greater the resistance to the flow of current2 consequently1 as the edges of the abutting ends heat1 the current is forced into the adjacent cooler parts1 until there is a uniform heat throughout the entire mass4 ,the heat is first developed in the interior of the metal so that it is welded there as perfectly as at the surface4 ,illustration3 ,figure #db4--,spot ,welding ,machine ,the electric welder 7,figure #db7 is built to hold the parts to be joined between two heavy copper dies or contacts4 ,a current of three to five volts1 but of very great volume 7amperage71 is allowed to pass across these dies1 and in going through the metal to be welded1 heats the edges to a welding temperature4 ,it may be explained that the voltage of an electric current measures the pressure or force with which it is being sent through the circuit and has nothing to do with the quantity or volume passing4 ,amperes measure the rate at which the current is passing through the circuit and consequently give a measure of the quantity which passes in any given time4 ,volts correspond to water pressure measured by pounds to the square inch2 amperes represent the flow in gallons per minute4 ,the low voltage used avoids all danger to the operator1 this pressure not being sufficient to be felt even with the hands resting on the copper contacts4 ,current is supplied to the welding machine at a higher voltage and lower amperage than is actually used between the dies1 the low voltage and high amperage being produced by a transformer incorporated in the machine itself4 ,by means of windings of suitable size wire1 the outside current may be received at voltages ranging from #aaj to #eej and converted to the low pressure needed4 ,the source of current for the resistance welder must be alternating1 that is1 the current must first be negative in value and then positive1 passing from one extreme to the other at rates varying from #be to #acc times a second4 ,this form is known as alternating current1 as opposed to direct current1 in which there is no changing of positive and negative4 ,the current must also be what is known as single phase1 that is1 a current which rises from zero in value to the highest point as a positive current and then recedes to zero before rising to the highest point of negative value4 ,two-phase of three-phase currents would give two or three positive impulses during this time4 ,as long as the current is single phase alternating1 the voltage and cycles 7number of alternations per second7 may be anything convenient4 ,various voltages and cycles are taken care of by specifying all these points when designing the transformer which is to handle the current4 ,direct current is not used because there is no way of reducing the voltage conveniently without placing resistance wires in the circuit and this uses power without producing useful work4 ,direct current may be changed to alternating by having a direct current motor running an alternating current dynamo1 or the change may be made by a rotary converter1 although this last method is not so satisfactory as the first4 ,the voltage used in welding being so low to start with1 it is absolutely necessary that it be maintained at the correct point4 ,if the source of current supply is not of ample capacity for the welder being used1 it will be very hard to avoid a fall of voltage when the current is forced to pass through the high resistance of the weld4 ,the current voltage for various work is calculated accurately1 and the efficiency of the outfit depends to a great extent on the voltage being constant4 ,a simple test for fall of voltage is made by connecting an incandescent electric lamp across the supply lines at some point near the welder4 ,the lamp should burn with the same brilliancy when the weld is being made as at any other time4 ,if the lamp burns dim at any time1 it indicates a drop in voltage1 and this condition should be corrected4 ,the dynamo furnishing the alternating current may be in the same building with the welder and operated from a direct current motor1 as mentioned above1 or operated from any convenient shafting or source of power4 ,when the dynamo is a part of the welding plant it should be placed as close to the welding machine as possible1 because the length of the wire used affects the voltage appreciably4 ,in order to hold the voltage constant1 the ,toledo ,electric ,welder ,company has devised connections which include a rheostat to insert a variable resistance in the field windings of the dynamo so that the voltage may be increased by cutting this resistance out at the proper time4 ,an auxiliary switch is connected to the welder switch so that both switches act together4 ,when the welder switch is closed in making a weld1 that portion of the rheostat resistance between two arms determining the voltage is short circuited4 ,this lowers the resistance and the field magnets of the dynamo are made stronger so that additional voltage is provided to care for the resistance in the metal being heated4 ,a typical machine is shown in the accompanying cut 7,figure #dc74 ,on top of the welder are two jaws for holding the ends of the pieces to be welded4 ,the lower part of the jaws is rigid while the top is brought down on top of the work1 acting as a clamp4 ,these jaws carry the copper dies through which the current enters the work being handled4 ,after the work is clamped between the jaws1 the upper set is forced closer to the lower set by a long compression lever4 ,the current being turned on with the surfaces of the work in contact1 they immediately heat to the welding point when added pressure on the lever forces them together and completes the weld4 ,illustration3 ,figure #dc--,operating ,parts of a ,toledo ,spot ,welder ,illustration3 ,figure #dc;a4--,method of ,testing ,electric ,welder ,illustration3 ,figure #dd4--;,detail of ,water-,cooled ,spot ,welding ,head ,the transformer is carried in the base of the machine and on the left-hand side is a regulator for controlling the voltage for various kinds of work4 ,the clamps are applied by treadles convenient to the foot of the operator4 ,a treadle is provided which instantly releases both jaws upon the completion of the weld4 ,one or both of the copper dies may be cooled by a stream of water circulating through it from the city water mains 7,figure #dd74 ,the regulator and switch give the operator control of the heat1 anything from a dull red to the melting point being easily obtained by movement of the lever 7figure #de74 ,illustration3 ,figure #de4--,welding ,head of a ,water-,cooled ,welder ,welding4--,it is not necessary to give the metal to be welded any special preparation1 although when very rusty or covered with scale1 the rust and scale should be removed sufficiently to allow good contact of clean metal on the copper dies4 ,the cleaner and better the stock1 the less current it takes1 and there is less wear on the dies4 ,the dies should be kept firm and tight in their holders to make a good contact4 ,all bolts and nuts fastening the electrical contacts should be clean and tight at all times4 ,the scale may be removed from forgings by immersing them in a pickling solution in a wood1 stone or lead-lined tank4 ,the solution is made with five gallons of commercial sulphuric acid in #aej gallons of water4 ,to get the quickest and best results from this method1 the solution should be kept as near the boiling point as possible by having a coil of extra heavy lead pipe running inside the tank and carrying live steam4 ,a very few minutes in this bath will remove the scale and the parts should then be washed in running water4 ,after this washing they should be dipped into a bath of #ej pounds of unslaked lime in #aej gallons of water to neutralize any trace of acid4 ,cast iron cannot be commercially welded1 as it is high in carbon and silicon1 and passes suddenly from a crystalline to a fluid state when brought to the welding temperature4 ,with steel or wrought iron the temperature must be kept below the melting point to avoid injury to the metal4 ,the metal must be heated quickly and pressed together with sufficient force to push all burnt metal out of the joint4 ,high carbon steel can be welded1 but must be annealed after welding to overcome the strains set up by the heat being applied at one place4 ,good results are hard to obtain when the carbon runs as high as #ge points1 and steel of this class can only be handled by an experienced operator4 ,if the steel is below #be points in carbon content1 good welds will always be the result4 ,to weld high carbon to low carbon steel1 the stock should be clamped in the dies with the low carbon stock sticking considerably further out from the die than the high carbon stock4 ,nickel steel welds readily1 the nickel increasing the strength of the weld4 ,iron and copper may be welded together by reducing the size of the copper end where it comes in contact with the iron4 ,when welding copper and brass the pressure must be less than when welding iron4 ,the metal is allowed to actually fuse or melt at the juncture and the pressure must be sufficient to force the burned metal out4 ,the current is cut off the instant the metal ends begin to soften1 this being done by means of an automatic switch which opens when the softening of the metal allows the ends to come together4 ,the pressure is applied to the weld by having the sliding jaw moved by a weight on the end of an arm4 ,copper and brass require a larger volume of current at a lower voltage than for steel and iron4 ,the die faces are set apart three times the diameter of the stock for brass and four times the diameter for copper4 ,light gauges of sheet steel can be welded to heavy gauges or to solid bars of steel by spot welding1 which will be described later4 ,galvanized iron can be welded1 but the zinc coating will be burned off4 ,sheet steel can be welded to cast iron1 but will pull apart1 tearing out particles of the iron4 ,sheet copper and sheet brass may be welded1 although this work requires more experience than with iron and steel4 ,some grades of sheet aluminum can be spot-welded if the slight roughness left on the surface under the die is not objectionable4 ,butt ,welding4--,this is the process which joins the ends of two pieces of metal as described in the foregoing part of this chapter4 ,the ends are in plain sight of the operator at all times and it can easily be seen when the metal reaches the welding heat and begins to soften 7,figure #df74 ,it is at this point that the pressure must be applied with the lever and the ends forced together in the weld4 ,illustration3 ,figure #df4--;,butt ,welder ,the parts are placed in the clamping jaws 7,figure #dg7 with #a_/h to #a_/b inch of metal extending beyond the jaw4 ,the ends of the metal touch each other and the current is turned on by means of a switch4 ,to raise the ends to the proper heat requires from #c seconds for #a_/d-;inch rods to #ce seconds for a #a-a_/b-;inch bar4 ,this method is applicable to metals having practically the same area of metal to be brought into contact on each end4 ,when such parts are forced together a slight projection will be left in the form of a fin or an enlarged portion called an upset4 ,the degree of heat required for any work is found by moving the handle of the regulator one way or the other while testing several parts4 ,when this setting is right the work can continue as long as the same sizes are being handled4 ,illustration3 ,figure #dg4--;,clamping ,dies of a ,butt ,welder ,copper1 brass1 tool steel and all other metals that are harmed by high temperatures must be heated quickly and pressed together with sufficient force to force all burned metal from the weld4 ,in case it is desired to make a weld in the form of a capital letter ,t1 it is necessary to heat the part corresponding to the top bar of the ,t to a bright red1 then bring the lower bar to the pre-heated one and again turn on the current1 when a weld can be quickly made4 ,spot ,welding4--,this is a method of joining metal sheets together at any desired point by a welded spot about the size of a rivet4 ,it is done on a spot welder by fusing the metal at the point desired and at the same instant applying sufficient pressure to force the particles of molten metal together4 ,the dies are usually placed one above the other so that the work may rest on the lower one while the upper one is brought down on top of the upper sheet to be welded4 ,one of the dies is usually pointed slightly1 the opposing one being left flat4 ,the pointed die leaves a slight indentation on one side of the metal1 while the other side is left smooth4 ,the dies may be reversed so that the outside surface of any work may be left smooth4 ,the current is allowed to flow through the dies by a switch which is closed after pressure is applied to the work4 ,there is a limit to the thickness of sheet metal that can be welded by this process because of the fact that the copper rods can only carry a certain quantity of current without becoming unduly heated themselves4 ,another reason is that it is difficult to make heavy sections of metal touch at the welding point without excessive pressure4 ,lap welding is the process used when two pieces of metal are caused to overlap and when brought to a welding heat are forced together by passing through rollers1 or under a press1 thus leaving the welded joint practically the same thickness as the balance of the work4 ,where it is desirable to make a continuous seam1 a special machine is required1 or an attachment for one of the other types4 ,in this form of work the stock must be thoroughly cleaned and is then passed between copper rollers which act in the same capacity as the copper dies4 ,other ,applications4--,hardening and tempering can be done by clamping the work in the welding dies and setting the control and time to bring the metal to the proper color1 when it is cooled in the usual manner4 ,brazing is done by clamping the work in the jaws and heating until the flux1 then the spelter has melted and run into the joint4 ,riveting and heading of rivets can be done by bringing the dies down on opposite ends of the rivet after it has been inserted in the hole1 the dies being shaped to form the heads properly4 ,hardened steel may be softened and annealed so that it can be machined by connecting the dies of the welder to each side of the point to be softened4 ,the current is then applied until the work has reached a point at which it will soften when cooled4 ,troubles and ,remedies4--,the following methods have been furnished by the ,toledo ,electric ,welder ,company and are recommended for this class of work whenever necessary4 ,to locate grounds in the primary or high voltage side of the circuit1 connect incandescent lamps in series by means of a long piece of lamp cord1 as shown1 in ,figure #dc;a4 ,for #aaj volts use one lamp1 for #bbj volts use two lamps and for #ddj volts use four lamps4 ,attach one end of the lamp cord to one side of the switch1 and close the switch4 ,take the other end of the cord in the hand and press it against some part of the welder frame where the metal is clean and bright4 ,paint1 grease and dirt act as insulators and prevent electrical contact4 ,if the lamp lights1 the circuit is in electrical contact with the frame2 in other words1 grounded4 ,if the lamps do not light1 connect the wire to a terminal block1 die or slide4 ,if the lamps then light1 the circuit1 coils or leads are in electrical contact with the large coil in the transformer or its connections4 ,if1 however1 the lamps do not light in either case1 the lamp cord should be disconnected from the switch and connected to the other side1 and the operations of connecting to welder frame1 dies1 terminal blocks1 etc41 as explained above1 should be repeated4 ,if the lamps light at any of these connections1 a ground is indicated4 ,grounds can usually be found by carefully tracing the primary circuit until a place is found where the insulation is defective4 ,reinsulate and make the above tests again to make sure everything is clear4 ,if the ground can not be located by observation1 the various parts of the primary circuit should be disconnected1 and the transformer1 switch1 regulator1 etc41 tested separately4 ,to locate a ground in the regulator or other part1 disconnect the lines running to the welder from the switch4 ,the test lamps used in the previous tests are connected1 one end of lamp cord to the switch1 the other end to a binding post of the regulator4 ,connect the other side of the switch to some part of the regulator housing4 7,this must be a clean connection to a bolt head or the paint should be scraped off47 ,close the switch4 ,if the lamps light1 the regulator winding or some part of the switch is grounded to the iron base or core of the regulator4 ,if the lamps do not light1 this part of the apparatus is clear4 ,this test can be easily applied to any part of the welder outfit by connecting to the current carrying part of the apparatus1 and to the iron base or frame that should not carry current4 ,if the lamps light1 it indicates that the insulation is broken down or is defective4 ,an ,a4,c4 voltmeter can1 of course1 be substituted for the lamps1 or a ,d4,c4 voltmeter with ,d4,c4 current can be used in making the tests4 ,a short circuit in the primary is caused by the insulation of the coils becoming defective and allowing the bare copper wires to touch each other4 ,this may result in a burn out of one or more of the transformer coils1 if the trouble is in the transformer1 or in the continued blowing of fuses in the line4 ,feel of each coil separately4 ,if a short circuit exists in a coil it will heat excessively4 ,examine all the wires2 the insulation may have worn through and two of them may cross1 or be in contact with the frame or other part of the welder4 ,a short circuit in the regulator winding is indicated by failure of the apparatus to regulate properly1 and sometimes1 though not always1 by the heating of the regulator coils4 ,the remedy for a short circuit is to reinsulate the defective parts4 ,it is a good plan to prevent trouble by examining the wiring occasionally and see that the insulation is perfect4 ,to ,locate ,grounds and ,short ,circuits in the ,secondary1 or ,low ,voltage ,side4--,trouble of this kind is indicated by the machine acting sluggish or1 perhaps1 refusing to operate4 ,to make a test1 it will be necessary to first ascertain the exciting current of your particular transformer4 ,this is the current the transformer draws on open circuit1 or when supplied with current from the line with no stock in the welder dies4 ,the following table will give this information close enough for all practical purposes3 ,k4,w4 ----------------- ,amperes at ---------------- ,rating #aaj ,volts #bbj ,volts #ddj ,volts #eej ,volts #c #a4e 4#ge 4#ch 4#c #e #b4e #a4be 4#fc 4#e #h #c4f #a4h 4#i 4#gb #aj #d4be #b4ac #a4jg 4#he #ae #f4 #c4 #a4e #a4b #bj #g4 #c4e #a4ge #a4d #cj #i4 #d4e #b4be #a4h #ce #i4f #d4h #b4d #a4ib #ej #aj4 #e4 #b4e #b ,remove the fuses from the wall switch and substitute fuses just large enough to carry the exciting current4 ,if no suitable fuses are at hand1 fine strands of copper from an ordinary lamp cord may be used4 ,these strands are usually ,no4 #cj gauge wire and will fuse at about #aj amperes4 ,one or more strands should be used1 depending on the amount of exciting current1 and are connected across the fuse clips in place of fuse wire4 ,place a piece of wood or fibre between the welding dies in the welder as though you were going to weld them4 ,see that the regulator is on the highest point and close the welder switch4 ,if the secondary circuit is badly grounded1 current will flow through the ground1 and the small fuses or small strands of wire will burn out4 ,this is an indication that both sides of the secondary circuit are grounded or that a short circuit exists in a primary coil4 ,in either case the welder should not be operated until the trouble is found and removed4 ,if1 however1 the small fuses do not blow1 remove same and replace the large fuses1 then disconnect wires running from the wall switch to the welder and substitute two pieces of ,no4 #h or ,no4 #f insulated copper wire1 after scraping off the insulation for an inch or two at each end4 ,connect one wire from the switch to the frame of welder2 this will leave one loose end4 ,hold this a foot or so away from the place where the insulation is cut off2 then turn on the current and strike the free end of this wire lightly against one of the copper dies1 drawing it away quickly4 ,if no sparking is produced1 the secondary circuit is free from ground1 and you will then look for a broken connection in the circuit4 ,some caution must be used in making the above test1 as in case one terminal is heavily grounded the testing wire may be fused if allowed to stay in contact with the die4 ,the ,remedy4--,clean the slides1 dies and terminal blocks thoroughly and dry out the fibre insulation if it is damp4 ,see that no scale or metal has worked under the sliding parts1 and that the secondary leads do not touch the frame4 ,if the ground is very heavy it may be necessary to remove the slides in order to facilitate the examination and removal of the ground4 ,insulation1 where torn or worn through1 must be carefully replaced or taped4 ,if the transformer coils are grounded to the iron core of the transformer or to the secondary1 it may be necessary to remove the coils and reinsulate them at the points of contact4 ,a short circuited coil will heat excessively and eventually burn out4 ,this may mean a new coil if you are unable to repair the old one4 ,in all cases the transformer windings should be protected from mechanical injury or dampness4 ,unless excessively overloaded1 transformers will last for years without giving a moment's trouble1 if they are not exposed to moisture or are not injured mechanically4 ,the most common trouble arises from poor electrical contacts1 and they are the cause of endless trouble and annoyance4 ,see that all connections are clean and bright4 ,take out the dies every day or two and see that there is no scale1 grease or dirt between them and the holders4 ,clean them thoroughly before replacing4 ,tighten the bolts running from the transformer leads to the work jaws4 ,,electric ,,arc ,,welding ,this method bears no relation to the one just considered1 except that the source of heat is the same in both cases4 ,arc welding makes use of the flame produced by the voltaic arc in practically the same way that oxy-acetylene welding uses the flame from the gases4 ,if the ends of two pieces of carbon through which a current of electricity is flowing while they are in contact are separated from each other quite slowly1 a brilliant arc of flame is formed between them which consists mainly of carbon vapor4 ,the carbons are consumed by combination with the oxygen in the air and through being turned to a gas under the intense heat4 ,the most intense action takes place at the center of the carbon which carries the positive current and this is the point of greatest heat4 ,the temperature at this point in the arc is greater than can be produced by any other means under human control4 ,an arc may be formed between pieces of metal1 called electrodes1 in the same way as between carbon4 ,the metallic arc is called a flaming arc and as the metal of the electrode burns with the heat1 it gives the flame a color characteristic of the material being used4 ,the metallic arc may be drawn out to a much greater length than one formed between carbon electrodes4 ,arc ,welding is carried out by drawing a piece of carbon which is of negative polarity away from the pieces of metal to be welded while the metal is made positive in polarity4 ,the negative wire is fastened to the carbon electrode and the work is laid on a table made of cast or wrought iron to which the positive wire is made fast4 ,the direction of the flame is then from the metal being welded to the carbon and the work is thus prevented from being saturated with carbon1 which would prove very detrimental to its strength4 ,a secondary advantage is found in the fact that the greatest heat is at the metal being welded because of its being the positive electrode4 ,the carbon electrode is usually made from one quarter to one and a half inches in diameter and from six to twelve inches in length4 ,the length of the arc may be anywhere from one inch to four inches1 depending on the size of the work being handled4 ,while the parts are carefully insulated to avoid danger of shock1 it is necessary for the operator to wear rubber gloves as a further protection1 and to wear some form of hood over the head to shield him against the extreme heat liberated4 ,this hood may be made from metal1 although some material that does not conduct electricity is to be preferred4 ,the work is watched through pieces of glass formed with one sheet1 which is either blue or green1 placed over another which is red4 ,screens of glass are sometimes used without the head protector4 ,some protection for the eyes is absolutely necessary because of the intense white light4 ,it is seldom necessary to preheat the work as with the gas processes1 because the heat is localized at the point of welding and the action is so rapid that the expansion is not so great4 ,the necessity of preheating1 however1 depends entirely on the material1 form and size of the work being handled4 ,the same advice applies to arc welding as to the gas flame method but in a lesser degree4 ,filling rods are used in the same way as with any other flame process4 ,it is the purpose of this explanation to state the fundamental principles of the application of the electric arc to welding metals1 and by applying the principles the following questions will be answered3 ,what metals can be welded by the electric arc8 ,what difficulties are to be encountered in applying the electric arc to welding8 ,what is the strength of the weld in comparison with the original piece8 ,what is the function of the arc welding machine itself8 ,what is the comparative application of the electric arc and the oxy-acetylene method and others of a similar nature8 ,the answers to these questions will make it possible to understand the application of this process to any work4 ,in a great many places the use of the arc is cutting the cost of welding to a very small fraction of what it would be by any other method1 so that the importance of this method may be well understood4 ,any two metals which are brought to the melting temperature and applied to each other will adhere so that they are no more apt to break at the weld than at any other point outside of the weld4 ,it is the property of all metals to stick together under these conditions4 ,the electric arc is used in this connection merely as a heating agent4 ,this is its only function in the process4 ,it has advantages in its ease of application and the cheapness with which heat can be liberated at any given point by its use4 ,there is nothing in connection with arc welding that the above principles will not answer2 that is1 that metals at the melting point will weld and that the electric arc will furnish the heat to bring them to this point4 ,as to the first question1 what metals can be welded1 all metals can be welded4 ,the difficulties which are encountered are as follows3 ,in the case of brass or zinc1 the metals will be covered with a coat of zinc oxide before they reach a welding heat4 ,this zinc oxide makes it impossible for two clean surfaces to come together and some method has to be used for eliminating this possibility and allowing the two surfaces to join without the possibility of the oxide intervening4 ,the same is true of aluminum1 in which the oxide1 alumina1 will be formed1 and with several other alloys comprising elements of different melting points4 ,in order to eliminate these oxides1 it is necessary in practical work1 to puddle the weld2 this is1 to have a sufficient quantity of molten metal at the weld so that the oxide is floated away4 ,when this is done1 the two surfaces which are to be joined are covered with a coat of melted metal on which floats the oxide and other impurities4 ,the two pieces are thus allowed to join while their surfaces are protected4 ,this precaution is not necessary in working with steel except in extreme cases4 ,another difficulty which is met with in the welding of a great many metals is their expansion under heat1 which results in so great a contraction when the weld cools that the metal is left with a considerable strain on it4 ,in extreme cases this will result in cracking at the weld or near it4 ,to eliminate this danger it is necessary to apply heat either all over the piece to be welded or at certain points4 ,in the case of cast iron and sometimes with copper it is necessary to anneal after welding1 since otherwise the welded pieces will be very brittle on account of the chilling4 ,this is also true of malleable iron4 ,very thin metals which are welded together and are not backed up by something to carry away the excess heat1 are very apt to burn through1 leaving a hole where the weld should be4 ,this difficulty can be eliminated by backing up the weld with a metal face or by decreasing the intensity of the arc so that this melting through will not occur4 ,however1 the practical limit for arc welding without backing up the work with a metal face or decreasing the intensity of the arc is approximately #bb gauge1 although thinner metal can be welded by a very skillful and careful operator4 ,one difficulty with arc welding is the lack of skillful operators4 ,this method is often looked upon as being something out of the ordinary and governed by laws entirely different from other welding4 ,as a matter of fact1 it does not take as much skill to make a good arc weld as it does to make a good weld in a forge fire as the blacksmith does it4 ,there are few jobs which cannot be handled successfully by an operator of average intelligence with one week's instructions1 although his work will become better and better in quality as he continues to use the arc4 ,now comes the question of the strength of the weld after it has been made4 ,this strength is equally as great as that of the metal that is used to make the weld4 ,it should be remembered1 however1 that the metal which goes into the weld is put in there as a casting and has not been rolled4 ,this would make the strength of the weld as great as the same metal that is used for filling if in the cast form4 ,two pieces of steel could be welded together having a tensile strength at the weld of #ej1jjj pounds4 ,higher strengths than this can be obtained by the use of special alloys for the filling material or by rolling4 ,welds with a tensile strength as great as mentioned will give a result which is perfectly satisfactory in almost all cases4 ,there are a great many jobs where it is possible to fill up the weld1 that is1 make the section at the point of the weld a little larger than the section through the rest of the piece4 ,by doing this1 the disadvantages of the weld being in the form of a casting in comparison with the rest of the piece being in the form of rolled steel can be overcome1 and make the weld itself even stronger than the original piece4 ,the next question is the adaptability of the electric arc in comparison with forge fire1 oxy-acetylene or other method4 ,the answer is somewhat difficult if made general4 ,there are no doubt some cases where the use of a drop hammer and forge fire or the use of the oxy-acetylene torch will make1 all things being considered1 a better job than the use of the electric arc1 although a case where this is absolutely proved is rare4 ,the electric arc will melt metal in a weld for less than the same metal can be melted by the use of the oxy-acetylene torch1 and1 on account of the fact that the heat can be applied exactly where it is required and in the amount required1 the arc can in almost all cases supply welding heat for less cost than a forge fire or heating furnace4 ,the one great advantage of the oxy-acetylene method in comparison with other methods of welding is the fact that in some cases of very thin sheet1 the weld can be made somewhat sooner than is possible otherwise4 ,with metal of #ah gauge or thicker1 this advantage is eliminated4 ,in cutting steel1 the oxy-acetylene torch is superior to almost any other possible method4 ,arc ,welding ,machines4--,a consideration of the function and purpose of the various types of arc welding machines shows that the only reason for the use of any machine is either for conversion of the current from alternating to direct1 or1 if the current is already direct1 then the saving in the application of this current in the arc4 ,it is practically out of the question to apply an alternating current arc to welding for the reason that in any arc practically all the heat is liberated at the positive electrode1 which means that1 in alternating current1 half the heat is liberated at each electrode as the current changes its direction of flow or alternates4 ,another disadvantage of the alternating arc is that it is difficult of control and application4 ,in all arc welding by the use of the carbon arc1 the positive electrode is made the piece to be welded1 while in welding with metallic electrodes this may be either the piece to be welded of the rod that is used as a filler4 ,the voltage across the arc is a variable quantity1 depending on the length of the flame1 its temperature and the gases liberated in the arc4 ,with a carbon electrode the voltage will vary from zero to forty-five volts4 ,with the metallic electrode the voltage will vary from zero to thirty volts4 ,it is1 therefore1 necessary for the welding machine to be able to furnish to the arc the requisite amount of current1 this amount being varied1 and furnish it at all times at the voltage required4 ,the simplest welding apparatus is a resistance in series with the arc4 ,this is entirely satisfactory in every way except in cost of current4 ,by the use of resistance in series with the arc and using #bbj volts as the supply1 from eighty to ninety per cent of the current is lost in heat at the resistance4 ,another disadvantage is the fact that most materials change their resistance as their temperature changes1 thus making the amount of current for the arc a variable quantity1 depending on the temperature of the resistance4 ,there have been various methods originated for saving the power mentioned and a good many machines have been put on the market for this purpose4 ,all of them save some power over what a plain resistance would use4 ,practically all arc welding machines at the present time are motor generator sets1 the motor of which is arranged for the supply voltage and current1 this motor being direct connected to a compound wound generator delivering approximately seventy-five volts direct current4 ,then by the use of a resistance1 this seventy-five volt supply is applied to the arc4 ,since the voltage across the arc will vary from zero to fifty volts1 this machine will save from zero up to seventy per cent of the power that the machine delivers4 ,the rest of the power1 of course1 has to be dissipated in the resistance used in series with the arc4 ,a motor generator set which can be purchased from any electrical company1 with a long piece of fence wire wound around a piece of asbestos1 gives results equally as good and at a very small part of the first cost4 ,it is possible to construct a machine which will eliminate all losses in the resistance2 in other words1 eliminate all resistance in series with the arc4 ,a machine of this kind will save its cost within a very short time1 providing the welder is used to any extent4 ,putting it in figures1 the results are as follows for average conditions4 ,current at #b;c per kilowatt hour1 metallic electrode arc of #aej amperes1 carbon arc #ejj amperes2 voltage across the metallic electrode arc #bj1 voltage across the carbon arc #ce4 ,supply current #bbj volts1 direct4 ,in the case of the metallic electrode1 if resistance is used1 the cost of running this arc is sixty-six cents per hour4 ,with the carbon electrode1 #b4bj per hour4 ,if a motor generator set with a seventy volt constant potential machine is used for a welder1 the cost will be as follows3 ,metallic electrode #be4b;c4 ,carbon electrode #hd;c per hour4 ,with a machine which will deliver the required voltage at the arc and eliminate all the resistance in series with the arc1 the cost will be as follows3 ,metallic electrode #g4b;c per hour2 carbon electrode #db;c per hour4 ,this is with the understanding that the arc is held constant and continuously at its full value4 ,this1 however1 is practically impossible and the actual load factor is approximately fifty per cent1 which would mean that operating a welder as it is usually operated1 this result will be reduced to one-half of that stated in all cases4 ,,chapter ,,vii ,,hand ,,forging ,,and ,,welding ,smithing1 or blacksmithing1 is the process of working heated iron1 steel or other metals by forging1 bending or welding them4 ,the ,forge4--,the metal is heated in a forge consisting of a shallow pan for holding the fire1 in the center of which is an opening from below through which air is forced to make a hot fire4 ,illustration3 ,figure #dh4--,tuyere ,construction on a ,forge ,air is forced through this hole1 called a tuyere 7,figure #dh7 by means of a hand bellows1 a rotary fan operated with crank or lever1 or with a fan driven from an electric motor4 ,the harder the air is driven into the fire above the tuyere the more oxygen is furnished and the hotter the fire becomes4 ,directly below the tuyere is an opening through which the ashes that drop from the fire may be cleaned out4 ,the ,fire4--,the fire is made by placing a small piece of waste soaked in oil1 kerosene or gasoline1 over the tuyere1 lighting the waste1 then starting the fan or blower slowly4 ,gradually cover the waste1 while it is burning brightly1 with a layer of soft coal4 ,the coal will catch fire and burn after the waste has been consumed4 ,a piece of waste half the size of a person's hand is ample for this purpose4 ,the fuel should be smithing coal4 ,a lump of smithing coal breaks easily1 shows clean and even on all sides and should not break into layers4 ,the coal is broken into fine pieces and wet before being used on the fire4 ,the fire should be kept deep enough so that there is always three or four inches of fire below the piece of metal to be heated and there should be enough fire above the work so that no part of the metal being heated comes in contact with the air4 ,the fire should be kept as small as possible while following these rules as to depth4 ,to make the fire larger1 loosen the coal around the edges4 ,to make the fire smaller1 pack wet coal around the edges in a compact mass and loosen the fire in the center4 ,add fresh coal only around the edges of the fire4 ,it will turn to coke and can then be raked onto the fire4 ,blow only enough air into the fire to keep it burning brightly1 not so much that the fire is blown up through the top of the coal pack4 ,to prevent the fire from going out between jobs1 stick a piece of soft wood into it and cover with fresh wet coal4 ,tools4--,the hammer is a ball pene1 or blacksmith's hammer1 weighing about a pound and a half4 ,the sledge is a heavy hammer1 weighing from #e to #bj pounds and having a handle #cj to #cf inches long4 ,the anvil is a heavy piece of wrought iron 7,figure #di71 faced with steel and having four legs4 ,it has a pointed horn on one end1 an overhanging tail on the other end and a flat top4 ,in the tail there is a square hole called the hardie hole and a round one called the spud hole4 ,illustration3 ,figure #di4--;,anvil1 ,showing ,horn1 ,tail1 ,hardie ,hole and ,spud ,hole ,tongs1 with handles about one foot long and jaws suitable for holding the work1 are used4 ,to secure a firm grip on the work1 the jaws may be heated red hot and hammered into shape over the piece to be held1 thus giving a properly formed jaw4 ,jaws should touch the work along their entire length4 ,the set hammer is a hammer1 one end of whose head is square and flat1 and from this face the head tapers evenly to the other face4 ,the large face is about #a-a_/d inches square4 ,the flatter is a hammer having one face of its head flat and about #b-a_/b inches square4 ,swages are hammers having specially formed faces for finishing rounds1 squares1 hexagons1 ovals1 tapers1 etc4 ,fullers are hammers having a rounded face1 long in one direction4 ,they are used for spreading metal in one direction only4 ,the hardy is a form of chisel with a short1 square shank which may be set into the hardie hole for cutting off hot bars4 ,operations4--,blacksmithing consists of bending1 drawing or upsetting with the various hammers1 or in punching holes4 ,bending is done over the square corners of the anvil if square cornered bends are desired1 or over the horn of the anvil if rounding bends1 eyes1 hooks1 etc41 are wanted4 ,to bend a ring or eye in the end of a bar1 first figure the length of stock needed by multiplying the diameter of the hole by #ca_/g1 then heat the piece to a good full red at a point this distance back from the end4 ,next bend the iron over at a #ij degree angle 7square7 at this point4 ,next1 heat the iron from the bend just made clear to the point and make the eye by laying the part that was bent square over the horn of the anvil and bending the extreme tip into part of a circle4 ,keep pushing the piece farther and farther over the horn of the anvil1 bending it as you go4 ,do not hammer directly over the horn of the anvil1 but on the side where you are doing the bending4 ,to make the outside of a bend square1 sharp and full1 rather than slightly rounding1 the bent piece must be laid edgewise on the face of the anvil4 ,that is1 after making the bend over the corner of the anvil1 lay the piece on top of the anvil so that its edge and not the flat side rests on the anvil top4 ,with the work in this position1 strike directly against the corner with the hammer so that the blows come in line1 first with one leg of the work1 then the other1 and always directly on the corner of the piece4 ,this operation cannot be performed by laying the work so that one leg hangs over the anvil's corner4 ,to make a shoulder on a rod or bar1 heat the work and lay flat across the top of the anvil with the point at which the shoulder is desired at the edge of the anvil4 ,then place the set hammer on top of the piece1 with the outside edge of the set hammer directly over the edge of the anvil4 ,while hammering in this position keep the work turning continually4 ,to draw stock means to make it longer and thinner by hammering4 ,a piece to be drawn out is usually laid across the horn of the anvil while being struck with the hammer4 ,the metal is then spread in only one direction in place of being spread in every direction1 as it would be if laid on the anvil face4 ,to draw the work1 heat it to as high a temperature as it will stand without throwing sparks and burning4 ,the fuller may be used for drawing metal in place of laying the work over the horn of the anvil4 ,when drawing round stock1 it should be first drawn out square1 and when almost down to size it may be rounded4 ,when pointing stock1 the same rule of first drawing out square applies4 ,upsetting means to make a piece shorter in length and greater in thickness or width1 or both shorter and thicker4 ,to upset short pieces1 heat to a bright red at the place to be upset1 then stand on end on the anvil face and hammer directly down on top until of the right form4 ,longer pieces may be swung against the anvil or placed upright on a heavy piece of metal lying on the floor or that is sunk into the floor4 ,while standing on this heavy piece the metal may be upset by striking down on the end with a heavy hammer or the sledge4 ,if a bend appears while upsetting1 it should be straightened by hammering back into shape on the anvil face4 ,light blows affect the metal for only a short distance from the point of striking1 but heavy blows tend to swell the metal more equally through its entire length4 ,in driving rivets that should fill the holes1 heavy blows should be struck1 but to shape the end of a rivet or to make a head on a rod1 light blows should be used4 ,the part of the piece that is heated most will upset the most4 ,to punch a hole through metal1 use a tool steel punch with its end slightly tapering to a size a little smaller than the hole to be punched4 ,the end of the punch must be square across and never pointed or rounded4 ,first drive the punch part way through from one side and then turn the work over4 ,when you turn it over1 notice where the bulge appears and in that way locate the hole and drive the punch through from the second side4 ,this makes a cleaner and more even hole than to drive completely through from one side4 ,when the punch is driven in from the second side1 the place to be punched through should be laid over the spud hole in the tail of the anvil and the piece driven out of the work4 ,work when hot is larger than it will be after cooling4 ,this must be remembered when fitting parts or trouble will result4 ,a two-foot bar of steel will be #a_/d inch longer when red hot than when cold4 ,the temperatures of iron correspond to the following colors3 ,dullest red seen in the dark444 #hgh ,dullest red seen in daylight444 #hhg ,dull red44444444444444444444444 #aajj ,full red44444444444444444444444 #acgj ,light red4444444444444444444444 #aeej ,orange4444444444444444444444444 #afej ,light orange4444444444444444444 #agbe ,yellow4444444444444444444444444 #ahbe ,light yellow4444444444444444444 #aiej ,bending ,pipes and ,tubes4--,it is difficult to make bends or curves in pipes and tubing without leaving a noticeable bulge at some point of the work4 ,seamless steel tubing may be handled without very great danger of this trouble if care is used1 but iron pipe1 having a seam running lengthwise1 must be given special attention to avoid opening the seam4 ,bends may be made without kinking if the tube or pipe is brought to a full red heat all the way around its circumference and at the place where the bend is desired4 ,hold the cool portion solidly in a vise and1 by taking hold of the free end1 bend very slowly and with a steady pull4 ,the pipe must be kept at full red heat with the flames from one or more torches and must not be hammered to produce the bend4 ,if a sufficient purchase cannot be secured on the free end by the hand1 insert a piece of rod or a smaller pipe into the opening4 ,while making the bend1 should small bulges appear1 they may be hammered back into shape before proceeding with the work4 ,tubing or pipes may be bent while being held between two flat metal surfaces while at a bright red heat4 ,the metal plates at each side of the work prevent bulging4 ,another method by which tubing may be bent consists of filling completely with tightly packed sand and fitting a solid cap or plug at each end4 ,thin brass tubing may be filled with melted resin and may be bent after the resin cools4 ,to remove the resin it is necessary to heat the tube1 allowing it to run out4 ,large jobs of bending should be handled in special pipe bending machines in which the work is forced through formed rolls which prevent its bulging4 ,,welding ,welding with the heat of a blacksmith forge fire1 or a coal or illuminating gas fire1 can only be performed with iron and steel because of the low heat which is not localized as with the oxy-acetylene and electric processes4 ,iron to be welded in this manner is heated until it reaches the temperature indicated by an orange color1 not white1 as is often stated1 this orange color being slightly above #cfjj degrees ,fahrenheit4 ,steel is usually welded at a bright red heat because of the danger of oxidizing or burning the metal if the temperature is carried above this point4 ,the ,fire4--,if made in a forge1 the fire should be built from good smithing coal or1 better still1 from coke4 ,gas fires are1 of course1 produced by suitable burners and require no special preparation except adjustment of the heat to the proper degree for the size and thickness of the metal being welded so that it will not be burned4 ,a coal fire used for ordinary forging operations should not be used for welding because of the impurities it contains4 ,a fresh fire should be built with a rather deep bed of coal1 four to eight inches being about right for work ordinarily met with4 ,the fire should be kept burning until the coal around the edges has been thoroughly coked and a sufficient quantity of fuel should be on and around the fire so that no fresh coal will have to be added while working4 ,after the coking process has progressed sufficiently1 the edges should be packed down and the fire made as small as possible while still surrounding the ends to be joined4 ,the fire should not be altered by poking it while the metal is being heated4 ,the best form of fire to use is one having rather high banks of coked coal on each side of the mass1 leaving an opening or channel from end to end4 ,this will allow the added fuel to be brought down on top of the fire with a small amount of disturbance4 ,preparing to ,weld4--,if the operator is not familiar with the metal to be handled1 it is best to secure a test piece if at all possible and try heating it and joining the ends4 ,various grades of iron and steel call for different methods of handling and for different degrees of heat1 the proper method and temperature being determined best by actual test under the hammer4 ,the form of the pieces also has a great deal to do with their handling1 especially in the case of a more or less inexperienced workman4 ,if the pieces are at all irregular in shape1 the motions should be gone through with before the metal is heated and the best positions on the anvil as well as in the fire determined with regard to the convenience of the workman and speed of handling the work after being brought to a welding temperature4 ,unnatural positions at the anvil should be avoided as good work is most difficult of performance under these conditions4 ,scarfing4--,while there are many forms of welds1 depending on the relative shape of the pieces to be joined1 the portions that are to meet and form one piece are always shaped in the same general way1 this shape being called a scarf4 ,the end of a piece of work1 when scarfed1 is tapered off on one side so that the extremity comes to a rather sharp edge4 ,the other side of the piece is left flat and a continuation in the same straight plane with its side of the whole piece of work4 ,the end is then in the form of a bevel or mitre joint 7,figure #ej74 ,illustration3 ,figure #ej4--,scarfing ,ends of ,work ,ready for ,welding ,scarfing may be produced in any one of several ways4 ,the usual method is to bring the ends to a forging heat1 at which time they are upset to give a larger body of metal at the ends to be joined4 ,this body of metal is then hammered down to the taper on one side1 the length of the tapered portion being about one and a half times the thickness of the whole piece being handled4 ,each piece should be given this shape before proceeding farther4 ,the scarf may be produced by filing1 sawing or chiseling the ends1 although this is not good practice because it is then impossible to give the desired upset and additional metal for the weld4 ,this added thickness is called for by the fact that the metal burns away to a certain extent or turns to scale1 which is removed before welding4 ,when the two ends have been given this shape they should not fit as closely together as might be expected1 but should touch only at the center of the area to be joined 7,figure #ea74 ,that is to say1 the surface of the beveled portion should bulge in the middle or should be convex in shape so that the edges are separated by a little distance when the pieces are laid together with the bevels toward each other4 ,this is done so that the scale which is formed on the metal by the heat of the fire can have a chance to escape from the interior of the weld as the two parts are forced together4 ,illustration3 ,figure #ea4--,proper ,shape of ,scarfed ,ends ,if the scarf were to be formed with one or more of the edges touching each other at the same time or before the centers did so1 the scale would be imprisoned within the body of the weld and would cause the finished work to be weak1 while possibly giving a satisfactory appearance from the outside4 ,fluxes4--,in order to assist in removing the scale and other impurities and to make the welding surfaces as clean as possible while being joined1 various fluxing materials are used as in other methods of welding4 ,for welding iron1 a flux of white sand is usually used1 this material being placed on the metal after it has been brought to a red heat in the fire4 ,steel is welded with dry borax powder1 this flux being applied at the same time as the iron flux just mentioned4 ,borax may also be used for iron welding and a mixture of borax with steel borings may also be used for either class of work4 ,mixtures of sal ammoniac with borax have been successfully used1 the proportions being about four parts of borax to one of sal ammoniac4 ,various prepared fluxing powders are on the market for this work1 practically all of them producing satisfactory results4 ,after the metal has been in the fire long enough to reach a red heat1 it is removed temporarily and1 if small enough in size1 the ends are dipped into a box of flux4 ,if the pieces are large1 they may simply be pulled to the edge of the fire and the flux then sprinkled on the portions to be joined4 ,a greater quantity of flux is required in forge welding than in electric or oxy-acetylene processes because of the losses in the fire4 ,after the powder has been applied to the surfaces1 the work is returned to the fire and heated to the welding temperature4 ,heating the ,work4--,after being scarfed1 the two pieces to be welded are placed in the fire and brought to the correct temperature4 ,this temperature can only be recognized by experiment and experience4 ,the metal must be just below that point at which small sparks begin to be thrown out of the fire and naturally this is a hard point to distinguish4 ,at the welding heat the metal is almost ready to flow and is about the consistency of putty4 ,against the background of the fire and coal the color appears to be a cream or very light yellow and the work feels soft as it is handled4 ,it is absolutely necessary that both parts be heated uniformly and so that they reach the welding temperature at the same time4 ,for this reason they should be as close together in the fire as possible and side by side4 ,when removed to be hammered together1 time is saved if they are picked up in such a way that when laid together naturally the beveled surfaces come together4 ,this makes it necessary that the workman remember whether the scarfed side is up or down1 and to assist in this it is a good thing to mark the scarfed side with chalk or in some other noticeable manner1 so that no mistake will be made in the hurry of placing the work on the anvil4 ,the common practice in heating allows the temperature to rise until the small white sparks are seen to come from the fire4 ,any heating above this point will surely result in burning that will ruin the iron or steel being handled4 ,the best welding heat can be discerned by the appearance of the metal and its color after experience has been gained with this particular material4 ,test welds can be made and then broken1 if possible1 so that the strength gained through different degrees of heat can be known before attempting more important work4 ,welding4--,when the work has reached the welding temperature after having been replaced in the fire with the flux applied1 the two parts are quickly tapped to remove the loose scale from their surfaces4 ,they are then immediately laid across the top of the anvil1 being placed in a diagonal position if both pieces are straight4 ,the lower piece is rested on the anvil first with the scarf turned up and ready to receive the top piece in the position desired4 ,the second piece must be laid in exactly the position it is to finally occupy because the two parts will stick together as soon as they touch and they cannot well be moved after having once been allowed to come in contact with each other4 ,this part of the work must be done without any unnecessary loss of time because the comparatively low heat at which the parts weld allows them to cool below the working temperature in a few seconds4 ,the greatest difficulty will be experienced in withdrawing the metal from the fire before it becomes burned and in getting it joined before it cools below this critical point4 ,the beveled edges of the scarf are1 of course1 the first parts to cool and the weld must be made before they reach a point at which they will not join1 or else the work will be defective in appearance and in fact4 ,if the parts being handled are of such a shape that there is danger of bending a portion back of the weld1 this part may be cooled by quickly dipping it into water before laying the work on the anvil to be joined4 ,the workman uses a heavy hand hammer in making the joint1 and his helper1 if one is employed1 uses a sledge4 ,with the two parts of the work in place on the anvil1 the workman strikes several light blows1 the first ones being at a point directly over the center of the weld1 so that the joint will start from this point and be worked toward the edges4 ,after the pieces have united the helper strikes alternate blows with his sledge1 always striking in exactly the same place as the last stroke of the workman4 ,the hammer blows are carried nearer and nearer to the edges of the weld and are made steadily heavier as the work progresses4 ,the aim during the first part of the operation should be to make a perfect joint1 with every part of the surfaces united1 and too much attention should not be paid to appearance1 at least not enough to take any chance with the strength of the work4 ,it will be found1 after completion of the weld1 that there has been a loss in length equal to one-half the thickness of the metal being welded4 ,this loss is occasioned by the burned metal and the scale which has been formed4 ,finishing the ,weld4--,if it is possible to do so1 the material should be hammered into the shape that it should remain with the same heat that was used for welding4 ,it will usually be found1 however1 that the metal has cooled below the point at which it can be worked to advantage4 ,it should then be replaced in the fire and brought back to a forging heat4 ,illustration3 ,figure #eb4--,upsetting and ,scarfing the ,end of a ,rod ,while shaping the work at this forging heat every part that has been at a red heat should be hammered with uniformly light and even blows as it cools4 ,this restores the grain and strength of the iron or steel to a great extent and makes the unavoidable weakness as small as possible4 ,forms of ,welds4--,the simplest of all welds is that called a lap weld4 ,this is made between the ends of two pieces of equal size and similar form by scarfing them as described and then laying one on top of the other while they are hammered together4 ,a butt weld 7,figure #eb7 is made between the ends of two pieces of shaft or other bar shapes by upsetting the ends so that they have a considerable flare and shaping the face of the end so that it is slightly higher in the center than around the edges1 this being done to make the centers come together first4 ,the pieces are heated and pushed into contact1 after which the hammering is done as with any other weld4 ,illustration3 ,figure #ec4--,scarfing for a ,t ,weld ,a form similar to the butt weld in some ways is used for joining the end of a bar to a flat surface and is called a jump weld4 ,the bar is shaped in the same way as for a butt weld4 ,the flat plate may be left as it is1 but if possible a depression should be made at the point where the shaft is to be placed4 ,with the two parts heated as usual1 the bar is dropped into position and hammered from above4 ,as soon as the center of the weld has been made perfect1 the joint may be finished with a fuller driven all the way around the edge of the joint4 ,when it is required to join a bar to another bar or to the edge of any piece at right angles the work is called a ,t weld from its shape when complete 7,figure #ec74 ,the end of the bar is scarfed as described and the point of the other bar or piece where the weld is to be made is hammered so that it tapers to a thin edge like one-half of a circular depression4 ,the pieces are then laid together and hammered as for a lap weld4 ,the ends of heavy bar shapes are often joined with a ,v1 or cleft1 weld4 ,one bar end is shaped so that it is tapering on both sides and comes to a broad edge like the end of a chisel4 ,the other bar is heated to a forging temperature and then slit open in a lengthwise direction so that the ,v-shaped opening which is formed will just receive the pointed edge of the first piece4 ,with the work at welding heat1 the two parts are driven together by hammering on the rear ends and the hammering then continues as with a lap weld1 except that the work is turned over to complete both sides of the joint4 ,illustration3 ,figure #ed4-,splitting ,ends to ,be ,welded in ,thin ,work ,the forms so far described all require that the pieces be laid together in the proper position after removal from the fire1 and this always causes a slight loss of time and a consequent lowering of the temperature4 ,with very light stock1 this fall of temperature would be so rapid that the weld would be unsuccessful1 and in this case the lock weld is resorted to4 ,the ends of the two pieces to be joined are split for some distance back1 and one-half of each end is bent up and the other half down 7,figure #ed74 ,the two are then pushed together and placed in the fire in this position4 ,when the welding heat is reached1 it is only necessary to take the work out of the fire and hammer the parts together1 inasmuch as they are already in the correct position4 ,other forms of welds in which the parts are too small to retain their heat1 can be made by first riveting them together or cutting them so that they can be temporarily fastened in any convenient way when first placed in the fire4 ,,chapter ,,viii ,,soldering1 ,,brazing ,,and ,,thermit ,,welding ,,soldering ,common solder is an alloy of one-half lead with one-half tin1 and is called half and half4 ,hard solder is made with two-thirds tin and one-third lead4 ,these alloys1 when heated1 are used to join surfaces of the same or dissimilar metals such as copper1 brass1 lead1 galvanized iron1 zinc1 tinned plate1 etc4 ,these metals are easily joined1 but the action of solder with iron1 steel and aluminum is not so satisfactory and requires greater care and skill4 ,the solder is caused to make a perfect union with the surfaces treated with the help of heat from a soldering iron4 ,the soldering iron is made from a piece of copper1 pointed at one end and with the other end attached to an iron rod and wooden handle4 ,a flux is used to remove impurities from the joint and allow the solder to secure a firm union with the metal surface4 ,the iron1 and in many cases the work1 is heated with a gasoline blow torch1 a small gas furnace1 an electric heater or an acetylene and air torch4 ,the gasoline torch which is most commonly used should be filled two-thirds full of gasoline through the hole in the bottom1 which is closed by a screw plug4 ,after working the small hand pump for #aj to #bj strokes1 hold the palm of your hand over the end of the large iron tube on top of the torch and open the gasoline needle valve about a half turn4 ,hold the torch so that the liquid runs down into the cup below the tube and fills it4 ,shut the gasoline needle valve1 wipe the hands dry1 and set fire to the fuel in the cup4 ,just as the gasoline fire goes out1 open the gasoline needle valve about a half turn and hold a lighted match at the end of the iron tube to ignite the mixture of vaporized gasoline and air4 ,open or close the needle valve to secure a flame about #d inches long4 ,on top of the iron tube from which the flame issues there is a rest for supporting the soldering iron with the copper part in the flame4 ,place the iron in the flame and allow it to remain until the copper becomes very hot1 not quite red1 but almost so4 ,a new soldering iron or one that has been misused will have to be tinned before using4 ,to do this1 take the iron from the fire while very hot and rub the tip on some flux or dip it into soldering acid4 ,then rub the tip of the iron on a stick of solder or rub the solder on the iron4 ,if the solder melts off the stick without coating the end of the iron1 allow a few drops to fall on a piece of tin plate1 then nil the end of the iron on the tin plate with considerable force4 ,alternately rub the iron on the solder and dip into flux until the tip has a coating of bright solder for about half an inch from the end4 ,if the iron is in very bad shape1 it may be necessary to scrape or file the end before dipping in the flux for the first time4 ,after the end of the iron is tinned in this way1 replace it on the rest of the torch so that the tinned point is not directly in the flame1 turning the flame down to accomplish this4 ,flux4--,the commonest flux1 which is called soldering acid1 is made by placing pieces of zinc in muriatic 7hydrochloric7 acid contained in a heavy glass or porcelain dish4 ,there will be bubbles and considerable heat evolved and zinc should be added until this action ceases and the zinc remains in the liquid1 which is now chloride of zinc4 ,this soldering acid may be used on any metal to be soldered by applying with a brush or swab4 ,for electrical work1 this acid should be made neutral by the addition of one part ammonia and one part water to each three parts of the acid4 ,this neutralized flux will not corrode metal as will the ordinary acid4 ,powdered resin makes a good flux for lead1 tin plate1 galvanized iron and aluminum4 ,tallow1 olive oil1 beeswax and vaseline are also used for this purpose4 ,muriatic acid may be used for zinc or galvanized iron without the addition of the zinc1 as described in making zinc chloride4 ,the addition of two heaping teaspoonfuls of sal ammoniac to each pint of the chloride of zinc is sometimes found to improve its action4 ,soldering ,metal ,parts4--,all surfaces to be joined should be fitted to each other as accurately as possible and then thoroughly cleaned with a file1 emery cloth1 scratch bush or by dipping in lye4 ,work may be cleaned by dipping it into nitric acid which has been diluted with an equal volume of water4 ,the work should be heated as hot as possible without danger of melting1 as this causes the solder to flow better and secure a much better hold on the surfaces4 ,hard solder gives better results than half and half1 but is more difficult to work4 ,it is very important that the soldering iron be kept at a high heat during all work1 otherwise the solder will only stick to the surfaces and will not join with them4 ,sweating is a form of soldering in which the surfaces of the work are first covered with a thin layer of solder by rubbing them with the hot iron after it has been dipped in or touched to the soldering stick4 ,these surfaces are then placed in contact and heated to a point at which the solder melts and unites4 ,sweating is much to be preferred to ordinary soldering where the form of the work permits it4 ,this is the only method which should ever be used when a fitting is to be placed over the end of a length of tube4 ,soldering ,holes4--,clean the surfaces for some distance around the hole until they are bright1 and apply flux while holding the hot iron near the hole4 ,touch the tip of the iron to some solder until the solder is picked up on the iron1 and then place this solder1 which was just picked up1 around the edge of the hole4 ,it will leave the soldering iron and stick to the metal4 ,keep adding solder in this way until the hole has been closed up by working from the edges and building toward the center4 ,after the hole is closed1 apply more flux to the job and smooth over with the hot iron until there are no rough spots4 ,should the solder refuse to flow smoothly1 the iron is not hot enough4 ,soldering ,seams4--,clean back from the seam or split for at least half an inch all around and then build up the solder in the same way as was done with the hole4 ,after closing the opening1 apply more flux to the work and run the hot iron lengthwise to smooth the job4 ,soldering ,wires4--,clean all insulation from the ends to be soldered and scrape the ends bright4 ,lay the ends parallel to each other and1 starting at the middle of the cleaned portion1 wrap the ends around each other1 one being wrapped to the right1 the other to the left4 ,hold the hot iron under the twisted joint and apply flux to the wire4 ,then dip the iron in the solder and apply to the twisted portion until the spaces between the wires are filled with solder4 ,finish by smoothing the joint and cleaning away all excess metal by rubbing the hot iron lengthwise4 ,the joint should now be covered with a layer of rubber tape and this covered with a layer of ordinary friction tape4 ,steel and ,iron4--,steel surfaces should be cleaned1 then covered with clear muriatic acid4 ,while the acid is on the metal1 rub with a stick of zinc and then tin the surfaces with the hot iron as directed4 ,cast iron should be cleaned and dipped in strong lye to remove grease4 ,wash the lye away with clean water and cover with muriatic acid as with steel4 ,then rub with a piece of zinc and tin the surfaces by using resin as a flux4 ,it is very difficult to solder aluminum with ordinary solder4 ,a special aluminum solder should be secured1 which is easily applied and makes a strong joint4 ,zinc or phosphor tin may be used in place of ordinary solder to tin the surfaces or to fill small holes or cracks4 ,the aluminum must be thoroughly heated before attempting to solder and the flux may be either resin or soldering acid4 ,the aluminum must be thoroughly cleaned with dilute nitric acid and kept hot while the solder is applied by forcible rubbing with the hot iron4 ,,brazing ,this is a process for joining metal parts1 very similar to soldering1 except that brass is used to make the joint in place of the lead and zinc alloys which form solder4 ,brazing must not be attempted on metals whose melting point is less than that of sheet brass4 ,two pieces of brass to be brazed together are heated to a temperature at which the brass used in the process will melt and flow between the surfaces4 ,the brass amalgamates with the surfaces and makes a very strong and perfect joint1 which is far superior to any form of soldering where the work allows this process to be used1 and in many cases is the equal of welding for the particular field in which it applies4 ,brazing ,heat and ,tools4--,the metal commonly used for brazing will melt at heats between #acej and #afej ,fahrenheit4 ,to bring the parts to this temperature1 various methods are in use1 using solid1 liquid or gaseous fuels4 ,while brazing may be accomplished with the fire of the blacksmith forge1 this method is seldom satisfactory because of the difficulty of making a sufficiently clean fire with smithing coal1 and it should not be used when anything else is available4 ,large jobs of brazing may be handled with a charcoal fire built in the forge1 as this fuel produces a very satisfactory and clean fire4 ,the only objection is in the difficulty of confining the heat to the desired parts of the work4 ,the most satisfactory fire is that from a fuel gas torch built for this work4 ,these torches are simply forms of ,bunsen burners1 mixing the proper quantity of air with the gas to bring about a perfect combustion4 ,hose lines lead to the mixing tube of the gas torch1 one line carrying the gas and the other air under a moderate pressure4 ,the air line is often dispensed with1 allowing the gas to draw air into the burner on the injector principle1 much the same as with illuminating gas burners for use with incandescent mantles4 ,valves are provided with which the operator may regulate the amount of both gas and air1 and ordinarily the quality and intensity of the flame4 ,when gas is not available1 recourse may be had to the gasoline torch made for brazing4 ,this torch is built in the same way as the small portable gasoline torches for soldering operations1 with the exception that two regulating needle valves are incorporated in place of only one4 ,the torches are carried on a framework1 which also supports the work being handled4 ,fuel is forced to the torch from a large tank of gasoline into which air pressure is pumped by hand4 ,the torches are regulated to give the desired flame by means of the needle valves in much the same way as with any other form of pressure torch using liquid fuel4 ,another very satisfactory form of torch for brazing is the acetylene-air combination described in the chapter on welding instruments4 ,this torch gives the correct degree of heat and may be regulated to give a clean and easily controlled flame4 ,regardless of the source of heat1 the fire or flame must be adjusted so that no soot is deposited on the metal surfaces of the work4 ,this can only be accomplished by supplying the exact amounts of gas and air that will produce a complete burning of the fuel4 ,with the brazing torches in common use two heads are furnished1 being supplied from the same source of fuel1 but with separate regulating devices4 ,the torches are adjustably mounted in such a way that the flames may be directed toward each other1 heating two sides of the work at the same time and allowing the pieces to be completely surrounded with the flame4 ,except for the source of heat1 but one tool is required for ordinary brazing operations1 this being a spatula formed by flattening one end of a quarter-inch steel rod4 ,the spatula is used for placing the brazing metal on the work and for handling the flux that is required in this work as in all other similar operations4 ,spelter4--,the metal that is melted into the joint is called spelter4 ,while this name originally applied to but one particular grade or composition of metal1 common use has extended the meaning until it is generally applied to all grades4 ,spelter is variously composed of alloys containing copper1 zinc1 tin and antimony1 the mixture employed depending on the work to be done4 ,the different grades are of varying hardness1 the harder kinds melting at higher temperatures than the soft ones and producing a stronger joint when used4 ,the reason for not using hard spelter in all cases is the increased difficulty of working it and the fact that its melting point is so near to some of the metals brazed that there is great danger of melting the work as well as the spelter4 ,the hardest grade of spelter is made from three-fourths copper with one-fourth zinc and is used for working on malleable and cast iron and for steel4 ,this hard spelter melts at about #afej and is correspondingly difficult to handle4 ,a spelter suitable for working with copper is made from equal parts of copper and zinc1 melting at about #adjj ,fahrenheit1 #ejj below the melting point of the copper itself4 ,a still softer brazing metal is composed of half copper1 three-eighths zinc and one-eighth tin4 ,this grade is used for fastening brass to iron and copper and for working with large pieces of brass to brass4 ,for brazing thin sheet brass and light brass castings1 a metal is used which contains two-thirds tin and one-third antimony4 ,the low melting point of this last composition makes it very easy to work with and the danger of melting the work is very slight4 ,however1 as might be expected1 a comparatively weak joint is secured1 which will not stand any great strain4 ,all of the above brazing metals are used in powder form so that they may be applied with the spatula where the joint is exposed on the outside of the work4 ,in case it is necessary to braze on the inside of a tube or any deep recess1 the spelter may be placed on a flat rod long enough to reach to the farthest point4 ,by distributing the spelter at the proper points along the rod it may be placed at the right points by turning the rod over after inserting into the recess4 ,flux4--,in order to remove the oxides produced under brazing heat and to allow the brazing metal to flow freely into place1 a flux of some kind must be used4 ,the commonest flux is simply a pure calcined borax powder1 that is1 a borax powder that has been heated until practically all the water has been driven off4 ,calcined borax may also be mixed with about #ae per cent of sal ammoniac to make a satisfactory fluxing powder4 ,it is absolutely necessary to use flux of some kind and a part of whatever is used should be made into a paste with water so that it can be applied to the joint to be brazed before heating4 ,the remainder of the powder should be kept dry for use during the operation and after the heat has been applied4 ,preparing the ,work4--,the surfaces to be brazed are first thoroughly cleaned with files1 emery cloth or sand paper4 ,if the work is greasy1 it should be dipped into a bath of lye or hot soda water so that all trace of oil is removed4 ,the parts are then placed in the relation to each other that they are to occupy when the work has been completed4 ,the edges to be joined should make a secure and tight fit1 and should match each other at all points so that the smallest possible space is left between them4 ,this fit should not be so tight that it is necessary to force the work into place1 neither should it be loose enough to allow any considerable space between the surfaces4 ,the molten spelter will penetrate between surfaces that water will flow between when the work and spelter have both been brought to the proper heat4 ,it is1 of course1 necessary that the two parts have a sufficient number of points of contact so that they will remain in the proper relative position4 ,the work is placed on the surface of the brazing table in such a position that the flame from the torches will strike the parts to be heated1 and with the joint in such a position that the melted spelter will flow down through it and fill every possible part of the space between the surfaces under the action of gravity4 ,that means that the edge of the joint must be uppermost and the crack to be filled must not lie horizontal1 but at the greatest slant possible4 ,better than any degree of slant would be to have the line of the joint vertical4 ,the work is braced up or clamped in the proper position before commencing to braze1 and it is best to place fire brick in such positions that it will be impossible for cooling draughts of air to reach the heated metal should the flame be removed temporarily during the process4 ,in case there is a large body of iron1 steel or copper to be handled1 it is often advisable to place charcoal around the work1 igniting this with the flame of the torch before starting to braze so that the metal will be maintained at the correct heat without depending entirely on the torch4 ,when handling brass pieces having thin sections there is danger of melting the brass and causing it to flow away from under the flame1 with the result that the work is ruined4 ,if1 in the judgment of the workman1 this may happen with the particular job in hand1 it is well to build up a mould of fire clay back of the thin parts or preferably back of the whole piece1 so that the metal will have the necessary support4 ,this mould may be made by mixing the fire clay into a stiff paste with water and then packing it against the piece to be supported tightly enough so that the form will be retained even if the metal softens4 ,brazing4--,with the work in place1 it should be well covered with the paste of flux and water1 then heated until this flux boils up and runs over the surfaces4 ,spelter is then placed in such a position that it will run into the joint and the heat is continued or increased until the spelter melts and flows in between the two surfaces4 ,the flame should surround the work during the heating so that outside air is excluded as far as is possible to prevent excessive oxidization4 ,when handling brass or copper1 the flame should not be directed so that its center strikes the metal squarely1 but so that it glances from one side or the other4 ,directing the flame straight against the work is often the cause of melting the pieces before the operation is completed4 ,when brazing two different metals1 the flame should play only on the one that melts at the higher temperature1 the lower melting part receiving its heat from the other4 ,this avoids the danger of melting one before the other reaches the brazing point4 ,the heat should be continued only long enough to cause the spelter to flow into place and no longer4 ,prolonged heating of any metal can do nothing but oxidize and weaken it1 and this practice should be avoided as much as possible4 ,if the spelter melts into small globules in place of flowing1 it may be caused to spread and run into the joint by lightly tapping the work4 ,more dry flux may be added with the spatula if the tapping does not produce the desired result4 ,excessive use of flux1 especially toward the end of the work1 will result in a very hard surface on all the work1 a surface which will be extremely difficult to finish properly4 ,this trouble will be present to a certain extent anyway1 but it may be lessened by a vigorous scraping with a wire brush just as soon as the work is removed from the fire4 ,if allowed to cool before cleaning1 the final appearance will not be as good as with the surplus metal and scale removed immediately upon completing the job4 ,after the work has been cleaned with the brush it may be allowed to cool and finished to the desired shape1 size and surface by filing and polishing4 ,when filed1 a very thin line of brass should appear where the crack was at the beginning of the work4 ,if it is desired to avoid a square shoulder and fill in an angle joint to make it rounding1 the filling is best accomplished by winding a coil of very thin brass wire around the part of the work that projects and then causing this to flow itself or else allow the spelter to fill the spaces between the layers of wire4 ,copper wire may also be used for this purpose1 the spaces being filled with melted spelter4 ,,thermit ,,welding ,the process of welding which makes use of the great heat produced by oxygen combining with aluminum is known as the ,thermit process and was perfected by ,dr4 ,hans ,goldschmidt4 ,the process1 which is controlled by the ,goldschmidt ,thermit ,company1 makes use of a mixture of finely powdered aluminum with an oxide of iron called by the trade name1 ,thermit4 ,the reaction is started with a special ignition powder1 such as barium superoxide and aluminum1 and the oxygen from the iron oxide combining with the aluminum1 producing a mass of superheated steel at about #ejjj degrees ,fahrenheit4 ,after the reaction1 which takes from4 #cj seconds to a minute1 the molten metal is drawn from the crucible on to the surfaces to be joined4 ,its extreme heat fuses the metal and a perfect joint is the result4 ,this process is suited for welding iron or steel parts of comparatively large size4 ,preparation4--,the parts to be joined are thoroughly cleaned on the surfaces and for several inches back from the joint1 after which they are supported in place4 ,the surfaces between which the metal will flow are separated from #a_/d to #a inch1 depending on the size of the parts1 but cutting or drilling part of the metal away4 ,after this separation is made for allowing the entrance of new metal1 the effects of contraction of the molten steel are cared for by preheating adjacent parts or by forcing the ends apart with wedges and jacks4 ,the amount of this last separation must be determined by the shape and proportions of the parts in the same way as would be done for any other class of welding which heats the parts to a melting point4 ,yellow wax1 which has been warmed until plastic1 is then placed around the joint to form a collar1 the wax completely filling the space between the ends and being provided with vent holes by imbedding a piece of stout cord1 which is pulled out after the wax cools4 ,a retaining mould 7,figure #ee7 made from sheet steel or fire brick is then placed around the parts4 ,this mould is then filled with a mixture of one part fire clay1 one part ground fire brick and one part fire sand4 ,these materials are well mixed and moistened with enough water so that they will pack4 ,this mixture is then placed in the mould1 filling the space between the walls and the wax1 and is packed hard with a rammer so that the material forms a wall several inches thick between any point of the mould and the wax4 ,the mixture must be placed in the mould in small quantities and packed tight as the filling progresses4 ,illustration3 ,figure #ee4--,thermit ,mould ,construction ,three or more openings are provided through this moulding material by the insertion of wood or pipe forms4 ,one of these openings will lead from the lowest point of the wax pattern and is used for the introduction of the preheating flame4 ,another opening leads from the top of the mould into this preheating gate1 opening into the preheating gate at a point about one inch from the wax pattern4 ,openings1 called risers1 are then provided from each of the high points of the wax pattern to the top of the mould1 these risers ending at the top in a shallow basin4 ,the molten metal comes up into these risers and cares for contraction of the casting1 as well as avoiding defects in the collar of the weld4 ,after the moulding material is well packed1 these gate patterns are tapped lightly and withdrawn1 except in the case of the metal pipes which are placed at points at which it would be impossible to withdraw a pattern4 ,preheating4--,the ends to be welded are brought to a bright red heat by introducing the flame from a torch through the preheating gate4 ,the torch must use either gasoline or kerosene1 and not crude oil1 as the crude oil deposits too much carbon on the parts4 ,preheating of other adjacent parts to care for contraction is done at this time by an additional torch burner4 ,the heating flame is started gently at first and gradually increased4 ,the wax will melt and may be allowed to run out of the preheating gate by removing the flame at intervals for a few seconds4 ,the heat is continued until the mould is thoroughly dried and the parts to be joined are brought to the red heat required4 ,this leaves a mould just the shape of the wax pattern4 ,the heating gate should then be plugged with a sand core1 iron plug or piece of fitted fire brick1 and backed up with several shovels full of the moulding mixture1 well packed4 ,illustration3 ,figure #ef4--,thermit ,crucible ,plug4 ,a1 ,hard burn magnesia stone2 ,b1 ,magnesia thimble2 ,c1 ,refractory sand2 ,d1 ,metal disc2 ,e1 ,asbestos washer2 ,f1 ,tapping pin ,thermit ,metal4--,the reaction takes place in a special crucible lined with magnesia tar1 which is baked at a red heat until the tar is driven off and the magnesia left4 ,this lining should last from twelve to fifteen reactions4 ,this magnesia lining ends at the bottom of the crucible in a ring of magnesia stone and this ring carries a magnesia thimble through which the molten steel passes on its way to the mould4 ,it will usually be necessary to renew this thimble after each reaction4 ,this lower opening is closed before filling the crucible with thermit by means of a small disc or iron carrying a stem1 which is called a tapping pin 7,figure #ef74 ,this pin1 ,f1 is placed in the thimble with the stem extending down through the opening and exposing about two inches4 ,the top of this pin is covered with an asbestos1 washer1 ,e1 then with another iron disc4 ,d1 and finally with a layer of refractory sand4 ,the crucible is tapped by knocking the stem of the pin upwards with a spade or piece of flat iron about four feet long4 ,the charge of thermit is added by placing a few handfuls over the refractory sand and then pouring in the balance required4 ,the amount of thermit required is calculated from the wax used4 ,the wax is weighed before and after filling the entire space that the thermit will occupy4 ,this does not mean only the wax collar1 but the space of the mould with all gates filled with wax4 ,the number of pounds of wax required for this filling multiplied by #be will give the number of pounds of thermit to be used4 ,to this quantity of thermit should be added ,i per cent of pure manganese1 #a per cent nickel thermit and #ae per cent of steel punchings4 ,it is necessary1 when more than #aj pounds of thermit will be used1 to mix steel punchings not exceeding #c_/h inch diameter by #a_/h inch thick with the powder in order to sufficiently retard the intensity of the reaction4 ,half a teaspoonful of ignition powder is placed on top of the thermit charge and ignited with a storm match or piece of red hot iron4 ,the cover should be immediately closed on the top of the crucible and the operator should get away to a safe distance because of the metal that may be thrown out of the crucible4 ,after allowing about #cj seconds to a minute for the reaction to take place and the slag to rise to the top of the crucible1 the tapping pin is struck from below and the molten metal allowed to run into the mould4 ,the mould should be allowed to remain in place as long as possible1 preferably over night1 so as to anneal the steel in the weld1 but in no case should it be disturbed for several hours after pouring4 ,after removing the mould1 drill through the metal left in the riser and gates and knock these sections off4 ,no part of the collar should be removed unless absolutely necessary4 ,,chapter ,,ix ,,oxygen ,,process ,,for ,,removal ,,of ,,carbon ,until recently the methods used for removing carbon deposits from gas engine cylinders were very impractical and unsatisfactory4 ,the job meant dismantling the motor1 tearing out all parts1 and scraping the pistons and cylinder walls by hand4 ,the work was never done thoroughly4 ,it required hours of time to do it1 and then there was always the danger of injuring the inside of the cylinders4 ,these methods have been to a large extent superseded by the use of oxygen under pressure4 ,the various devices that are being manufactured are known as carbon removers1 decarbonizers1 etc41 and large numbers of them are in use in the automobile and gasoline traction motor industry4 ,outfit4--,the oxygen carbon cleaner consists of a high pressure oxygen cylinder with automatic reducing valve1 usually constructed on the diaphragm principle1 thus assuring positive regulation of pressure4 ,this valve is fitted with a pressure gauge1 rubber hose1 decarbonizing torch with shut off and flexible tube for insertion into the chamber from which the carbon is to be removed4 ,there should also be an asbestos swab for swabbing out the inside of the cylinder or other chamber with kerosene previous to starting the operation4 ,the action consists in simply burning the carbon to a fine dust in the presence of the stream of oxygen1 this dust being then blown out4 ,operation4--,the following are instructions for operating the cleaner3-- 7#a7 ,close valve in gasoline supply line and start the motor1 letting it run until the gasoline is exhausted4 7#b7 ,if the cylinders be ,t or ,l head1 remove either the inlet or the exhaust valve cap1 or a spark plug if the cap is tight4 ,if the cylinders have overhead valves1 remove a spark plug4 ,if any spark plug is then remaining in the cylinder it should be removed and an old one or an iron pipe plug substituted4 7#c7 ,raise the piston of the cylinder first to be cleaned to the top of the compression stroke and continue this from cylinder to cylinder as the work progresses4 7#d7 ,in motors where carbon has been burned hard1 the cylinder interior should then be swabbed with kerosene before proceeding4 ,work the swab1 saturated with kerosene1 around the inside of the cylinder until all the carbon has been moistened with the oil4 ,this same swab may be used to ignite the gas in the cylinder in place of using a match or taper4 7#e7 ,make all connections to the oxygen cylinder4 7#f7 ,insert the torch nozzle in the cylinder1 open the torch valve gradually and regulate to about two lbs4 pressure4 ,manipulate the nozzle inside the cylinder and light a match or other flame at the opening so that the carbon starts to burn4 ,cover the various points within the cylinder and when there is no further burning the carbon has been removed4 ,the regulating and oxygen tank valves are operated in exactly the same way as for welding as previously explained4 ,it should be carefully noted that when the piston is up1 ready to start the operation1 both valves must be closed4 ,there will be a considerable display of sparks while this operation is taking place1 but they will not set fire to the grease and oil4 ,care should be used to see that no gasoline is about4 ,,index ,acetylene filtering generators in tanks piping properties of purification of ,acetylene-air torches ,air oxygen from ,alloys table of ,alloy steel ,aluminum alloys welding ,annealing ,anvil ,arc welding1 electric machines ,asbestos1 use of1 in welding ,babbitt ,bending pipes and tubes ,bessemer steel ,beveling ,brass welding ,brazing electric heat and tools spelter ,bronze welding ,butt welding ,calcium carbide ,carbide storage of1 ,fire ,underwriters' ,rules to water generator ,carbon removal by oxygen process ,case hardening steel ,cast iron welding ,champfering ,charging generator ,chlorate of potash oxygen ,conductivity of metals ,copper alloys welding ,crucible steel ,cutting1 oxy-acetylene torches ,dissolved acetylene ,electric arc welding ,electric welding troubles and remedies ,expansion of metals ,flame1 welding ,fluxes for brazing for soldering ,forge fire practice tools tuvere construction of welding welding preparation welds1 forms of ,forging ,gas holders ,gases1 heating power of ,generator1 acetylene carbide to water construction ,generator location of operation and care of overheating requirements water to carbide ,german silver ,gloves ,goggles ,hand forging ,hardening steel ,heat treatment of steel ,hildebrandt process ,hose ,injectors1 adjuster ,iron cast grades of malleable cast wrought ,jump weld ,lap welding ,lead ,linde process ,liquid air oxygen ,magnalium ,malleable iron welding ,melting points of metals ,metal alloys1 table of ,metals characteristics of conductivity of expansion of heat treatment of melting points of tensile strength of weight of ,nickel ,nozzle sizes1 torch ,open hearth steel ,oxy-acetylene cutting welding practice ,oxygen cylinders weight of ,pipes1 bending ,platinum ,preheating ,removal of carbon by oxygen process ,resistance method of electric welding ,restoration of steel ,rods1 welding ,safety devices ,scarfing ,solder ,soldering flux holes seams steel and iron wires ,spelter ,spot welding ,steel alloys ,bessemer crucible heat treatment of open hearth restoration of tensile strength of welding ,strength of metals ,tank valves ,tapering ,tables of welding information ,tempering steel ,thermit metal preheating preparation welding ,tin ,torch acetylene-air care construction cutting high pressure low pressure medium pressure nozzles practice ,valves1 regulating tank ,water to carbide generator ,welding aluminum brass bronze butt cast iron copper electric electric arc flame forge information and tables instruments lap malleable iron materials practice1 oxy-acetylene rods spot steel table thermit torches various metals wrought iron ,wrought iron welding ,zinc