,,transcriber',s ,,note ,italic text is denoted by underscores4 ,bold text is denoted by equal signs4 ,some minor changes to the text are noted at the end of the book4 ,elementary ,lathe ,practice ,,as ,,adapted ,,to ,,the ,,teaching ,,of ,,machine ,,shop ,,practice ,,in ,,technical ,,schools4 ,,by ,t4 ,j4 ,,palmateer ,,instructor ,,in ,,machine ,,work ,leland ,stanford ,junior ,university ,copyright #aiag1 by ,t4 ,j4 ,palmateer ,,first ,,edition #aiag ,press of ,nolte ,bros4 ,illustration3 ,union ,mark ,san ,jose1 ,california ,,preface ,the object of this instruction book is to help beginners to acquire some familiarity with the more common lathe operations in the shortest practicable period of time4 ,for this purpose three exercises have been designed with the view of giving the student the maximum amount of information in the small amount of time usually allowed for this purpose4 ,the repetition of operations has therefore been avoided wherever it was considered advisable and the time lost in simply cutting off metal has been reduced as much as possible4 ,it is assumed that beginners will receive oral instruction on the manipulation of the lathe1 as in shifting the belt1 the feed control1 etc4 ,it will also be necessary for the instructor to give a practical demonstration of most of the operations4 ,the lathe speeds for the different operations as indicated in this book are only approximately correct since the actual cutting speed of the tool in feet per minute varies with the size and kind of lathe used4 ,the instructor is expected to designate the proper speeds although the belt connections given herein will generally be close enough for beginners4 ,in case it is considered advisable to devote to the elementary lathe operations less time than would be necessary to complete the three exercises presented herein1 very good results can be obtained if the student will read all of the instructions carefully and then do only ,exercise ,no4 #a and piece ,b of ,exercise ,no4 #c4 ,the instructions here given are not intended as fixed rules for it is recognized that some of the operations may be done by other methods with equally good results4 ,t4 ,j4 ,,palmateer4 ,stanford ,university1 ,cal4 ,january #aiag4 ,,exercise ,no4 #a4 ,,fit ,,shaft ,,to ,,collar--,,running ,,fit ,illustration ,cut off with a power hack-saw a piece of steel #f inches long from a bar #a inch in diameter4 ,this will allow of an inch for finishing the ends and of an inch for turning the diameter4 ,an experienced lathe operator would use a piece of steel of an inch in diameter1 but for beginners it is better to use larger stock to allow for practice turning4 ,,centering ,center both ends in the centering machine4 ,the size of the center in this shaft should be from to of an inch in diameter4 ,larger work should have deeper centers4 ,illustration3 ,fig4 #a ,illustration3 ,fig4 #b ,illustration3 ,fig4 #c ,illustration3 ,fig4 #d ,if a centering machine is not available1 the work may be centered by first locating the center with a pair of dividers and center punch and then using a combination drill and countersink in the lathe as shown in ,fig4 #a4 ,in this case the work is held by hand to prevent it from turning4 ,as this work is to be turned1 it is necessary to center it only approximately true4 ,accurate ,centering4--,when the work is to be centered accurately1 it may be done by putting one end in the lathe chuck and the other in a steady rest4 ,a pointed tool is then used in the tool post as shown in ,fig4 #b4 ,the point of this tool has an angle of #fj degrees1 the same as the lathe centers1 and is ground like a flat drill so that it cuts on both sides4 ,after the shaft is centered with this tool1 a center hole about of an inch in diameter should be drilled4 ,this is done by holding the drill in the tail-stock of the lathe with a drill-chuck1 as shown in ,fig4 #c4 ,the object of this center hole is to give the center of the shaft a bearing on the lathe center a short distance back from the point1 as at ,a in ,fig4 #d4 ,,placing ,,work ,,in ,,lathe ,the work is made to rotate on the lathe centers by fastening a lathe dog to the shaft at the head-stock end1 as shown at ,a in ,fig4 #e4 ,illustration3 ,fig4 #e ,the tail-stock center is adjusted so that the shaft will rotate freely1 yet be tight enough to allow no slack1 or lost motion4 ,since the shaft rotates on this center1 it should be kept well lubricated by using machine oil1 or a mixture of graphite and oil4 ,to get the best results in turning this sort of work1 it is necessary to face both ends before turning and to rough turn the whole piece to within about #j4jc1 or #j4jd of an inch of the finished size before any part of it is finished4 ,however1 it is not always necessary to do this4 ,the object of first rough turning the shaft all over is to remove the internal strains of the steel and to wear the centers down to a good bearing before any finishing cuts are taken4 ,the purpose of facing the ends is to get them square1 or true1 and smooth4 ,,finishing ,,end ,,of ,,shaft ,to face the ends1 use a regular turning tool starting to cut from the outside and feeding by hand towards the center with the cross feed4 ,such a tool will leave a ridge near the center1 as shown in ,fig4 #f4 ,this ridge is cut off with a sharp pointed1 side cutting tool1 as shown in ,fig4 #g1 which is also used for taking the finishing cut across the whole end of the bar4 ,when taking this finishing cut1 lard oil1 or some other lubricant1 should be used4 ,illustration3 ,fig4 #f ,illustration3 ,fig4 #g ,after the finishing cut has been taken1 any small ridge1 or fin that remains at the edge of the center is removed by slightly changing the angle of the tool in the tool post and allowing about of an inch play between the centers4 ,having the work loose like this when the lathe is running1 allows the extreme point of the side tool to extend beyond the edge of the center and cut a smooth end4 ,the lathe should run slow for the finishing cut and fast when the regular turning tool is used4 ,,turning ,,the ,,shaft ,the first1 or roughing cut1 is taken with a high-speed steel tool1 or bit1 fastened in a tool holder4 ,the tool holder is clamped in the tool post of the lathe so that the point of the tool is at1 or a little above1 the center1 or axis1 of the lathe1 as in ,fig4 #h4 ,if the point of the bit is too high1 it is easy to see that1 as the shaft rotates1 the tool will not cut at all1 ,fig4 #i4 ,in case the tool is set below the center1 the cutting action is very poor so that turning tools are never set as in ,fig4 #aj4 ,illustration3 ,fig4 #h ,illustration3 ,fig4 #i ,illustration3 ,fig4 #aj ,illustration3 ,fig4 #aa ,speed of the ,lathe4--,in taking the heavy roughing cuts1 the belt may be placed on the second largest step of the cone1 while for the finishing cuts the lathe should run a little faster1 say with the belt in the next smaller step4 ,grinding ,turning ,tool4--,the front1 or point1 and the sides of the tool are ground at an angle1 which is called the clearance4 ,if the tool has too little clearance1 it will not cut freely1 while if it has too much clearance1 the point will be so thin that it will break off or become dull quickly4 ,the top of the tool is also ground at an angle4 ,this is called the rake4 ,if the tool has too little rake1 it will not cut freely and if it has too much1 the edge will soon break down4 ,it requires some practice for a beginner to learn the proper rake and clearance that should be given to a tool4 ,fig4 #aa shows a tool ground with clearance and rake that will give very good results4 ,direction ,tool ,should ,travel4--,the depth of the first cut should be about of an inch and the travel of the tool should always be from the tail-stock end towards the head-stock4 ,if the travel is in the opposite direction1 the pressure on the tail-stock center is increased1 causing it to heat quickly4 ,the length of the cut should be as great as possible without the lathe dog striking the tool1 or cross-rest4 ,adjusting the ,lathe to ,turn ,straight4--,after the first cut1 the work should be calipered and if it is not the same diameter at both ends the tail-stock should be adjusted so that the lathe will turn straight4 ,the tail-stock adjustment is made by loosening the main clamping nut ,b and one of the screws ,c and then tightening the other screw ,c on the opposite side of the tail-stock1 ,fig4 #e4 ,if the shaft is larger at the tail-stock end1 the tail-stock should be moved towards the front of the lathe one half the difference between the diameters of the shaft at the two ends4 ,in doing close work1 the tail-stock should be adjusted as closely as possible1 but in this case if it is off center only a little1 say #j4jjb or #j4jjc of an inch1 it will be close enough providing it is set so that the shaft will be turned larger at the head-stock end4 ,if the tail-stock is set so that the shaft is turned larger at the tail-stock end1 the shaft will be too small at the other end after the finishing cut is taken4 ,fitting ,shaft to the ,collar4--,after the roughing cut is taken and the lathe has been adjusted so that it turns approximately straight1 the end of the shaft is turned for about of an inch so that it will just fit the hole in the collar1 shown in the drawing of ,exercise #a4 ,to measure this3 first set the inside calipers to the diameter of the hole in the collar1 then set the outside calipers to the inside calipers and caliper the shaft as accurately as possible4 ,for a final test of this diameter1 remove the work from the lathe and try it with the collar itself4 ,the advantage of turning but of an inch at the end of the shaft is this2 if the finishing cut were set too deep1 only of an inch of the shaft would be too small1 while if this cut were taken the whole length1 the entire shaft would be too small4 ,after the shaft has been turned at the end so that it fits the collar1 the rest of the shaft should be turned a little larger1 say #j4jjb or #j4jjc of an inch1 in diameter4 ,this will leave enough to finish with a file4 ,filing4--,the object of filing is to take out the tool marks1 but it is also found to be much easier to make a close fit by filing off the last #j4jjb or #j4jjc of an inch than to take so small a cut with a tool4 ,the amount of allowance for filing depends upon the character of the finishing cut4 ,since the less filing required the better1 the finishing cut should be made as smooth as possible4 ,the tool used for the roughing cut may also be used for finishing1 but it is usually necessary to re-sharpen it4 ,after it is reset in the tool post1 the point should be flattened a little wider than the pitch of the feed1 say about of an inch1 and parallel with the work4 ,this is done with an oilstone4 ,for filing work on a lathe1 a single cut file is used4 ,this is called a lathe1 or mill file4 ,the stroke of the file should be slow1 steady1 and straight across the shaft4 ,the lathe should run a little faster for filing than for turning1 the object being to have the work make several revolutions for a single stroke of the file4 ,if the lathe runs too slow and the stroke of the file is too fast1 the shaft1 instead of being filed round1 will have a series of flat places on the surface4 ,after the work is finished as close to the dog as possible1 reverse it in the lathe and finish that part where the dog was fastened4 ,,exercise ,no4 #b4 ,illustration ,the finished shaft in ,exercise ,no4 #a may be used for ,exercise ,no4 #b4 ,place the shaft in the bench vise and with a rule and scriber lay off the dimensions3 #a in41 #c in41 and #a in4 ,then center punch the lines just deep enough so that they can be easily seen when the work is in the lathe4 ,turn the large end first4 ,when it is necessary to turn a fixed distance1 or to a line as in this case1 it is well to disconnect the feed when the tool is within about of an inch from the end of the cut and to feed the tool the rest of the distance by hand4 ,if this is not done1 the tool may travel farther than it is intended to4 ,it is better to turn the portions to be threaded a little under rather than over size4 ,for if they are over size1 the threads will not fit the standard size nut1 but if under size the threads do not need to be cut so deep in order to fit the nut4 ,for measuring the diameters of this piece set the calipers as accurately as possible by measuring from the end of the rule1 as shown in ,fig4 #ab4 ,illustration3 ,fig4 #ab ,illustration3 ,fig4 #ac ,cutting ,recess4--,the surface at the end as well as the recesses between the threads and the taper are cut with a square-nose1 or cutting-off tool1 ,fig4 #ac4 ,this tool should have a sharp smooth edge1 the point being set level with the center of the lathe4 ,to produce a smooth finished surface lard oil should be used with a slow feed and lathe speed4 ,after the end is turned to size1 reverse the work in the lathe and turn the other end and the taper before cutting the threads4 ,turning ,taper4--,the drawing calls for a taper of #a inch per foot4 ,this is cut by using a taper attachment1 or by setting the tail-stock off center4 ,as most lathes are not provided with a taper attachment1 the latter method will be used4 ,if the work was #ab inches long1 the tail-stock would be moved off center inch to turn a taper of #a inch per foot4 ,it being only #f inches long1 the tail-stock is set off center but half that amount1 or inch4 ,before taking the finishing cut1 caliper both ends to prove that the lathe is cutting the correct taper4 ,,thread ,,cutting ,the threads are cut to fit inch and inch nuts having ,united ,states ,standard threads4 ,these threads are flattened at the top and bottom to the amount of of the pitch instead of being sharp pointed as in the case of ,standard ,v-threads4 ,pitch4--,the pitch of the thread is the distance from the center of one thread to the center of the one adjoining4 ,on the end of the exercise having #ac threads per inch the pitch is of an inch so that the width of the flat at the top and bottom of this thread should be of of an inch1 or about 4#jji of an inch4 ,lead4--,the lead of the thread is the distance a nut on the screw will travel in making one complete turn4 ,for single threads the pitch and lead are the same1 but for double threads the lead is twice the pitch4 ,grinding ,tool4--,the sides of ,u4 ,s4 ,s4 threads form an angle of #fj degrees4 ,to cut this thread in a lathe1 a tool the same shape as the threads is used4 ,a gauge for grinding this tool accurately is shown in ,fig4 #ad4 ,illustration3 ,fig4 #ad ,illustration3 ,fig4 #ae ,illustration3 ,fig4 #af ,if a ,u4 ,s4 ,s4 thread gauge is not available1 the tool can be ground with the aid of a regular thread and center gauge1 shown in ,fig4 #ae4 ,with such a gauge the angle can be ground accurately1 but it will be necessary to measure the flat point with a rule4 ,the top of the tool should be ground so that it will be approximately in a horizontal plane when set in the lathe4 ,where the thread to be cut is as fine as #ac per inch the flat surface at the point of the tool is so small that the extreme point can be oil-stoned off instead of being taken off with the grinding wheel4 ,the flat point should never be wider than the standard size1 but if it is a little too narrow it will make very little difference in ordinary lathe work4 ,setting ,tool4--,to set the tool so that both sides of the thread will have the same angle1 the thread gauge is used as shown in ,fig4 #af4 ,the tool should be set on a level with the center of the lathe4 ,how ,lathe is ,geared4--,to cut #ac threads per inch the work must make #ac revolutions while the carriage1 which carries the tool1 travels one inch4 ,for this purpose the lathe spindle is connected to the lead screw with the proper size gears and the lead screw to the carriage by a split nut4 ,this split nut is back of the carriage apron and is opened and closed by the lever ,e1 ,fig4 #ag4 ,illustration3 ,fig4 #ag ,a4 ,index ,plate ,b4 ,stud ,gear ,c4 ,screw ,gear ,d4 ,intermediate or ,idle ,gear ,e4 ,lever for connecting ,carriage to ,lead ,screw ,j4 ,lever for ,disconnecting and ,reversing ,feed ,k4 ,adjustable ,stop for ,thread ,cutting ,illustration3 ,fig4 #ah ,if the lead screw of the lathe has #f threads per inch1 the gearing to cut #ac threads per inch must have the same ratio as #f is to #ac4 ,to cut #af threads the ratio would be #f to #af4 ,it is not necessary to figure the size of gears for the different threads as all lathes are provided with an index plate that designates the proper size gears to be placed on the stud ,b and screw ,c1 ,fig4 #ag1 for the desired thread4 ,to ,set ,change ,gear4--,to change these gears1 first loosen the nuts holding the stud and screw gears ,b and ,c4 ,next loosen the nut ,g4 ,this will allow the intermediate gear to drop away from the stud gear ,b4 ,then loosen the nut ,h so that the intermediate gear can be drawn back away from the gear on the lead screw ,c4 ,when the gears are put together1 they should be set so that there will be a little slack1 or lost motion1 between the different gears4 ,if they are set too close together1 they will make a great deal of noise when running and there is also danger of breaking the teeth4 ,while all lathes are not designed alike the method of changing the gears is very much the same on all machines except those having the quick change-gear device4 ,with a lathe having such a device1 instead of changing the gears on the stud and screw the same result is obtained by shifting a combination of levers4 ,why ,feed ,should ,be ,disconnected4--,the mechanism that controls the feed1 or travel1 of the tool when cutting threads is independent of that used for the feed when doing plain turning4 ,the two feeds usually run at different speeds so that if they are both in action at the same time the gears in the carriage will break4 ,for this reason all lathes are provided with some means of disconnecting the feed used for plain turning when cutting threads4 ,to disconnect the feed on the lathe shown in ,fig4 #ag1 move the lever ,j to the central1 or neutral1 position4 ,this should always be done before starting to cut the threads4 ,speed of ,lathe4--,the lathe should run slower for cutting threads than for plain turning4 ,with most lathes if the belt is on the largest step of the cone it will give about the right speed for cutting the threads in this exercise4 ,the object of running the lathe slow is to give the operator time to draw back the tool at the end of the cut and to obtain a smoother cut4 ,if the speed of the lathe is too fast1 the cutting action will be so quick that the tool1 instead of cutting clean and smooth1 will tear out the metal leaving a rough surface4 ,the slower the lathe runs the easier it is to cut the threads1 but it will also take longer to do the job4 ,it therefore requires practical experience to determine the proper speed to be used for cutting the different size threads4 ,chamfering4--,after the lathe and tool are properly set1 chamfer off the sharp corners where the threads begin and end with the side of the thread tool4 ,the depth of this cut should be about the same as that of the threads when finished4 ,if the corners are not chamfered1 the threads1 when cut1 will form a very thin edge1 or fin1 at the ends4 ,use of ,adjustable ,stop4--,to regulate the depth of each cut an adjustable stop is used as shown at ,k4 ,first move the tool so that the point just touches the work1 then adjust the screw on the attachment ,k so that the cross-rest will not go in any farther4 ,now move the carriage by hand until the point of the tool is a little past the tail-stock end of the work2 close the split nut on the lead screw with the lever ,e2 and turn the screw on the attachment ,k so that the tool can be moved in just enough to take a very light cut4 ,start the lathe and when the tool has reached the end of the cut back it out and reverse the lathe4 ,by reversing the lathe the tool is returned to the starting point without disconnecting any of the gearing4 ,the object of drawing the tool back is to prevent it from dragging on the work during its return4 ,the tool will never travel over the same path on the reverse as on the forward movement of the lathe on account of the slack1 or lost motion1 in the gears4 ,this first cut is taken to prove that the lathe is properly geared1 so the work should be measured with a rule1 or screw pitch gauge4 ,adjust the screw at ,k until the tool can be moved in deeper for the next cut and repeat the operation until the thread is nearly finished4 ,then the tool should be reset so that it will cut on only one side at a time4 ,finishing ,side of ,thread4--,when roughing out the threads1 the tool cuts on both sides of the point since it is fed straight into the work4 ,it is much easier1 though1 to finish the threads smooth if the tool cuts on one side only4 ,this is done by rapping the end of the tool holder so that it is turned in the tool post just enough to change the position of the point of the tool about 4#ja1 or 4#jb of an inch4 ,to prove that the tool is set over the proper amount1 turn the lathe forward by hand a few revolutions1 to take out all the slack1 or lost1 motion in the gears1 then move the tool into the groove of the thread until one side just touches the side of the thread4 ,the other side of the tool should then be about 4#ja1 or 4#jb of an inch away from the side of the thread4 ,after the tool is properly adjusted1 set the stop ,k4 ,the tool is then drawn back and the lathe reversed until the tool is at the end of the work ready for a cut4 ,it usually requires several finishing cuts to take out all the rough marks left by the roughing cuts4 ,when this side of the thread is finished1 the other side is finished in the same manner4 ,if the lathe is provided with a compound rest1 a somewhat different procedure is usually followed since the rest can be set at an angle of #cj degrees with the work1 as in ,fig4 #ah4 ,in this case the tool is moved in by turning the small hand-crank ,m until the side at ,o has been cut to the proper depth4 ,while making these first cuts1 the stop ,k is merely used to bring the cross-rest to the same position each time4 ,the tool is then drawn back slightly with the hand-crank ,m and the stop ,k adjusted so that the tool can be moved straight in by means of the hand-crank ,q4 ,this will finish the other side of the thread at ,p4 ,to determine when the thread is cut to the proper size the work is removed from the lathe and tested with a standard nut having ,u4 ,s4 ,s4 threads4 ,after the threads are cut on this end of the exercise1 it is reversed in the lathe and the other end threaded in a similar manner4 ,to prevent the screw of the dog from marring the portion already threaded two nuts should be screwed on and the dog fastened to the nuts4 ,how to ,reset the ,tool4--,when cutting threads of this size and larger1 the tool usually becomes dull from taking the heavy roughing cuts4 ,it is then necessary to resharpen it before taking the fine finishing cuts4 ,to reset the tool in the lathe first get the angles correct1 as shown in ,fig4 #af4 ,then revolve the lathe forward by hand to take up the slack in the gears and move the tool in close to the threads4 ,if the tool is in a position so that it will cut too much off one side of the thread1 it may be changed by disengaging the reversing gears with the lever ,r and turning the lathe by hand4 ,when the tool is in the proper position relative to the groove of the thread1 the reverse gear lever ,r is reset4 ,in a case where the tool is off the desired position only a very little1 it may be corrected by the rapping process4 ,if the lathe has a compound rest the tool may be brought to the correct position by turning the hand-crank ,m4 ,it would be well for beginners to practice thread cutting on a piece of scrap steel before trying to cut them on the exercise4 ,,exercise ,no4 #c4 ,,cast ,,iron ,,finished ,,all ,,over4 ,illustration ,sequence of ,operations3 #a4 ,finish the inside of ,piece ,a4 #b4 ,drill and ,ream the hole in ,piece ,b4 #c4 ,mount ,b on mandrel and finish outside4 #d4 ,screw ,a on ,b and finish the outside of ,a4 ,illustration3 ,piece ,a4 #aj ,thrds4 per #a ,u4 ,s4 ,s4 ,fig4 #ai ,rough ,casting ,illustration3 ,fig4 #bj ,finished ,casting ,,use ,,of #d-;,,jaw ,,chuck4 ,to machine the inside of piece ,a it is necessary to hold it in the lathe by means of an independent four-jaw chuck1 as shown in ,fig4 #ba4 ,work of this kind is usually chucked so that the outside surfaces will be within of an inch of running true4 ,illustration3 ,fig4 #ba ,the process of chucking the work is as follows3 ,centering ,work in the ,chuck4--,place the work in the chuck and adjust the jaws until they are all at approximately equal distances from the circles on the face of the chuck4 ,then put a cutting-off tool loosely in the tool post and move it close to the work and as near as possible to the end of the chuck jaws4 ,revolve the lathe by hand to prove if the work is centered4 ,if it is not centered to within of an inch1 readjust the jaws until it is4 ,now move the cutting-off tool to the end of the work and turn the lathe by hand4 ,if the end runs out of true1 rap it with a hammer at such points as will correct its position4 ,advantage of ,proper ,chucking4--,fig4 #ba shows the work held by the middle step of the cone4 ,one reason for holding it in this way is to permit the rough turning of the larger step while in the chuck4 ,if the work were held by the small end1 it would be apt to work loose when taking the heavy roughing cuts on account of the distance that the work projects out and the small diameter on which the chuck grips compared with that of the large end which is to be turned4 ,,rough ,,turning ,,and ,,boring4 ,after the work has been properly chucked1 rough turn the end and the largest diameter to within of an inch of the finished size4 ,all cast iron has a hard surface1 or scale1 from to of an inch deep so that it is necessary to run the lathe slower for the first cut than for those made after the scale has been removed4 ,in taking this first cut the tool should be set deep enough to permit the point to cut under the scale4 ,speed of ,lathe4--,the speed of the lathe in taking the roughing cut on work of this size should be about right if the belt is on the smallest step of the cone and the back gears are used4 ,after the scale is removed1 the lathe may be run faster4 ,a beginner will require experience before being able to determine the proper speeds and feeds for the different kinds of lathe work4 ,advantage of ,roughing ,inside4--,as the inside of piece ,a must fit the outside of the piece ,b1 the #a inch hole1 the threads1 and the taper must be machine true with each other1 or else ,a will not fit into ,b properly4 ,now if the taper should be finished and the work moved in the chuck before the threads and the #a inch hole are finished1 they would not be true with each other4 ,for this reason it would be well to rough bore the inside to within of an inch of the finished size before any of these three parts are finished4 ,roughing ,inside4--,to rough bore the taper use a regular turning tool4 ,set the compound rest to the correct angle and feed the tool in at that angle4 ,if the lathe is not provided with a compound rest1 the taper may be rough bored by turning both feeds by hand and following the cored surface as closely as possible4 ,the cored hole in the rough casting1 ,fig4 #ai1 is of an inch in diameter which allows of an inch for finishing the #a inch hole and for the portion where the threads are to be cut4 ,use of ,flat ,drill4--,to rough bore the hole a #a flat1 or lathe1 drill is used as shown in ,fig4 #ba4 ,the holder ,a is clamped in the tool post so that the slot in it will hold the drill at the center of the lathe4 ,if the drill is held above or below the center1 the hole will be drilled larger than the drill4 ,to prove that the slot in the holder is at the center1 move it close to the tail-stock center4 ,after the holder is properly set1 move it as close to the work as possible and feed the drill into the exercise by turning the hand-crank on the tail-stock4 ,this drill removes the hard surface1 or scale1 and also trues up1 or centers1 the hole to within 1 or of an inch4 ,now enlarge the portion of the hole where the threads are to be cut with a #a drill4 ,to determine when this drill has been fed in far enough1 mark on the drill with a piece of chalk the distance from the end of the work to the point where the recess is to be cut4 ,by sighting across the end of the work the operator can then see when the drill has been fed in the proper distance4 ,use of ,boring ,bar4--,to cut the square shoulder where the threads begin and the recess where they end1 use a tool and boring bar1 as shown in ,fig4 #bb1 held in the tool post4 ,the width of this tool is of an inch so that it will be necessary to take two cuts to make the recess wide enough4 ,such a narrow tool is used because it is less liable to chatter4 ,illustration3 ,fig4 #bb ,this tool is ground with clearance at the sides as well as at the front and it should also be noticed that it is wider at the cutting edge than back close to the boring bar4 ,this is done so that when the tool is fed into the work there will be little1 or no chance of its binding on the side4 ,to obtain the correct setting for the tool1 move the boring bar into the hole and bring it up close to one side4 ,the tool should then be adjusted until its cutting edge is parallel to the elements of this surface4 ,the work is now all roughed out so that it makes very little difference which of the three fitting parts is finished first4 ,,finishing ,,inside ,the #a inch hole has been drilled with a inch lathe drill1 but as such a tool cannot be relied upon to drill true to center1 or size1 it is necessary to turn it out with a boring tool4 ,with this tool the hole can be bored true to center and within 4#ja of an inch of the finished size4 ,the boring bar used in this case is the same as shown in ,fig4 #bb1 but the cutter has a rounded point and is similar to the tool used for outside turning except that it is ground with less clearance4 ,to insure accuracy and conserve time1 the hole is then finished with a shell reamer held in the lathe as shown in ,fig4 #bc4 ,illustration3 ,fig4 #bc ,reaming the ,hole4--,before starting the reamer1 the hole should be bored at the end1 for a distance of about of an inch1 to the size which will just permit the reamer to enter4 ,this diameter must be calipered very carefully and should be tested with the reamer itself4 ,the rest of the hole is then bored about 4#ja of an inch smaller in diameter to allow enough material for finishing with the reamer4 ,since the reamer used in this case cuts on the sides as well as on the end1 the hole must be bored true to center in order to be reamed true4 ,if the reamer has a tapered shank1 it is held in the lathe by a square shank socket and wrench1 as shown in ,fig4 #bc1 and is fed into the work by turning the hand-crank on the tail-stock4 ,illustration3 ,fig4 #bd ,in case the reamer has a straight shank1 it is held as shown in ,fig4 #bd4 ,here a dog is fastened to the end of the reamer and prevented from turning by a tool clamped at an angle in the tool post4 ,the end of the tool presses against the dog near the shank of the reamer so that as the reamer is fed into the work the carriage of the lathe is forced along with it4 ,this causes the tool to hold the end of the reamer against the center of the tail-stock4 ,when reaming work in a lathe1 if the tail-stock is off center the hole will be reamed too large at the front end4 ,accurate ,boring with ,boring ,bar4--,in turning out holes with a boring bar1 if all the cuts are started from one end1 that end will be bored larger than the other4 ,in case the hole is to be reamed1 the reamer will correct this1 but if the hole is to be finished with the boring bar it will be necessary to bore the hole from both ends4 ,this is done by reversing the feed of the carriage4 ,speed of ,lathe4--,the speed of the lathe for reaming should be slower than when using the boring bar4 ,if the belt is on the second smallest step of the cone with the back gears in1 the lathe should have about the right speed for reaming4 ,when using the boring bar1 the belt should be on the largest step of the cone without the back gear4 ,,inside ,,threading ,the inside threads are cut in very much the same manner as the outside ones4 ,the cutting tool is held in the boring bar and1 like all boring tools1 is ground with less clearance than tools used for outside work4 ,to regulate the depth of each cut1 the screw in the adjustable stop is placed between the stop and the cross-rest4 ,then by turning the screw in after a cut has been taken the cross-rest can be drawn back to permit a deeper cut with the tool4 ,cause of ,threads ,breaking4--,when cutting threads in cast iron1 they will break if the roughing cuts are too heavy and are liable to if they are cut to a sharp point4 ,another cause for the breaking of cast iron threads is the use of a dull tool1 or one with too little clearance4 ,finishing ,threads4--,as a general rule cast iron is machined without using a lubricant1 but in finishing threads a little lard oil will aid in producing a smooth finish4 ,,finishing ,,ends ,the end of the work may be finished by taking a very light cut with the turning tool and then scraping it with a lathe scraper1 as shown in ,fig4 #be4 ,to provide a rest for the scraper a tool is clamped in the tool post and as close as possible to the surface being scraped4 ,illustration3 ,fig4 #be ,illustration3 ,fig4 #bf ,a scraper is usually made from an old file ground smooth on the two sides and with a little clearance at the end4 ,,finishing ,,taper ,to finish the taper1 set the compound rest at an angle of #cj degrees with the axis of the lathe4 ,such a rest is normally at right angles with the lathe axis so that it must be turned through #fj degrees to cut the #cj degree angle4 ,a regular turning tool may be used to finish this angle1 but it should be set so that the straight side will be nearly parallel with the tapered surface4 ,if the lathe is not provided with a compound rest1 the angle may be cut with the side of a tool set at the proper angle4 ,to set this tool1 use the thread and center gauge1 as shown in ,fig4 #bf4 ,in case the angle is any other than #cj1 or #fj degrees1 it is necessary to set the tool with a bevel and bevel protractor4 ,after the taper has been cut1 it may be finished smooth by scraping with a lathe scraper in very much the same manner as shown in ,fig4 #be4 ,the tool that is used as a rest is set in as close as possible to the taper4 ,if this rest is too far away from the surface being finished1 the scraper will chatter leaving a rough surface4 ,illustration3 ,piece ,b4 #aj ,thrds4 per #a ,u4 ,s4 ,s4 ,rough ,casting ,fig4 #bg ,finished ,casting ,,drilling ,,and ,,reaming4 ,this piece is first placed in the chuck1 as shown in ,fig4 #bh1 and the end rough turned to see if it is a good casting4 ,the hole is then drilled with a inch twist drill and reamed out to size with a inch rose reamer4 ,illustration3 ,fig4 #bh ,centering ,twist ,drill4--,this drill will not bore a hole in the center unless the point is controlled in some way4 ,to do this1 a cutting-off tool is clamped in the tool post with its point well above the center of the lathe and is then moved close to the point of the drill4 ,as the drill starts to cut1 it wabbles a little on account of the point being off center4 ,the cutting-off tool is then gradually brought against the drill which is at the same time being slowly fed into the work by turning the hand-crank on the tail-stock4 ,it is necessary to have the drill centered true before it begins to cut the full diameter4 ,the drill should be placed in the tail-stock so that the cutting edges are vertical4 ,if they are horizontal1 it will be difficult to make the drill center4 ,if the hole in this piece were larger1 it would be cast with a core and then machined in the same manner as the #a inch hole in piece ,a1 but since it is cast solid1 the hole can be machined more advantageously by using a twist drill and a rose reamer4 ,reaming4--,after the hole has been drilled with the drill1 bore it out with a small boring tool for about of an inch from the end to the diameter that will just fit over the reamer and insure its starting true4 ,ream the hole with the reamer held in the same manner as the twist drill in ,fig4 #bh4 ,speed of ,lathe4--,the lathe should run slower for reaming than for drilling4 ,the speed will be about right for this size reamer if the belt is on the largest step of the cone without the back gears being used4 ,the speed for the drill may be much faster4 ,with a high-speed steel drill1 the belt can be run on the second smallest step of the cone4 ,if the drill is made of carbon steel1 a slower speed should be used4 ,advantage of ,rose ,reamer4--,in drilling long holes like this1 the drill is very apt to get off center a little as it is fed deeper into the work1 even though it may have been started dead true4 ,the reamer used in this case is called a rose reamer1 or rose bit1 and cuts on the end only4 ,for this reason1 if the hole is approximately true1 say within of an inch1 it will ream the hole straight and true to size if it is once started true4 ,,finishing ,,corner ,after the hole is bored and reamed1 the work may be finished at the end by using a tool ground like a threading tool1 but having an angle at the point a little less than #ij degrees1 as in ,fig4 #bi4 ,illustration3 ,fig4 #bi ,the boss1 or hub1 which is #a inches in diameter1 is finished with one cutting edge of this tool set nearly parallel to the work1 the point being a trifle deeper than the rest4 ,this will insure the full depth of cut for the entire length and also a good sharp corner4 ,the direction of feed for this tool should be from the end and towards the square corner or shoulder4 ,if it is fed in the opposite direction the tool is apt to chatter4 ,this tool is also used to finish the end1 but it is turned a little in the tool post so that the other cutting edge is nearly parallel to the surface to be cut4 ,after using this tool1 the work may be finished smoother by scraping the ends1 as in ,fig4 #be1 and by filing the boss1 or hub4 ,,use ,,of ,,mandrel1 ,,or ,,arbor ,before this piece can be finished on the outside1 it must be forced on a mandrel1 or arbor1 and placed in the lathe1 as shown in ,fig4 #cj4 ,most commercial shops are provided with hardened steel mandrels for this purpose1 but if one is not available it can be made from soft steel in the following manner3 ,illustration3 ,fig4 #cj ,making ,mandrel4--,cut off a piece of steel of suitable length1 say #f inches1 and rough turn it to within of an inch of the diameter of the hole4 ,then turn it at the end for a distance of about of an inch to the size that will just fit the hole4 ,the rest of the distance is now turned 4#jjb1 or 4#jjc of an inch larger and filed for about #c inches until it will just fit the hole4 ,the next #b inches are filed with a slight taper so that when the mandrel is pressed into the hole it will fit tight enough to hold the casting while it is being turned4 ,this kind of a fit is called a forced1 or driving fit4 ,when making such a mandrel1 it is not necessary to turn that portion to which the dog is fastened4 ,mounting ,work on ,mandrel4--,before pressing the mandrel in1 it should be oiled to prevent it from being marred1 or scored4 ,mandrels are usually forced in with a mandrel press1 but if one is not available1 they may be driven in with a hammer4 ,when this method is used1 a piece of lead1 or some other soft material1 must be held on the end of the mandrel to keep the hammer from marring the center4 ,,finishing ,,outside ,,of ,,piece ,b ,,to ,,fit ,a ,this casting is rough turned to within of an inch of the finished size before any part of it is finished4 ,the #a inch end is then turned until it fits the corresponding part of the hole in piece ,a as closely as possible and yet not so tight that it cannot be freely rotated4 ,this kind of a fit is called a close running fit4 ,cutting ,threads4--,the portion to be threaded should be turned a little smaller than the diameter at the bottom of the threads in piece ,a4 ,this size is measured by means of the inside spring-thread calipers4 ,there is no recess1 or groove1 cut at the end of this thread so that if the threading tool is allowed to travel farther than the end of the preceding cut1 either the point of the tool or the threads may break4 ,to prevent this1 the lathe is stopped when the tool is within a half a thread of the end and the cut finished by turning the lathe by hand4 ,in this way the lathe is kept under control and the tool may be drawn back when it reaches the end of the preceding cut4 ,experienced lathe operators do not1 as a rule1 turn the lathe by hand1 but control the lathe entirely by the shipper4 ,the speed of the lathe for cutting this thread will be about right for beginners if the belt is on the second smallest step of the cone and the back gears are thrown in4 ,finishing the ,angle1 or ,taper4--,the #cj degree angle may be cut by setting the compound rest to the correct angle and using a regular turning tool4 ,in case the tool leaves a few tool marks1 they may be removed by filing4 ,if the lathe is not provided with a compound rest1 this angle may be cut by setting a square-nose tool1 as in ,fig4 #ca1 with the aid of a thread gauge4 ,any other angle would have to be set with a bevel and bevel protractor4 ,illustration3 ,fig4 #ca ,this tool is not as wide as the surface to be cut because one that will cut the full width is very liable to chatter4 ,it is therefore better to make several cuts with a narrow tool4 ,the surface can then be finished smooth by filing4 ,the closeness of the fit of this taper with that in ,a can be tested by rubbing black paint1 which consists of lamp black and oil1 on the tapered surface in ,a4 ,when ,b is screwed into ,a1 marks will be made on ,b indicating the high spots4 ,if these are not too high1 they may be removed by filing4 ,,finishing ,,outside ,,of ,,piece ,a4 ,piece ,a may now be screwed on ,b and the outside rough turned to within of an inch of the finished size4 ,the ends of the different steps are finished to the proper length with the tool shown in ,fig4 #bi4 ,this same tool can then be used to turn the different diameters to within #j4jjb or #j4jjc of an inch of the required size4 ,these steps are brought to the final size by filing4 ,filing4--,the file for this work should be less than #a inch in width4 ,if it is wider than the steps1 a beginner will usually file the portion at the end of each step smaller in diameter than that which is close to the square corners4 ,the different diameters may be measured accurately with the micrometer calipers4 ,,knurling ,after piece ,a is finished1 it is removed from ,b and ,b is reversed in the lathe so that the boss may be knurled4 ,in case there is enough room between the dog and the work1 when held as in ,fig4 #cj1 there is no need to reverse the work for knurling since it can be done in this position4 ,the boss at the end of ,b is used as a handle so that if it were left smooth it would be hard to turn by hand4 ,the surface is therefore made rough with a knurling tool as shown in ,fig4 #cb4 ,illustration3 ,fig4 #cb ,the speed of the lathe should be about the same for knurling as for thread cutting4 ,if the lathe runs too fast1 the knurling tool does not cut satisfactorily4 ,the tool is set so that the face of the rollers is parallel with the surface to be knurled4 ,when starting the cut1 the rollers can be forced into the piece easier if about half of their width extends past the end of the work4 ,the knurling tool should be pressed into the work fast enough so that about one half the depth of the finished knurl will be cut while the lathe makes three or four revolutions4 ,if the tool is forced in too slow1 it will cut a finer knurled surface than the rollers are intended to cut4 ,the tool is fed along the surface in the same manner as in plain turning4 ,the speed at which the carriage of the lathe moves has no effect upon the pitch of the knurled surface since this is controlled by the pitch of the grooves in the rollers4 ,if a finer knurled surface is desired1 a knurling tool having rollers with finer grooves would have to be used4 ,,transcriber',s ,,note ,illustrations in this e,book have been positioned between paragraphs and outside quotations4 ,obvious typographical errors and punctuation errors have been corrected after careful comparison with other occurrences within the text and consultation of external sources4 ,some hyphens in words have been silently removed1 some added1 when a predominant preference was found in the original book4 ,except for those changes noted below1 all misspellings in the text1 and inconsistent or archaic usage1 have been retained4 ,pg #i3 #8straght' replaced with #8straight' ,pg #aa3 #8shoull' replaced with #8should' ,pg #ai3 #8diffrent' replaced with #8different4'