,transcriber's ,notes3 ,underscores 80 before and after a word or phrase indicate italics in the original text4 ,equal signs 80 before and after a word or phrase indicate bold in the original text4 ,small capitals have been converted to ,,solid capitals4 ,illustrations have been moved so they do not break up paragraphs4 ,typographical and punctuation errors have been silently corrected4 ,,machinery',s ,,reference ,,series ,,each ,,number ,,is ,,one ,,unit ,,in ,a ,,complete ,,library ,,of ,,machine ,,design ,,and ,,shop ,,practice ,,revised ,,and ,,republished ,,from ,,machinery ,,number #ace ,,precision ,,locating ,,and ,,dividing ,,methods ,,contents ,precision ,locating ,methods #c ,accurate ,dividing and ,spacing ,methods #ba ,locating ,work for ,boring on ,milling ,machine #cb ,copyright1 #aiad1 ,the ,industrial ,press1 ,publishers of ,,machinery1 #adj-adh ,lafayette ,street1 ,new ,york ,city ,other books in this series dealing with the subjects of ,toolmaking and kindred topics are as follows3 ,no4 #ca--,,thread ,,tools ,,and ,,gages ,no4 #fd--;,,gage ,,making ,,and ,,lapping ,no4 #ajg--;,,drop ,,forging ,,die ,,sinking ,no4 #acj--;,,gaging ,,tools ,,and ,,methods ,illustration3 ,,machinery ,,machinery ,the ,leading ,mechanical ,journal ,,machine ,,design ,,construction ,,shop ,,practice ,,the ,,industrial ,,press #adj-adh ,lafayette ,st4 ,new ,york ,city #ea-eb ,chancery ,lane1 ,london ,,chapter ,i ,,precision ,,locating ,,methods ,the degree of accuracy that is necessary in the construction of certain classes of machinery and tools1 has made it necessary for toolmakers and machinists to employ various methods and appliances for locating holes or finished surfaces to given dimensions and within the prescribed limits of accuracy4 ,in this treatise1 various approved methods of locating work1 such as are used more particularly in tool-rooms1 are described and illustrated4 ,these are not given1 in every case1 as being the best possible method under all conditions1 because1 as every mechanical man knows1 the best way may be dependent upon the element of accuracy with little regard for the time required to do the work1 or this order may be reversed2 therefore1 one method is seldom1 if ever1 the best under all circumstances1 and it is necessary for the workman to consider the conditions in each case and then be guided by his judgment and experience in determining just how the work should be done4 ,button ,method of ,accurately ,locating ,work ,among the different methods employed by toolmakers for accurately locating work such as jigs1 etc41 on the faceplate of a lathe1 one of the most commonly used is known as the 8button method40 ,this method is so named because cylindrical bushings or buttons are attached to the work in positions corresponding to the holes to be bored1 after which they are used in locating the work4 ,these buttons which are ordinarily about or inch in diameter1 are ground and lapped to the same size1 and the ends are finished perfectly square4 ,the outside diameter should preferably be such that the radius can easily be determined1 and the hole through the center should be about inch larger than the retaining screw so that the button can be adjusted laterally4 ,as a simple example of the practical application of the button method1 suppose three holes are to be bored in a jig-plate according to the dimensions given in ,fig4 #a4 ,a common method of procedure would be as follows3 ,first lay out the centers of all holes to be bored1 by the usual method4 ,mark these centers with a prick-punch and then drill holes for the machine screws which are used to clamp the buttons4 ,after the buttons are clamped lightly in place1 set them in correct relation with each other and with the jig-plate4 ,the proper location of the buttons is very important1 as their positions largely determine the accuracy of the work4 ,the best method of locating a number of buttons depends1 to some extent1 upon their relative positions1 the instruments available1 and the accuracy required4 ,when buttons must be located at given distances from the finished sides of a jig1 a surface plate and vernier height gage are often used4 ,the method is to place that side from which the button is to be set1 upon an accurate surface plate and then set the button by means of the height gage1 allowance being made1 of course1 for the radius of the button4 ,the center-to-center distance between the different buttons can afterwards be verified by taking direct measurements with a micrometer4 ,illustration3 ,fig4 #a4 ,simple ,example of ,work ,illustrating ,application of ,button ,method ,figs4 #b and #c illustrate a method which requires only a micrometer4 ,two of the buttons are set at the correct distance from one edge of the plate by measuring from a parallel strip4 ,obviously1 the micrometer reading will exceed the distance from the center of a button to the edge of the plate1 by the amount equal to the thickness of the parallel strip plus the radius of the button4 ,the center-to-center distance between each pair of buttons is also tested as indicated in ,fig4 #c1 by measuring the overall distance and deducting the diameter of one button4 ,after the buttons have been set and the screws are tightened1 all measurements should be carefully checked4 ,the work is then mounted on the faceplate of the lathe and one of the buttons is set true by the use of a test indicator as shown in ,fig4 #d4 ,when the dial of the indicator ceases to vibrate1 thus showing that the button runs true1 the latter should be removed so that the hole can be drilled and bored to the required size4 ,in a similar manner other buttons are indicated and the holes bored1 one at a time4 ,it is evident that if each button is correctly located and set perfectly true in the lathe1 the various holes will be located the required distance apart within very close limits4 ,illustration3 ,fig4 #b4 ,determining ,distance from ,button to ,edge of ,plate ,another example of work illustrating the application of the button method is shown in ,fig4 #e4 ,the disk-shaped part illustrated is a flange templet which formed a part of a fixture for drilling holes in flanged plates1 the holes being located on a circle #f inches in diameter4 ,it was necessary to space the six holes equi-distantly so that the holes in the flanges would match in any position1 thus making them interchangeable4 ,first a plug was turned so that it fitted snugly in the #a-;inch central hole of the plate and projected above the top surface about inch4 ,a center was located in this plug and from it a circle of three inches radius was drawn4 ,this circle was divided into six equal parts and then small circles inch in diameter were drawn to indicate the outside circumference of the bushings to be placed in the holes4 ,these circles served as a guide when setting the button and enabled the work to be done much more quickly4 ,the centers of the holes were next carefully prick-punched and small holes were drilled and tapped for ,no4 #aj machine screws4 ,after this the six buttons were attached in approximately the correct positions and the screws tightened enough to hold the buttons firmly1 but allow them to be moved by tapping lightly4 ,as the radius of the circle is #c inches1 the radius of the central plug1 inch1 and that of each button1 _/ inch1 the distance from the outside of the central plug to the outside of any button1 when correctly set1 must be #c _/ inches4 ,since there are six buttons around the circle1 the center-to-center distance is equal to the radius1 and the distance between the outside or any two buttons should be #c inches4 ,having determined these dimensions1 each button is set equi-distant from the central plug and the required distance apart1 by using a micrometer4 ,as each button is brought into its correct position1 it should be tightened down a little so that it will be located firmly when finally set4 ,the work is then strapped to the faceplate of a lathe and each button is indicated for boring the different holes by means of an indicator1 as previously described4 ,when the buttons are removed it will be found that in nearly all cases the small screw holes will not run exactly true2 therefore1 it is advisable to form a true starting point for the drill by using a lathe tool4 ,illustration3 ,fig4 #c4 ,testing ,location of ,buttons ,fig4 #g shows a method of locating buttons from the finished sides of a plate1 and this same plate with the five buttons attached is shown in ,fig4 #f4 ,as the dimensions in ,fig4 #g indicate1 the holes must not only be accurate with relation to each other1 but also with reference to the edges of the templet2 therefore1 it is necessary to work from the sides as well as the center4 ,the width of the plate was first measured carefully and found to be #e inches4 ,as the center-to-center distance between buttons ,b and ,c and also buttons ,d and ,e1 is #b inches1 the distance from the center of each outside button to the edge of the plate is #a inch4 ,a -inch parallel was clamped against the side1 as shown in the illustration1 and then the distance from the outside of each button to the outside of the parallel 7#a _/ inch7 was measured in conjunction with the distance ,l from the central button4 ,the distance ,l was obtained by first determining the center-to-center distance ,m which represents the hypotenuse of a right-angled triangle4 ,m #a4be #a4fbe or ,m #a4be #a4fbe #d4jbd #b4jej inches4 ,therefore1 ,l #b4jej #j4fbe #b4fge inches4 ,in this case1 the center button was first located correctly from the sides and end and then the other buttons were set4 ,when doing precision work of this kind1 the degree of accuracy obtained will depend upon the instruments used1 the judgment and skill of the workman1 and the care exercised4 ,a good general rule to follow when locating bushings or buttons is to use the method which is the most direct and which requires the least number of measurements1 in order to prevent an accumulation of errors4 ,locating ,work by the ,disk ,method ,comparatively small precision work is sometimes located by the disk method1 which is the same in principle as the button method1 the chief difference being that disks are used instead of buttons4 ,these disks are made to such diameters that when their peripheries are in contact1 each disk center will coincide with the position of the hole to be bored2 the centers are then used for locating the work4 ,to illustrate this method1 suppose that the master-plate shown at the left in ,fig4 #h is to have three holes a1 b1 and c bored into it1 to the center distances given4 ,illustration3 ,fig4 #d4 ,testing ,concentricity of ,button ,preparatory to ,boring ,hole in ,lathe ,it is first necessary to determine the diameters of the disks4 ,if the center distances between all the holes were equal1 the diameters would1 of course1 equal this dimension4 ,when1 however1 the distances between the centers are unequal1 the diameters may be found as follows3 ,subtract1 say1 dimension y from x1 thus obtaining the difference between the radii of disks ,c and ,a 7see right-hand sketch72 add this difference to dimension z1 and the result will be the diameter of disk ,a4 ,dividing this diameter by #b gives the radius1 which1 subtracted from center distance x equals the radius of ,b2 similarly the radius of ,b subtracted from dimension y equals the radius of ,c4 ,for example1 #j4icj-j4gbj #j4baj or the difference between the radii of disks ,c and ,a4 ,then the diameter of ,a #j4baj #j4hfj #a4jgj inch1 and the radius equals #a4jgj #b #j4ece inch4 ,the radius of ,b #j4icj-j4ece #j4cie inch and #j4cie #b #j4gij1 or the diameter of ,b4 ,the center distance #j4gbj-j4cie #j4cbe1 which is the radius of ,c2 #j4cbe #b #j4fej or the diameter of ,c4 ,illustration3 ,fig4 #e4 ,flange ,templet with ,buttons ,attached ,illustration3 ,fig4 #f4 ,hinge ,jig ,templet with ,buttons ,attached ,after determining the diameters1 the disks should be turned nearly to size and finished1 preferably in a bench lathe4 ,first insert a solder chuck in the spindle1 face it perfectly true1 and attach the disk by a few drops of solder1 being careful to hold the work firmly against the chuck while soldering4 ,face the outer side and cut a sharp ,v-center in it2 then grind the periphery to the required diameter4 ,next fasten the finished disks onto the work in their correct locations with their peripheries in contact1 and then set one of the disks exactly central with the lathe spindle by applying a test indicator to the center in the disk4 ,after removing the disk and boring the hole1 the work is located for boring the other holes in the same manner4 ,illustration3 ,fig4 #g4 ,hinge ,jig ,templet ,illustrated in ,fig4 #f ,small disks may be secured to the work by means of jeweler's wax4 ,this is composed of common rosin and plaster of paris and is made as follows3 ,heat the rosin in a vessel until it flows freely1 and then add plaster of paris and keep stirring the mixture4 ,care should be taken not to make the mixture too stiff4 ,when it appears to have the proper consistency1 pour some of it onto a slate or marble slab and allow it to cool2 then insert the point of a knife under the flattened cake thus formed and try to pry it off4 ,if it springs off with a slight metallic ring1 the proportions are right1 but if it is gummy and ductile1 there is too much rosin4 ,on the other hand1 if it is too brittle and crumbles1 this indicates that there is too much plaster of paris4 ,the wax should be warmed before using4 ,a mixture of beeswax and shellac1 or beeswax and rosin in about equal proportions1 is also used for holding disks in place4 ,when the latter are fairly large1 it may be advisable to secure them with small screws1 provided the screw holes are not objectionable4 ,disk-and-,button ,method of ,locating ,holes ,the accuracy of work done by the button method previously described is limited only by the skill and painstaking care of the workman1 but setting the buttons requires a great deal of time4 ,by a little modification1 using what is sometimes called the 8disk-and-button method10 a large part of this time can be saved without any sacrifice of accuracy4 ,the disk-and-button method is extensively used in many shops4 ,buttons are used1 but they are located in the centers of disks of whatever diameters are necessary to give the required locations4 ,as three disks are used in each step of the process1 it is sometimes called the 8three-disk method40 ,to illustrate the practical application of this method1 suppose six equally-spaced holes are to be located in the circumference of a circle six inches in diameter4 ,to locate these1 one needs1 besides the buttons1 three disks three inches in diameter1 each having a central hole exactly fitting the buttons4 ,it is best to have1 also1 a bushing of the same diameter as the buttons1 which has a center-punch fitted to slide in it4 ,first the center button is screwed to the templet1 and one of the disks ,a1 ,fig4 #i1 is slipped over it2 then a second disk ,b carrying a bushing and center-punch is placed in contact with disk ,a and a light blow on the punch marks the place to drill and tap for ,no4 #b button1 which is kept in its proper place while tightening the screw by holding the two disks ,a and ,b in contact4 ,next the third disk ,c is placed in contact with disks ,a and ,b and locates ,no4 #c button1 and so on until the seven buttons are secured in position4 ,the templet is then ready to be strapped to the lathe faceplate for boring4 ,illustration3 ,fig4 #h4 ,an ,example of ,precision ,work1 and ,method of ,locating ,holes by ,use of ,disks in ,contact ,of course1 it is not possible to use disks of 8standard0 sizes for many operations1 but making a special disk is easy1 and its cost is insignificant as compared with the time saved by its use4 ,one who employs this method1 especially if he also uses disks to lay out angles1 soon accumulates a stock of various sizes4 ,while it is desirable to have disks of tool steel1 hardened and ground1 or1 in the larger sizes1 of machine steel1 case-hardened and ground1 a disk for occasional use will be entirely satisfactory if left soft4 ,another example of work is shown in ,fig4 #aj4 ,this is a jig templet similar to the one illustrated in ,figs4 #f and #g4 ,sketch ,a gives its dimensions and sketch ,b shows the disk-and-button way of locating the holes4 ,a steel square is clamped with its stock against the right-hand edge of the templet and its blade extending across the top4 ,the lower edge of the blade should be located #j4bej inch from the upper edge of the templet by the use of size blocks4 ,a #b-;inch disk1 touching both blade and stock1 locates hole ,c4 ,another #b-;inch disk1 touching the first disk and the square blade1 locates hole ,b4 ,next a disk #a4fjj inch diameter is placed in contact with the two upper disks and locates the center hole ,a2 and1 finally1 the disks for holes ,b and ,c are used to locate holes ,d and ,e4 ,illustration3 ,fig4 #i4 ,locating ,holes on a ,circle and ,equi-distant by using ,disks and ,buttons in ,combination ,two other jobs that illustrate this method may be of interest4 ,the first one1 shown in ,fig4 #aa1 required the locating of nine equally-spaced holes on a circumference of #g inches diameter4 ,in any such case1 the size of the smaller disks is found by multiplying the diameter of the circle upon which the centers of the disks are located by the sine of half the angle between two adjacent disks4 ,the angle between the centers of adjacent disks equals #cfj number of disks4 #cfj #i #dj2 hence1 in this case1 the diameter of the smaller disks equals #g multiplied by the sine of #bj degrees1 or #g #j4cdbjb #b4ebbd inches4 #g-b4ebbd #d4hebf inches1 which is the diameter of the central disk4 ,the templet shown in ,fig4 #ab required two holes on a circumference #f inches diameter1 with their centers #cg degrees #bj minutes apart4 ,to find the diameter of the smaller disks1 multiply the diameter of the large circle by the sine of one-half the required angle1 as in the preceding example2 thus #f sin #ah degrees #dj minutes #b4jhjd inches1 which is the diameter of the two smaller disks4 ,the diameter of the larger disk equals #f-b4jhjd #d4daif inches4 ,very accurate results can be obtained by the disk-and-button method4 ,of course1 absolute exactness is equally unattainable with buttons and a micrometer1 or any other method2 the micrometer does not show the slight inaccuracy in any one chordal measurement1 while in using the disks the error is accumulative and the insertion of the last disk in the series shows the sum of the errors in all the disks4 ,it is only in cases like the one illustrated in ,fig4 #i that we note this1 and then1 though in correcting the error1 we may change the diameter of the circle a very slight amount1 an exceedingly accurate division of the circumference is secured4 ,use of ,two- and ,three-,diameter ,disks ,fig4 #ac illustrates1 on an enlarged scale1 a piece of work requiring great accuracy1 which was successfully handled by an extension of the three-disk method4 ,fourteen holes were required in a space hardly larger than a silver half-dollar1 and1 although the drawing gave dimensions from the center of the circle1 the actual center could not be used in doing the work1 as there was to be no hole there2 moreover1 a boss slightly off center prevented the use of a central disk1 unless the bottom of the disk were bored out to receive this boss1 which was not thought expedient4 ,hence1 the method adopted was to make the plate thicker than the dimension given on the drawing1 and then bore it out to leave a rim of definite diameter1 this rim to be removed after it had served its purpose as a locating limit for the disks4 ,illustration3 ,fig4 #aj4 7,a7 ,layout of ,jig-,plate4 7,b7 ,disk-and-,button ,method of ,locating ,holes ,as the holes ,a and ,b1 which were finished first1 were #j4fjj inch apart and #j4fbe inch from the center1 the rim was bored to #a4hej inch and two #j4fjj-;inch disks1 in contact with the rim and with each other1 located these holes4 ,as hole ,c was to be equi-distant from holes ,a and ,b1 and its distance from the center was given1 the size of the disk for this hole was readily determined4 ,the disks for holes ,a1 ,b and ,c have two diameters2 the upper diameters are made to whatever size is required for locating the disks of adjacent holes1 and they also form a hub which can be used when setting the disks with an indicator4 ,hole ,d was #j4dbai inch from ,b1 and calculations based on this dimension and its distance from the center showed that it was #j4dcge inch from hole ,c4 ,a 8three-story0 disk or button was made for hole ,d4 ,the diameter of the large part was #j4dfhge inch and it overlapped disks ,c and ,b 7the upper sections of which were made #j4cge inch and #j4djfb inch1 respectively71 thus locating ,d4 ,then hole ,f and all the remaining holes were located in a similar manner4 ,the upper diameters of disks ,e and ,d were used in locating disks for other adjacent holes1 as well as a hub for the indicator2 for instance1 to locate a hole with reference to holes ,c and ,d1 the diameter of the new disk and the diameter of the upper part of disk ,d1 were varied to give the required location4 ,the relation between the disks ,b1 ,d and ,f is shown by the side view4 ,illustration3 ,fig4 #aa4 ,example of ,circular ,spacing requiring a ,large ,central ,disk ,it had been decided that no screws should be used in attaching the buttons or disks to the work1 as it was feared that the tapped holes would introduce inaccuracy by deflecting the boring-tools2 therefore the following method was employed4 ,after all the disks were fastened in place by clamps1 a soft solder of low melting point was flowed about them1 filling the work to the top of the rim4 ,when the solder had cooled1 the clamps were removed1 the work transferred to the lathe faceplate1 indicated in the usual way1 and the holes bored by a 8,d0 or 8hog-nose0 drill1 guided by an axial hole in each disk1 which had been provided for that purpose when the disks were made4 ,it was thought that the unequal contraction of the solder and the plate in cooling might throw the holes 8out of square20 however1 careful measurements failed to show any appreciable lack of parallelism in test-bars inserted in the holes4 ,illustration3 ,fig4 #ab4 ,locating ,holes at an ,angle by use of ,disks and ,buttons ,illustration3 ,fig4 #ac4 ,locating ,holes by ,means of ,two- and ,three-,diameter ,disks in ,contact ,accurate ,angular ,measurements with ,disks ,for setting up a piece of work on which a surface is to be planed or milled at an exact angle to a surface already finished1 disks provide an accurate means of adjustment4 ,one method of using disks for angular work is illustrated at ,a in ,fig4 #ad4 ,let us assume that the lower edge of plate shown is finished and that the upper edge is to be milled at an angle a of #cb degrees with the lower edge4 ,if the two disks x and y are to be used for locating the work1 how far apart must they be set in order to locate it at the required angle8 ,the center-to-center distance can be determined as follows3 ,subtract the radius of the larger disk from the radius of the smaller disk1 and divide the difference by the sine of one-half the required angle4 ,illustration3 ,fig4 #ad4 ,obtaining ,accurate ,angular ,measurements with ,disks ,example3 ,if the required angle a is #cb degrees1 the radius of the large disk1 #b inches1 and the radius of the small disk1 #a inch1 what is the center-to-center distance8 ,the sine of one-half the required angle1 or #af degrees1 is #j4bgefd4 ,the difference between the radii of the disks equals #b - #a #a1 and #a #j4bgefd #c4fbd inches4 ,therefore1 for an angle of #cb degrees1 disks of the sizes given should be set so that the distance between their centers is #c4fbd inches4 ,another method of accurately locating angular work is illustrated at ,b in ,fig4 #ad4 ,in this case1 two disks are also used1 but they are placed in contact with each other and changes for different angles are obtained by varying the diameter of the larger disk4 ,the smaller disk is a standard #a-;inch size1 such as is used for setting a #b-;inch micrometer4 ,by this method any angle up to about #dj degrees can be obtained within a very close limit of accuracy4 ,the following rule may be used for determining the diameter of the larger disk1 when both disks are in contact and the diameter of the small disk is known3 ,multiply twice the diameter of the small disk by the sine of one-half the required angle2 divide this product by #a minus the sine of one-half the required angle2 add the quotient to the diameter of the small disk to obtain the diameter of the large disk4 ,example3 ,the required angle a is #ae degrees4 ,find the diameter of the large disk to be in contact with the standard #a-;inch reference disk4 ,the sine of #g degrees #cj minutes is #j4acjec4 ,multiplying twice the diameter of the small disk by the sine of #g degrees #cj minutes1 we have #b #a #j4acjec #j4bfajf4 ,this product divided by #a minus the sine of #g degrees #cj minutes #j4bfajf ---------------------- #c4jjb4 #a - #j4acjec ,this quotient added to the diameter of the small disk equals #a #j4cjjb #a4cjjb inch1 which is the diameter of the large disk4 ,illustration3 ,fig4 #ae4 ,disk-and-,square ,method of ,accurately ,setting ,angular ,work ,the accompanying table gives the sizes of the larger disks to the nearest #j4jjja inch for whole degrees ranging from #e to #dj degrees inclusive4 ,incidentally1 the usefulness of these disks can be increased by stamping on each one its diameter and also the angle which it subtends when placed in contact with the standard #a-;inch disk4 ,,disk ,,diameters ,,for ,,angular ,,measurement ---------------------------------------- ----- ,deg4 ,inch ,deg4 ,inch ,deg4 ,inch ---------------------------------------- ----- #e #a4jiab #ag #a4cdfh #bi #a4ffhj #f #a4aajd #ah #a4cgjh #cj #a4fihc #g #a4acjj #ai #a4ciec #ca #a4gbid #h #a4adii #bj #a4dbjc #cb #a4gfaj #i #a4agjb #ba #a4ddeg #cc #a4gicd #aj #a4aiji #bb #a4dgaf #cd #a4hbfb #aa #a4babj #bc #a4dihj #ce #a4hfjj #ab #a4bccd #bd #a4ebdi #cf #a4hidd #ac #a4beec #be #a4eebd #cg #a4ibie #ad #a4bgge #bf #a4ehje #ch #a4ifed #ae #a4cjjb #bg #a4fjij #ci #b4jjba #af #a4cbcd #bh #a4fchb #dj #b4jcif ---------------------------------------- ----- ,machinery ---------------------------------------- ------------ ,disk-and-,square ,method of ,determining ,angles ,the method shown in ,fig4 #ae for determining angles for setting up work on a milling machine or planer1 possesses several advantages4 ,no expensive tools are required1 the method can be applied quickly1 and the results obtained are quite accurate enough for any but the most exacting requirements4 ,as will be seen1 an ordinary combination square is used in connection with a disk1 the head of the square being set at different points on the blade according to the angle that is desired4 ,theoretically1 a one-inch disk could be used for all angles from about #f degrees up to a right angle1 but in practice it is more convenient and accurate to employ larger disks for the larger angles4 ,the only inaccuracy resulting from this method is due to setting the square at the nearest 8scale fraction0 instead of at the exact point determined by calculation4 ,this error is very small1 however1 and is negligible in practically all cases4 ,the dimension x required for any desired angle a can be found by multiplying the radius of the disk1 by the cotangent of one-half the desired angle1 and adding to this product the radius of the disk4 ,example3 ,the square blade is to be set to an angle of #ae degrees #aj minutes1 using a #b-;inch disk4 ,at what distance x 7see ,fig4 #ae7 should the head of the square be set8 ,cot #g degrees #ce minutes #g4eaac1 and #g4eaac #a #a #h4eaac inches4 ,by setting the square to #h inches 8full10 the blade would be set very close to the required angle of #ae degrees #aj minutes4 ,locating ,work by means of ,size ,blocks ,the size-block method of locating a jig-plate or other part1 in different positions on a lathe faceplate1 for boring holes accurately at given center-to-center distances1 is illustrated in ,fig4 #af4 ,the way the size blocks are used in this particular instance is as follows3 ,a pair of accurate parallels are attached to a faceplate at right angles to each other and they are so located that the center of one of the holes to be bored will coincide with the lathe spindle4 ,the hole which is aligned in this way should be that one on the work which is nearest the outer corner1 so that the remaining holes can be set in a central position by adjusting the work away from the parallels4 ,after the first hole is bored1 the work is located for boring each additional hole by placing size blocks of the required width between the edges of the work and the parallels4 ,for instance1 to set the plate for boring hole ,d1 size blocks 7or a combination of blocks or gages7 equal in width to dimension ,a would be inserted at ,a1 and other blocks equal in width to dimension ,b beneath the work as at ,b4 ,as will be seen1 the dimensions of these blocks equal the horizontal and vertical distances between holes ,c and ,d4 ,with the use of other combinations of gage blocks1 any additional holes that might be required are located in the central position4 ,while only two holes are shown in this case1 it will be understood that the plate could be located accurately for boring almost any number of holes by this method4 ,illustration3 ,fig4 #af4 ,method of setting ,work on ,faceplate with ,size ,blocks or ,gages ,incidentally1 such gages as the ,johansson combination gages are particularly suited for work of this kind1 as any dimension within the minimum and maximum limits of a set can be obtained by simply placing the required sizes together4 ,sometimes when such gages are not available1 disks which have been ground to the required diameter are interposed between the parallels and the work for securing accurate locations4 ,another method of securing a positive adjustment of the work is to use parallels composed of two tapering sections1 which can be adjusted to vary the width and be locked together by means of screws4 ,each half has the same taper so that outer edges are parallel for any position1 and the width is measured by using a micrometer4 ,the size-block method is usually applied to work having accurately machined edges1 although a part having edges which are of a rough or irregular shape can be located by this method1 if it is mounted on an auxiliary plate having accurately finished square edges4 ,for instance1 if holes were to be bored in the casting for a jig templet which had simply been planed on the top and bottom1 the casting could be bolted to a finished plate having square edges and the latter be set in the different positions required1 by means of size blocks4 ,comparatively large jig plates are sometimes located for boring in this way and the milling machine is often used instead of a lathe4 ,the ,master-plate ,method ,when it is necessary to machine two or more plates so that they are duplicates as to the location of holes1 circular recesses1 etc41 what is known as a master-plate is often used for locating the work on the lathe faceplate4 ,this master-plate ,m 7see ,fig4 #ag7 contains holes which correspond to those wanted in the work1 and which accurately fit a central plug ,p in the lathe spindle1 so that by engaging first one hole and then another with the plug1 the work is accurately positioned for the various operations4 ,when making the master-plate1 great care should be taken to have the sides parallel and the holes at right angles to the sides1 as well as accurately located with reference to one another4 ,the various holes may be located with considerable precision by the use of buttons as previously described4 ,of course1 it is necessary to have a hole in the master-plate for each different position in which the work will have to be placed on the faceplate2 for example1 if a circular recess r were required1 a hole r exactly concentric with it would be needed in the master-plate4 ,the method of holding the work and locating it with reference to the holes in the master-plate will depend largely on its shape4 ,the cylindrical blank ,b illustrated1 is positioned by a recess in the master-plate in which it fits4 ,the work is commonly held to the master-plate by means of clamps and tap bolts or by screws which pass through the work and into the master-plate4 ,solder is sometimes used when it is not convenient to hold the work by clamps or screws4 ,illustration3 ,fig4 #ag4 ,master-plate applied to a ,bench ,lathe ,faceplate ,the plug ,p which locates the master-plate1 is first turned to fit the spindle or collet of the lathe and the outer or projecting end is roughturned for the holes in the master-plate1 which should all be finished to exactly the same diameter4 ,the plug is then inserted in the spindle and ground and lapped to a close fit for the holes in the master-plate4 ,the latter1 with the work attached to it1 is next clamped to the faceplate by the straps shown1 which engage a groove around the edge of the master-plate4 ,the first hole is finished by drilling to within1 say1 #j4jje or #j4jjf inch of the size1 and then boring practically to size1 a very small amount being left for reaming or grinding4 ,the remaining holes can then be finished in the same way1 the work being positively located in each case by loosening the master-plate and engaging the proper hole in it with the central plug4 ,it is apparent that by the use of this same master-plate1 a number of pieces ,b could be made which would be practically duplicates4 ,the master-plate method of locating work can be applied in many different ways4 ,it is used for making duplicate dies1 for accurately locating the various holes in watch movements1 and for many other operations requiring great precision4 ,master-plates are quite frequently used by toolmakers when it is necessary to produce a number of drill jigs which are to be used for drilling holes in different parts having the same relative locations1 thus requiring jigs that are duplicates within very close limits4 ,when a master-plate is required1 that is to be used in making duplicates of an existing model1 the holes are bored in the master-plate by reversing the process illustrated in ,fig4 #ag4 ,that is1 the central plug ,p is turned to fit the largest hole in the model and the latter with the attached master-plate blank is clamped to lathe faceplate4 ,the first hole is then bored to within say #j4jjb inch of the finish diameter1 to allow for grinding1 provided the master-plate is to be hardened4 ,the central plug is then turned down to fit the next largest hole and the second hole is bored in the master-plate4 ,this method is continued until all the holes are bored4 ,in order to prevent any change in the position of the master-plate relative to the model1 it may be secured by inserting dowel-pins through both parts1 the work being held to the lathe faceplate by ordinary screw clamps4 ,if the holes in the model do not extend clear through1 a flat plate having parallel sides may be interposed between the model and master-plate to provide clearance between the two and prevent cutting into the model when boring the master-plate4 ,,chapter ,,ii ,,accurate ,,dividing ,,and ,,spacing ,,methods ,toolmakers and machinists occasionally find it necessary to locate a number of equally-spaced holes on a straight line between two points1 or to divide a circle with holes which are equi-distant within a very small limit of accuracy4 ,several dividing and spacing methods are described in this chapter2 some of these methods can1 with slight modification1 be applied in various ways4 ,illustration3 ,fig4 #ah4 ,method of ,drilling ,small ,equally-spaced ,holes in ,rows ,locating ,small ,equally-spaced ,holes in ,rows ,it is sometimes necessary to drill one or more rows of small equally-spaced holes4 ,the best method of doing this work naturally depends1 to some extent1 upon the accuracy required1 but even when a high degree of accuracy is not necessary1 if an attempt is made to lay out the holes and drill them in the ordinary way1 considerable time is usually required and the results are liable to be unsatisfactory4 ,for example1 suppose a row of holes _/ inch in diameter and inch center-to-center distance were to be drilled in a flat plate4 ,some machinists would proceed by first scribing a center-line and then laying out the centers of the holes by means of dividers4 ,a much easier and accurate method is illustrated in ,fig4 #ah1 and is as follows3 ,lay out the first hole and drill it2 then secure a small piece of flat steel for a drill guide1 drill a hole through it1 bevel one corner and scribe a fine line on the beveled section1 as shown in the illustration4 ,align the hole drilled in the guide with the hole in the work1 by inserting a close-fitting plug1 and clamp a scale against one edge of the drill guide so that one of the graduation marks exactly matches with the line on the guide4 ,the edge of the scale must also be located parallel to the center-line of the row of holes to be drilled4 ,now proceed to drill the holes1 setting the drill guide each time1 to whatever graduation line represents the required spacing or pitch of the holes4 ,it is advisable to use a magnifying glass to accurately align the graduation mark on the scale with the line on the drill guide4 ,if two or more rows of holes are to be drilled parallel1 the guide block can be drilled accordingly1 so that the different rows of holes can be finished at the same time4 ,the drill guide block should be relieved slightly in the center so as to insure the ends of the block bearing against the edge of the scale4 ,a toolmaker or machinist can drill a row of holes accurately by this simple method1 in the time required to lay them out in the usual way1 and even though accuracy is not necessary1 it is quicker to drill holes by this method than by the one more commonly employed4 ,use of ,disks for ,locating ,equally-,spaced ,holes ,a simple method of spacing holes that are to be drilled in a straight line is illustrated in ,fig4 #ai4 ,two disks are made1 each having a diameter equal to the center-to-center distance required between the holes4 ,these disks must also have holes which are exactly central with the outside to act as a guide for the drill or reamer4 ,the first two holes are drilled in the work while the disks are clamped so that they are in contact with each other and also with the straightedge as shown4 ,one disk is then placed on the opposite side of the other1 as indicated by the dotted line1 and a third hole is drilled2 this process of setting one disk against the opposite side of the other is continued until all the holes are drilled4 ,when it is necessary to drill a parallel row of 8staggered0 holes1 the second row can be located by placing disks of the proper size in contact with the first row of disks4 ,illustration3 ,fig4 #ai4 ,locating ,equi-distant ,holes in a ,straight ,line by ,means of ,disks and ,straightedge ,a method of using disks1 which is preferable for very accurate work1 is shown in ,fig4 #bj4 ,the disks are clamped against each other and along straightedge ,a by the screws shown1 and if the outside diameters are correct and the guide holes concentric with the outside1 very accurate work can be done4 ,with this device there may be as many disks as there are holes to be drilled1 if the number of holes is comparatively small1 but if it is necessary to drill a long row of holes1 the disks and frame are shifted along an auxiliary straightedge ,b1 the hole in one of the end disks being aligned with the last hole drilled by inserting a close-fitting plug through the disk and hole4 ,adjustable ,jig for ,accurate ,hole ,spacing ,an adjustable jig for accurately spacing small holes is shown in ,fig4 #ba4 ,illustration3 ,fig4 #bj4 ,special ,disk-jig for ,precision ,drilling ,this form is especially adapted for locating a number of equally spaced holes between two previously drilled or bored holes1 and the accuracy of the method lies in the fact that a slight error in the original spacing of the guide bushing is multiplied1 and1 therefore1 easily detected4 ,there are two of these guide bushings ,a and ,b which are carried by independent slides4 ,these slides can be shifted along a dovetail groove after loosening the screws of clamp-gib ,c4 ,to illustrate the method of using this jig1 suppose five equally spaced holes are to be located between two holes that are #ab inches apart4 ,as the center-to-center distance between adjacent holes is #b inches1 slides ,a and ,b would be set so that the dimension x equals #b inches plus the radii of the bushings4 ,a straightedge is then clamped to the work in such position that a close-fitting plug can be inserted through the end holes which were previously drilled or bored4 ,then with a plug inserted through1 say1 bushing ,b and one of the end holes1 the first hole is drilled and reamed through bushing ,a2 the jig is then shifted to the left until the plug in ,b enters the hole just made4 ,the second hole is then drilled and reamed through bushing ,a and this drilling and shifting of the jig is continued until the last hole is finished4 ,the distance between the last hole and the original end hole at the left is next tested by attempting to insert close-fitting plugs through both bushings4 ,evidently1 if there were any inaccuracy in the spacing of the bushings1 this would be multiplied as many times as the jig was shifted1 the error being accumulative4 ,to illustrate how the error accumulates1 suppose that the bushings were #j4jja inch too far apart2 then the distance to the first hole would be #b4jja inch1 to the second hole1 #d4jjb inch1 and finally the distance from the first to the sixth hole would be #aj4jje inches2 consequently1 the distance between the sixth and seventh holes would equal #ab-aj4jje #a4iie inch1 or #j4jje inch less than the required spacing1 assuming1 for the sake of illustration1 that the first and last holes were exactly #ab inches apart4 ,in case of an error of #j4jje inch1 the bushings would be set closer together an amount equal to one-fifth of this error1 as near as could be determined with a micrometer1 and all of the holes would then be re-reamed4 ,illustration3 ,fig4 #ba4 ,adjustable ,jig for ,accurate ,hole ,spacing ,methods of ,accurately ,dividing a ,circle ,sometimes it is necessary to machine a number of holes in a plate so that all the holes are on a circle or equi-distant from a central point1 and also the same distance apart1 within very small limits4 ,a simple method of spacing holes equally is illustrated at ,a1 ,fig4 #bb4 ,a number of buttons equal to the number of holes required are ground and lapped to exactly the same diameter1 preferably by mounting them all on an arbor and finishing them at the same time4 ,the ends should also be made square with the cylindrical surface of the button4 ,when these buttons are finished1 the diameter is carefully measured and this dimension is subtracted from the diameter of the circle on which the holes are to be located1 in order to obtain the diameter d 7see illustration74 ,a narrow shoulder is then turned on the plate to be bored1 the diameter being made exactly equal to dimension d4 ,by placing the buttons in contact with this shoulder1 they are accurately located radially and can then be set equi-distant from each other by the use of a micrometer4 ,in this particular case1 it would be advisable to begin by setting the four buttons which are #ij degrees apart and then the remaining four4 ,the buttons are next used for setting the work preparatory to boring4 7,see 8,button ,method of ,accurately ,locating ,work407 ,illustration3 ,fig4 #bb4 ,four ,methods of ,accurately ,dividing a ,circle ,correcting ,spacing ,errors by ,split ,ring ,method ,another method of securing equal spacing for holes in indexing wheels1 etc41 is illustrated at ,b1 ,fig4 #bb4 ,this method1 however1 is not to be recommended if the diameter of the circle on which the holes are to be located1 must be very accurate4 ,the disk or ring in which the holes are required1 is formed of two sections e and f1 instead of being one solid piece4 ,the centers for the holes are first laid out as accurately as possible on ring e4 ,parts e and f are then clamped together and the holes are drilled through these two sections4 ,obviously1 when the holes are laid out and drilled in this way1 there will be some error in the spacing1 and1 consequently1 all of the holes would not match1 except when plate e is in the position it occupied when being drilled4 ,whatever errors may exist in the spacing can be eliminated1 however1 by successively shifting plate e to different positions and re-reaming the holes for each position4 ,a taper reamer is used and two pins should be provided having the same taper as the reamer4 ,ring e is first located so that a hole is aligned quite accurately with one in the lower plate4 ,the ring is then clamped and the hole is partly reamed1 the reamer being inserted far enough to finish the hole in plate e and also cut clear around in the upper part of plate f4 ,one of the taper pins is then driven into this hole and then a hole on the opposite side is partly reamed1 after which the other pin is inserted4 ,the remaining holes are now reamed in the same way1 and the reamer should be fed in to the same depth in each case4 ,if a pair of holes is considerably out of alignment1 it may be necessary to run the reamer in to a greater depth than was required for the first pair reamed1 and in such a case all the holes should be re-reamed to secure a uniform size4 ,the next step in this operation is to remove the taper pins and clamps or turn index plate e one hole and again clamp it in position4 ,the reaming process just described is then repeated2 the holes on opposite sides of the plate are re-reamed somewhat deeper1 the taper pins are inserted1 and then all of the remaining holes are re-reamed to secure perfect alignment for the new position of the plate4 ,by repeating this process of shifting plate e and re-reaming the holes1 whatever error that may have existed originally in the spacing of the holes1 will practically be eliminated4 ,it would be very difficult1 however1 to have these holes located with any great degree of accuracy1 on a circle of given diameter4 ,circular ,spacing by ,contact of ,uniform ,disks ,when an accurate indexing or dividing wheel is required on a machine1 the method of securing accurate divisions of the circle illustrated at ,c1 ,fig4 #bb1 is sometimes employed4 ,there is a series of circular disks or bushings equal in number to the divisions required1 and these disks are all in contact with each other and with a circular boss or shoulder on the plate to which they are attached4 ,the space between adjacent disks is used to accurately locate the dividing wheel1 engagement being made with a suitable latch or indexing device4 ,when making a dividing wheel of this kind1 all of the disks are ground and lapped to the same diameter and then the diameter of the central boss or plate is gradually reduced until all of the disks are in contact with each other and with the boss4 ,for an example of the practical application of this method see 8,originating a ,precision ,dividing ,wheel40 ,spacing by ,correcting the ,accumulated ,error ,another indexing method of spacing holes equi-distant1 is illustrated by the diagram at ,d1 ,fig4 #bb4 ,an accurately fitting plug is inserted in the central hole of the plate in which holes are required4 ,two arms h are closely fitted to this plug but are free to rotate and are provided with a fine-pitch screw and nut at the outer ends for adjusting the distance between the arms4 ,each arm contains an accurately made1 hardened steel bushing k located at the same radial distance from the center of the plate4 ,these bushings are used as a guide for the drill and reamer when machining the holes in the plate4 ,to determine the center-to-center distance between the bushings1 divide #cfj by twice the number of holes required2 find the sine corresponding to the angle thus obtained1 and multiply it by the diameter of the circle upon which the holes are located4 ,for example1 if there were to be eleven holes on a circle #h inches in diameter1 the distance between the centers of the bushings would equal #cfj -------------- #af4cf degrees4 #b #aa ,the sine of #af4cf degrees is #j4bhae1 and #j4bhae #h #b4beb inches4 ,the arms are adjusted to locate the centers of the bushings this distance apart1 by placing closely fitting plugs in the bushings and measuring from one plug to another with a micrometer or vernier caliper4 ,of course1 when taking this measurement1 allowance is made for the diameter of the plugs4 ,after the arms are set1 a hole is drilled and reamed2 an accurately fitting plug is then inserted through the bushing and hole to secure the arms when drilling and reaming the adjacent hole4 ,the radial arms are then indexed one hole so that the plug can be inserted through one of the arms and the last hole reamed4 ,the third hole is then drilled and reamed1 and this operation is repeated for all of the holes4 ,evidently1 if the center-to-center distance between the bushings is not exactly right1 the error will be indicated by the position of the arms relative to the last hole and the first one reamed2 moreover1 this error will be multiplied as many times as there are holes4 ,for instance1 if the arms were too far apart1 the difference between the center-to-center distance of the last pair of holes and the center-to-center distance of the bushings in the arms1 would equal1 in this particular case1 eight times the error1 and the arms should be re-adjusted accordingly4 ,larger bushings would then be inserted in the arms and the holes re-reamed1 this operation being repeated until the holes were all equi-distant4 ,as will be seen1 the value of this method lies in the fact that it shows the accumulated error4 ,thus1 if the arms were #j4jjje inch too far apart1 the difference between the first and last hole would equal #h #j4jjje #j4jjd inch4 ,this same principle of dividing can be applied in various ways4 ,for instance1 the radial arms if slightly modified1 could be used for drilling equally-spaced holes in the periphery or disk of a plate1 or1 if a suitable marking device were attached1 a device of this kind could be used for accurately dividing circular parts4 ,originating a ,precision ,dividing ,wheel ,there are various methods employed for making accurate indexing wheels for a definite number of divisions4 ,one of these methods1 suitable particularly for small numbers of divisions1 employs a split wheel with a series of taper holes reamed through the two divisions4 ,by shifting the two divisions from point to point 7as explained in connection with sketch ,b1 ,fig4 #bb7 and reaming and re-reaming the taper holes at each shifting1 they may finally be brought very accurately into position4 ,another method that has been employed consists in clamping about the rim of the dividing wheel a number of precisely similar blocks1 fitting close to each other and to the wheel itself4 ,these blocks are then used for locating the wheel in each of its several positions in actual work4 ,a third and simpler method 7a modification of the one last described7 consists in grinding a series of disks and clamping them around a rim of such diameter that the disks all touch each other and the rim simultaneously1 as explained in connection with sketch ,c1 ,fig4 #bb4 ,the wheel described in the following1 which is illustrated in ,fig4 #bc1 was made in this way4 ,illustration3 ,fig4 #bc4 ,precision ,dividing ,wheel ,disks ,a are clamped against an accurately ground face of the wheel ,b and are supposed to just touch each other all around1 and to be each of them in contact with the ground cylindrical surface at x4 ,they are held in proper position by bolts ,c and nuts ,d4 ,the bolts fit loosely in the holes of the disks or bushings ,a so that the latter are free to be located as may be desired with reference to the bolts4 ,one or two improvements in the construction of this type of dividing wheel may be noted before proceeding to a description of the way in which it is made4 ,for one thing1 instead of having an indexing bolt enter the ,v-space between two adjoining disks1 a smaller diameter y is ground on each of them1 over which locking finger or pawl passes1 holding the wheel firmly from movement in either direction4 ,this construction has the advantage of a probable lessening of error by locating on each bushing instead of between two bushings2 moreover1 it gives a better holding surface and better holding angles than would be the case if this smaller diameter were not provided4 ,a second improvement lies in the method of clamping the bushings ,a in place4 ,instead of providing each bolt with a separate washer1 a ring ,f is used4 ,this ring fits closely on a seat turned to receive it on the dividing wheel ,b4 ,when one bushing ,a has been clamped in place1 the disk is locked from movement so that there is no possibility1 in clamping the remaining bushings1 of having their location disturbed in the slightest degree by the turning of the nuts in fastening them in place4 ,the bushings ,a1 of which there were in this case #bd1 were all ground exactly to the required diameters on their locating and locking surfaces4 ,the important things in this operation are1 first1 that the large or locating diameter of the bushing should be exactly to size2 and second1 that this surface should be in exact alignment with the diameter in which the locking is done2 and1 finally1 that the face of the bushing should be squared with the cylindrical surfaces4 ,a refined exactness for the diameter of the locking surfaces is not so important1 as the form of locking device provided allows slight variations at this point without impairment of accuracy4 ,this dimension was kept within very close limits1 however4 ,the truth of the two cylindrical surfaces and the face of the bushing was assured by finishing all these surfaces in one operation on the grinding machine4 ,the sizing of the outer diameter of the bushing1 which was #a4aeh inch1 must be done so accurately that it was not thought wise to trust to the ordinary micrometer caliper4 ,an indexing device was therefore made having a calipering lever with a long end1 in the ratio of #aj to #a1 which actuated the plunger of a dial test indicator of the well-known type made by the ,waltham ,watch ,tool ,co4 ,the thousandth graduations on the dial of this indicator would then read in ten-thousandths1 permitting readings to be taken to one-half or one-quarter of this amount4 ,the final measurements with this device were all taken after dipping the bushings in water of a certain temperature1 long enough to give assurance that this temperature was universal in all the parts measured4 ,it will be understood1 of course1 in this connection1 that getting the diameter of these bushings absolutely to #a4aeh inch was not so important as getting them all exactly alike1 whether slightly over or slightly under this dimension2 hence1 the precaution taken in measurement4 ,wheel ,b was next ground down nearly to size1 great care being taken that it should run exactly concentric with the axis4 ,as soon as the diameter of the surface x was brought nearly to the required dimension as obtained by calculation1 the disks were tried in place4 ,the first one was put in position with its loose hole central on the bolt and clamped in place under ring ,f4 ,the next bushing was then pressed up against it and against the surface x of the wheel and clamped in place4 ,the third one was similarly clamped in contact with its neighboring bushing and the wheel1 and so on1 until the whole circle was completed4 ,it was then found that the last disk would not fill the remaining space4 ,this required the grinding off of some stock from surface x1 and a repetition of the fitting of the bushings ,a until they exactly filled the space provided for them4 ,illustration3 ,fig4 #bd4 ,precision ,dividing ,wheel and its ,indexing ,mechanism ,this operation required1 of course1 considerably more skill than a simple description of the job would indicate4 ,one of the points that had to be carefully looked out for was the cleaning of all the surfaces in contact4 ,a bit of dust or lint on one of the surfaces would throw the fitting entirely out4 ,the temperature of the parts was another important consideration4 ,as an evidence of the accuracy with which the work was done1 it might be mentioned that it was found impossible to do this fitting on a bench on the southern or sunny side of the shop1 the variations of temperature between morning and noon1 and between bright sunshine and passing clouds1 being such that the disks would not fit uniformly4 ,the variation from these minute temperature changes resulted from the different coefficients of expansion of the iron wheel and the steel bushings4 ,the obvious thing to do would be to build a room for this work kept at a constant temperature and preferably that of the body1 so that the heat of the body would make no difference in the results4 ,it was found sufficient in this case1 however1 to do the work on the northern side of the shop where the temperature was more nearly constant1 not being affected by variations in sunshine4 ,the dividing wheel1 the construction of which has just been described1 was made by the ,fellows ,gear ,shaper ,co4 ,it is used for indexing the ,fellows gear cutters in the machine in which the teeth are ground4 ,the indexing mechanism of this machine is shown in ,fig4 #bd4 ,it is operated by a handle or lever pinned to rock-shaft ,h1 to which is keyed arm ,j4 ,pivoted to ,j is a pawl ,k engaging the teeth of ratchet ,l1 which revolves loosely on shaft ,h4 ,this ratchet ,l controls the movement of locking finger ,e4 ,the parts are shown in their normal or locked position in the engraving4 ,as the handle on shaft ,h is pulled in the direction indicated by the arrow1 arm ,j is raised1 carrying the ratchet wheel around to the right4 ,this allows flat spring ,m to drop off of the ratchet tooth1 permitting helical spring ,o to raise latch ,e and thus leave the wheel free4 ,the continued movement of the hand-lever and of rock-shaft ,h1 by means of gear ,n1 intermediate pinion ,p and gear ,q1 causes the indexing pawl ,r1 which is pivoted to gear ,q and acts on the head of one of the bolts ,c 7see ,fig4 #bc71 to index the wheel one step4 ,just before reaching its new location the new tooth of ratchet wheel ,l coming up1 bears down on the top of spring ,m1 pressing latch ,e into place against the tension of coil spring ,o4 ,by this means the wheel is locked in position4 ,when the operator pushes the handle on shaft ,h back again to its position of rest1 the pawl ,r is retracted into position to act on the next bolt head for the next indexing4 ,star-wheel ,l remains stationary on this backward movement1 being prevented from revolving by the notch on the top of the tooth into which spring ,m fits4 ,pawl ,k on its return engages with the next tooth of this wheel1 ready for the next indexing operation4 ,a slight rotary adjustment of dividing wheel ,b1 independent of this indexing mechanism1 is required for the feeding of the machine4 ,this is accomplished by the end movement of latch ,e1 which is pivoted in slide ,s4 ,this slide is pressed to the right by spring plunger ,t1 and is adjusted positively in the other direction by feed-screw ,u1 which is finely graduated to permit accurate adjustment4 ,the accuracy in indexing obtained by the use of a wheel thus made was required to bring the finished cutters within the very narrow limits allowed for them in the final inspection4 ,,chapter ,,iii ,,locating ,,work ,,for ,,boring ,,on ,,milling ,,machine ,it is often desirable to perform boring operations on the milling machine1 particularly in connection with jig work4 ,large jigs1 which because of their size or shape could not be conveniently handled in the lathe1 and also a variety of smaller work1 can often be bored to advantage on the milling machine4 ,when such a machine is in good condition1 the necessary adjustments of the work in both vertical and horizontal planes1 can be made with considerable accuracy by the direct use of the graduated feed-screw dials4 ,it is good practice1 however1 when making adjustments in this way1 to check the accuracy of the setting by measuring the center distances between the holes directly4 ,for the purpose of obtaining fine adjustments when boring on the milling machine1 the ,brown amp2 ,sharpe ,mfg4 ,co4 makes special scales and verniers that are attached to milling machines1 so that the table may be set by direct measurement4 ,by attaching a scale and vernier to the table and saddle1 respectively1 and a second scale to the column with a vernier on the knee1 both longitudinal and vertical measurements can be made quickly and accurately1 and the chance of error resulting from inaccuracy of the screw1 or from lost motion between the screw and nut1 is eliminated4 ,checking ,location of ,holes by ,micrometer-and-plug ,method ,one method of checking the accuracy of the location of holes bored in the milling machine1 is to insert closely fitting ground plugs into the bored holes and then determine the center-to-center distance by taking a direct measurement across the plugs with a micrometer or vernier caliper4 ,for example1 if holes were to be bored in a jig-plate1 as shown in ,fig4 #a1 assuming that hole ,a were finished first1 the platen would then be moved two inches1 as shown by the feed dial2 hole ,b would then be bored slightly under size4 ,plugs should then be accurately fitted to these holes1 having projecting ends1 preferably of the same size4 ,by measuring from one of these plugs to the other with a vernier or micrometer caliper1 the center distance between them can be accurately determined1 allowance being made1 of course1 for the radii of each plug4 ,if this distance is incorrect1 the work can be adjusted before finishing ,b to size1 by using the feed-screw dial4 ,after hole ,b is finished1 the knee could be dropped #a4e inch1 as shown by the vertical feed dial1 and hole ,c bored slightly under size2 then by the use of plugs1 as before1 the location of this hole could be tested by measuring center distances between ,c-,b and ,c-,a4 ,an example of work requiring the micrometer-and-plug test1 is shown set up in the milling machine in ,fig4 #be4 ,the large circular plate shown has a central hole and it was necessary to bore the outer holes in correct relation with the center hole within a limit of #j4jjje inch4 ,the center hole was first bored and reamed to size2 then an accurately fitting plug was inserted and the distances to all the other holes were checked by measuring from this plug4 ,this method of testing with the plugs is intended to prevent errors which might occur because of wear in the feed-screws or nuts1 that would cause the graduated dials to give an incorrect reading4 ,on some jig work1 sufficient accuracy could be obtained by using the feed-screw dials alone1 that is1 without testing with the plugs1 in which case the accuracy would naturally depend largely on the condition of the machine4 ,illustration3 ,fig4 #be4 ,example of ,precision ,boring on ,milling ,machine ,a method that is a modification of the one in which plugs are used to test the center distance is as follows3 ,all the holes are first drilled with suitable allowance for boring1 the location being obtained directly by the feed-screw dials4 ,a special boring-tool1 the end of which is ground true with the shank1 is then inserted in the spindle and the first hole1 as at ,a in ,fig4 #a is finished1 after which the platen is adjusted for hole ,b by using the dial as before4 ,a close-fitting plug is then inserted in hole ,a and the accuracy of the setting is obtained by measuring the distance between this plug and the end of the boring-tool1 which is a combination tool and test plug4 ,in a similar manner1 the tool is moved from one position to another1 and1 as all the holes have been previously drilled1 all are bored without removing the tool from the spindle4 ,another modification of the micrometer-and-plug method is illustrated in ,figs4 #bf and #bg4 ,it is assumed that the plate to be bored is finished on the edges1 and that it is fastened to an angle-plate1 which is secured to the table of the milling machine and set square with the spindle4 ,a piece of cold-rolled steel or brass is first fastened in the chuck 7which is mounted on the spindle7 and turned off to any diameter4 ,this diameter should preferably be an even number of thousandths1 to make the calculations which are to follow easier4 ,the turning can be done either by holding the tool in the milling machine vise1 or by securing it to the table with clamps4 ,in either case1 the tool should be located near the end of the table1 so as to be out of the way when not in use4 ,illustration3 ,fig4 #bf4 ,obtaining ,vertical ,adjustment by ,means of ,depth ,gage and turned ,plug in ,chuck ,after the piece in the chuck is trued1 the table and knee are adjusted until the center of the spindle is in alignment with the center of the first hole to be machined4 ,this setting of the jig-plate is effected by measuring with a micrometer depth gage from the top and sides of the work1 to the turned plug1 as illustrated in ,fig4 #bf4 ,when taking these measurements1 the radius of the plug in the chuck is1 of course1 deducted4 ,when the plate is set the plug is removed from the chuck and the first hole drilled and bored or reamed to its proper size4 ,we shall assume that the holes are to be located as shown by the detail view1 ,fig4 #bf1 and that hole ,a is the first one bored4 ,the plug is then again inserted in the chuck and trued with the tool1 after which it is set opposite the place where the second hole ,b is to be bored2 this is done by inserting an accurately fitting plug in hole ,a and measuring from this plug to the turned piece in the chuck1 with an outside micrometer as indicated in ,fig4 #bg4 ,allowance is1 of course1 again made for the radii of the two plugs4 ,the horizontal measurement can be taken from the side of the work with a depth gage as before4 ,the plug is then removed and the hole drilled and bored to the proper size4 ,the plug is again inserted in the chuck and turned true2 the table is then moved vertically to a position midway between ,a and ,b1 and then horizontally to the proper position for hole ,c1 as indicated by the depth gage from the side of the work4 ,the location can be verified by measuring the center distances x with the micrometer4 ,in a similar manner holes ,d1 ,e1 ,f and ,g are accurately located4 ,illustration3 ,fig4 #bg4 ,adjusting for ,center-to-center ,distance by use of ,plugs and ,micrometer ,if the proper allowances are made for the variation in the size of the plug1 which1 of course1 is made smaller each time it is trued1 and if no mistakes are made in the calculations1 this method is very accurate4 ,care should be taken to have the gibs on all sides fairly tight at the beginning1 and these should not be tightened after each consecutive alignment1 as this generally throws the work out a few thousandths4 ,if the reductions in the size of the plug1 each time it is turned1 are confusing1 new plugs can be used each time a test is made1 or the end of the original plug can be cut off so that it can be turned to the same diameter for every test4 ,if the center distances x are not given1 it is1 of course1 far more convenient to make all the geometric calculations before starting to work4 ,the ,button-and-plug ,method ,the use of the button method as applied to the milling machine1 is illustrated in ,fig4 #bh1 where a plain jig-plate is shown set up for boring4 ,the jig1 with buttons ,b accurately located in positions corresponding to the holes to be bored1 is clamped to the angle-plate ,a that is set at right angles to the spindle4 ,inserted in the spindle there is a plug ,p1 the end of which is ground to the exact size of the indicating buttons4 ,a sliding sleeve ,s is accurately fitted to this plug and when the work is to be set for boring a hole1 the table and knee of the machine are adjusted until the sleeve ,s will pass over the button representing the location of the hole1 which brings the button and spindle into alignment4 ,when setting the button in alignment1 all lost motion or backlash should be taken up in the feed-screws4 ,for instance1 if the button on the jig should be a little higher than the plug in the spindle1 do not lower the knee until the bushing slips over the button1 but lower the knee more than is required and then raise it until the bushing will pass over the button4 ,this same rule should be followed for longitudinal adjustments4 ,illustration3 ,fig4 #bh4 ,accurate ,method of ,aligning ,spindle with ,button on ,jig-,plate ,after the button is set by this method1 it is removed and the plug in the spindle is replaced by a drill and then by a boring-tool or reamer for finishing the hole to size4 ,in a similar manner the work is set for the remaining holes4 ,the plug ,p for the spindle must be accurately made so that the outer end is concentric with the shank1 and the latter should always be inserted in the spindle in the same relative position4 ,with a reasonable degree of care1 work can be set with considerable precision by this method1 providing1 of course1 the buttons are properly set4 ,some toolmakers use1 instead of the plug and sleeve referred to1 a test indicator for setting the buttons concentric with the machine spindle4 ,this indicator is attached to and revolves with the spindle1 while the point is brought into contact with the button to be set4 ,the difficulty of seeing the pointer as it turns is a disadvantage1 but with care accurate results can be obtained4 ,size ,block and ,gage ,method ,another method which can at times be employed for accurately locating a jig-plate in different positions on an angle-plate1 is shown in ,fig4 #bi4 ,the angle-plate is1 of course1 set at right angles to the spindle and depth gages and size blocks are used for measuring directly the amount of adjustment4 ,both the angle-plate and work should have finished surfaces on two sides at right angles to each other1 from which measurements can be taken4 ,after the first hole has been bored1 the plate is adjusted the required distance both horizontally and vertically1 by using micrometer depth gages1 which should preferably be clamped to the angle-plate4 ,if the capacity of the gages is exceeded1 measurements may be taken by using standard size blocks in conjunction with the depth gages4 ,illustration3 ,fig4 #bi4 ,locating ,work from ,edges of ,angle-,plate by means of ,depth ,gages and ,size ,blocks ,it is frequently necessary to bore holes in cast jig-plates or machine parts1 which either have irregularly shaped or unfinished edges4 ,a good method of locating such work is illustrated in ,fig4 #cj4 ,the part to be bored is attached to an auxiliary plate ,a which should have parallel sides and at least two edges which are straight and at right angles to each other4 ,this auxiliary plate with the work1 is clamped against an accurate angle-plate ,b1 which should be set square with the axis of the machine spindle4 ,a parallel strip is bolted to the angle-plate and the inner edge is set square with the machine table4 ,after the first hole is bored1 the work is located for boring the other to the edge of the auxiliary plate1 and horizontal measurements y between the parallel and the plate4 ,these measurements1 if quite large1 might be taken with micrometer gages1 whereas1 for comparatively small adjustments1 size blocks might be more convenient4 ,vernier ,height ,gage and ,plug ,method ,when a vernier height gage is available1 it can often be used to advantage for setting work preparatory to boring in a milling machine4 ,one advantage of this method is that it requires little in the way of special equipment4 ,the work is mounted on an angle-plate or directly on the platen1 depending on its form1 and at one end an angle-plate is set up with its face parallel to the spindle4 ,an accurately finished plug is inserted in the spindle and this plug is set vertically from the platen and horizontally from the end angle-plate1 by measuring with the vernier height gage4 ,after the plug is set for each hole1 it is1 of course1 removed and the hole drilled and bored or reamed4 ,illustration3 ,fig4 #cj4 ,method of ,holding and ,locating ,casting of ,irregular ,shape1 for ,boring ,holes ,the way the plug and height gage is used is clearly illustrated in ,figs4 #ca and #cb4 ,the work1 in this particular case1 is a small jig4 ,this is clamped directly to the machine table and at one end an angle-plate is also bolted to the table4 ,this angle-plate is first set parallel with the traverse of the saddle or in line with the machine spindle4 ,to secure this alignment1 an arbor is inserted in the spindle and a test indicator is clamped to it by gripping the indicator between bushings placed on the arbor4 ,the table is then moved longitudinally until the contact point of the indicator is against the surface plate2 then by traversing the saddle crosswise1 any lack of parallelism between the surface of the angle-plate and the line of saddle traverse will be shown by the indicator4 ,illustration3 ,fig4 #ca4 ,making a ,vertical ,adjustment by ,measuring to ,ground ,plug in ,spindle ,illustration3 ,fig4 #cb4 ,making a ,horizontal ,adjustment by measuring from ,angle-,plate to ,ground ,plug ,when the work is to be adjusted horizontally1 the vernier height gage is used as shown in ,fig4 #cb1 the base of the gage resting on the angle-plate and the measurement being taken to an accurately ground and lapped plug in the spindle4 ,for vertical adjustments1 the measurements are taken between this ground plug and the machine platen as in ,fig4 #ca4 ,locating ,holes to be ,bored from ,center-punch ,marks ,the problem of accurately locating holes to be bored on the milling machine has received much attention1 and the method generally used when accuracy has been required is the button method1 which was previously described4 ,so much time is required for doing the work by this method1 however1 that numerous efforts have been made to obtain equally good results in other ways4 ,illustration3 ,fig4 #cc4 ,diagram ,illustrating ,rapid but ,accurate ,method of ,locating ,holes to be bored on ,milling ,machine ,the increasing demand for rapidity combined with accuracy and a minimum liability of error1 led to the development of the system described in the following3 ,a center-punch mark takes the place of the button1 from which to indicate the work into the proper position for boring4 ,the fundamental principle involved is to lay out1 accurately1 two lines at right angles to each other1 and correctly center-punch the point where they intersect4 ,with proper care1 lines may be drawn with a vernier height gage at right angles1 with extreme accuracy1 the chief difficulty being to accurately center the lines where they cross4 ,for semi-accurate work this may be done with a common center-punch but where extreme accuracy is required this method is not applicable1 as the average man is incapable of marking the point of intersection accurately4 ,the diagram1 ,fig4 #cc1 illustrates1 in a simple way1 the procedure adopted in laying out work by this system4 ,the base ,e is in contact with a surface plate while the line ,,bb is drawn with a height gage2 then with side ,f on the plate the line ,,aa is drawn4 ,it will be seen that these lines will be at right angles to each other1 if the bases ,e and ,f are square4 ,work done by this method must have two working surfaces or base lines1 and these must be at right angles to each other4 ,there is no difficulty in drawing the locating lines ,,aa and ,,bb correctly1 either with a vernier height gage or with a special micrometer gage reading to #j4jjja inch1 the only difficult element being to accurately center-punch the lines where they intersect as at ,d4 ,it is assumed that two holes are to be bored1 so that the intersection at ,c would also be center-punched4 ,the scriber point of the height gage should be ground so that it will make a ,v-shaped line1 as shown by the enlarged sketch ,g1 rather than one which would resemble a saw-tooth1 as at ,h1 if a cross-section of it were examined with a microscope4 ,this is important because when the lines are ,v-shaped1 an accurate point of intersection is obtained4 ,illustration3 ,fig4 #cd4 ,center ,locating ,punch ,illustration3 ,fig4 #ce4 ,center ,enlarging ,punch ,as it is quite or almost impossible to accurately center-punch the intersection of even two correctly drawn lines1 by ordinary means1 the punch shown in ,figs4 #cd and #cf was designed and an extended experience with it on a very high grade of work has demonstrated its value for the purpose4 ,it consists essentially of a small center-punch ,o 7,fig4 #cf7 held in vertical position by a holder ,p which is knurled to facilitate handling4 ,great care should be exercised in making this tool to have the body of the punch straight1 and to have it stand at right angles to the surface to be operated upon1 for the slightest inclination will cause the finished hole to be incorrect1 no matter how carefully the lines are drawn4 ,the #fj-;degree point must be ground true with the axis4 ,the holder for the punch stands on three legs1 located as indicated1 and ground accurately to a taper fit in the holder1 where they are secured by watch screws bearing on their tops4 ,the lower ends are hardened1 and terminate in an angular point of #ee degrees 7the point of the vernier scriber being #fj degrees74 ,the edges are sharp1 and slightly rounded at the ends1 so that the legs will slide along a line smoothly4 ,the points ,v and ,u 7,fig4 #cf7 have edges that are in line with each other1 while the point ,t has an edge at right angles to the other two4 ,the center of the punch is located at equal distances from all the legs1 and is held off the work normally by a leather friction acted upon by a set-screw in the side of holder ,p4 ,illustration3 ,fig4 #cf4 ,section of ,center ,locating ,punch ,illustration3 ,fig4 #cg4 ,section of ,center ,enlarging ,punch ,if this tool is placed upon lines of the form shown at ,g1 ,fig4 #cc1 the legs ,v and ,u may be slid along horizontal line ,b-,b1 ,fig4 #cc1 until the sharp edge of leg ,t drops into line ,a-,a4 ,when this occurs the punch ,o is lightly tapped with a hammer1 and the resulting mark will be accurately located in the center of the intersection of the lines4 ,it is good practice to make the work very smooth before drawing the lines1 and after laying them out1 to stone them so as to remove the slight burr raised in drawing them4 ,a drop of oil is then rubbed into the lines1 and the surplus wiped off4 ,this procedure permits points ,v and ,u to run very smoothly along the line1 and the burr having been removed1 the edge of leg ,t drops into the line very readily with a slight click4 ,as it is not advisable to strike punch ,o more than a very light blow1 it marks the work but slightly1 and a more distinct indentation is made with the follower punch shown in ,figs4 #ce and #cg4 ,this punch is made like the previous one1 so that it will stand at right angles to the work4 ,the sectional view 7,fig4 #cg7 shows the punch ,a supported by the holder ,e which has four legs cut away on the sides so that the point of the punch may be seen4 ,when this punch is in position1 it is struck a sufficiently heavy blow to make a distinctly visible mark4 ,the work is now ready to be placed upon the work table of the milling machine1 and indicated for boring the holes1 an indicator being used in the milling machine spindle4 ,illustration3 ,fig4 #ch4 ,indicator used for ,aligning ,punch ,marks with ,machine ,spindle ,an indicator which has been found especially valuable for this purpose is shown in ,figs4 #ch and #ci4 ,it is of the concentric centering type1 and with it the work is brought concentric with the axis of the spindle4 ,the arbor ,i is provided with a threaded nose on which disk ,d is screwed4 ,this disk has four holes in its rim1 equally-spaced from each other4 ,hardened1 ground1 and lapped bushings b are put into these holes to receive plug ,a which is made a gage-fit both in these holes and in hole ,b in the outer end of sector ,c4 ,this sector is held by a split sleeve to the barrel ,l which carries the #fj-;degree centering-rod ,k that comes into contact with the work to be bored4 ,the spherical base of barrel ,l fits into a corresponding concave seat in the nose of the arbor at ,h1 and is held in place by a spring ,e which connects at one end to the cylindrical stud in the base of the barrel1 and at the other to the axial rod ,m by which it and the other connecting parts may be drawn into place1 and held by the headless set-screw ,j1 bearing on a flat spot on the tang end of the rod4 ,now1 if plug ,a is removed from bushing b the point of the centering-rod ,k may be made to describe a circle4 ,at some point within this circle is located the center-punch mark on the work to be bored4 ,the holes in the rim of the faceplate all being exactly the same distance from an axial line through both the arbor ,i and centering-rod ,k1 it follows that the center mark on the work must be so located by horizontal and vertical movements of the work table that pin ,a may be freely entered in all the four holes in the rim of disk ,d4 ,when that occurs1 the center coincides with the axis of the spindle4 ,the point of the center-punch ,a 7,fig4 #cg7 should have an angle slightly greater than the angle on the centering-rod ,k1 as it is impossible to locate the work in the preliminary trials so that the center of the work will be coincident with the axis of the spindle1 and unless the precaution mentioned is taken1 the true center on the work is liable to be drawn from its proper location when trying to bring the work into such a position that the plug will enter all the holes in the disk4 ,as the work being operated on is brought nearer to the proper location by the movements of the milling machine table1 spring ,g will be compressed1 the center rod sliding back into barrel ,l4 ,this spring is made so that it will hold the center against the work firmly1 but without interfering with the free rotation of the sector ,c around disk ,d4 ,when the work is located so that the plug enters the holes1 the gibs of the machine should be tightened up and the plug tried once more1 to make sure that the knee of the machine has not moved sufficiently to cause the work on the table to be out of line4 ,the work table is now clamped to prevent accidental horizontal shifting1 and the work is drilled and bored4 ,illustration3 ,fig4 #ci4 ,sectional ,view of ,indicator shown in ,fig4 #ch ,in using this indicator the milling machine spindle is not rotated together with arbor ,i1 only the sector being turned around the disk4 ,the tool is set1 however1 in the beginning1 so that the axes of two of the bushings b are at right angles to the horizontal plane of the machine table1 while the axes of the other holes in the disk are parallel with the top of the work table4 ,the centering-rods are made interchangeable and of various lengths1 to reach more or less accessible centers4 ,fig4 #ch shows the indicator with one of the long center-rods in the foreground4 ,the only part of the milling machine on which dependence must be placed for accuracy is the hole in the spindle1 and this is less liable to get out of truth1 from wear such as would impair the accuracy1 than are the knee1 table1 or micrometer screws4 ,the only moving part is the sector1 and this1 being light1 is very sensitive4 ,a series of #bd holes was laid out and bored in one and one-half day by the method described in the foregoing4 ,measurements across accurately lapped plugs in the holes1 showed the greatest deviation from truth to be #j4jjjb inch1 and running from that to accuracy so great that no error was measurable4 ,this same work with buttons would have required considerably more time4 ,illustration3 ,,machinery ,machinery is the leading journal in the machine-building field and meets the requirements of the mechanical engineer1 superintendent1 designer1 toolmaker and machinist1 as no other journal does4 ,,machinery deals exclusively with machine design1 tool design1 machine construction1 shop practice1 shop systems and shop management4 ,the reading matter in ,,machinery is written by practical men and edited by mechanical men of long practical training4 ,each number of ,,machinery contains a variety of articles on machine shop practice4 ,these articles include carefully prepared descriptions of manufacturing methods and current mechanical developments4 ,shop systems and shop managements are ably handled by the foremost writers4 ,every number contains the most extensive and complete record published by any journal1 or in any form1 of new machinery and tools and accessories for the machine shop4 ,a special department is devoted to 8,letters on ,practical ,subjects10 to which practical mechanics contribute their experiences4 ,there is a department of ,shop ,kinks--brief1 concise little contributions which contain ideas of value to the man in the shop or at the drafting table4 ,the mechanical engineer1 machine designer and draftsman are also well provided for in ,,machinery4 ,every number contains articles on the theory and practice of machine design1 on the properties of materials1 and on labor-saving methods and systems4 ,there are reviews of research work in the mechanical field1 and valuable results of carefully made experiments are recorded4 ,the supremacy of ,,machinery in the mechanical field is due to the care with which all matter offered for publication in its pages is scrutinized4 ,only the best of the material offered by mechanical writers is published1 and1 as a result1 its pages contain the most authoritative1 practical and up-to-date mechanical information4 ,,machinery1 #adj-adh ,lafayette ,street1 ,new ,york ,city #ea and #eb1 ,,chancery ,,lane1 ,,london1 ,w4 ,c4 ,heat-,treatment of ,steel ,illustration is one of a series of high-class authoritative1 attractive and well-bound books published by ,,machinery4 ,the strongest claim that can be made for these books is that they have all the characteristics of ,,machinery itself4 ,these books cover comprehensively1 and in a thoroughly practical manner1 the most important subjects in the metal-working field4 ,each book comprises about #cjj pages1 printed on high-grade paper1 with engravings of the same superior type that has made ,,machinery distinctive in its field4 ,the price of each book is #b4ej4 ,special combination offers on a monthly payment plan will be sent upon request4 ,,machinery #adj-adh ,lafayette ,st4 ,new ,york ,city #ea and #eb1 ,chancery ,lane1 ,london1 ,w4 ,c4 ,the ,five ,new ,books ,brought ,out by ,,machinery ,,spur ,,and ,,bevel ,,gearing ,a treatise on the principles1 dimensions1 calculation1 design and strength of spur and bevel gearing1 together with chapters on special tooth forms and methods of cutting gear teeth4 ,,spiral ,,and ,,worm ,,gearing ,a treatise on the principles1 dimensions1 calculation and design of spiral and worm gearing1 together with chapters on the methods of cutting the teeth in these types of gears4 ,,turning ,,and ,,boring ,by ,,franklin ,d4 ,,jones ,associate ,editor of ,,machinery ,a specialized treatise for machinists1 students in industrial and engineering schools1 and apprentices on turning and boring methods1 including modern practice with engine lathes1 turret lathes1 vertical and horizontal boring machines4 ,,planing ,,and ,,milling ,by ,,franklin ,d4 ,,jones ,associate ,editor of ,,machinery ,a treatise on the use of planers1 shapers1 slotters and various types of horizontal and vertical milling machines and their attachments4 ,,heat-,,treatment ,,of ,,steel ,a comprehensive treatise on the hardening1 tempering1 annealing and case-hardening of various kinds of steel1 including high-speed1 high-carbon1 alloy and low-carbon steels1 together with chapters on heat-treating furnaces and on hardness testing4 ,price of each book #b4ej4 ,special combination offers on a monthly payment plan will be sent upon request4 ,,machinery #adj-adh ,lafayette ,st4 ,new ,york ,city #ea and #eb1 ,chancery ,lane1 ,london1 ,w4 ,c4