Modern Machine-Shop Practice Novel Chapters
List of most recent chapters published for the Modern Machine-Shop Practice novel. A total of 286 chapters have been translated and the release date of the last chapter is Apr 02, 2024
Latest Release: Chapter 1 : Modern Machine-Shop Practice.by Joshua Rose.PREFACE.MODERN MACHINE-SHOP PRACTICE is pres
Modern Machine-Shop Practice.by Joshua Rose.PREFACE.MODERN MACHINE-SHOP PRACTICE is presented to American mechanics as a complete guide to the operations of the best equipped and best managed workshops, and to the care and management of engines and boiler
- 186 From the construction, the rivets joining the pieces forming the belt do not come into contact with the surfaces of the pulley, and from the tension of the belt causing it to wedge into the sides of the pulley groove, the driving power is greater than tha
- 185 There are many different methods of lacing a belt, but those here described are generally preferred. Thus referring to Fig. 2687 the lace is first pa.s.sed through holes G and D, the ends being of equal length from the belt and emerging on the side that i
- 184 [Ill.u.s.tration: Fig. 2674.]But when this provision cannot be carried out, pulleys to guide the direction of motion of the belt must be employed; thus in Fig. 2674 are an elevation and plan[39] of an arrangement of these guide or mule pulleys; A B is the
- 183 When the amount to which the leather has been stretched is an unknown quant.i.ty (as is commonly the case), the workman cuts the belt too short, to an amount dictated solely by judgment, following no fixed rule. If, as in the case of narrow belts, the str
- 182 Suppose, now, we take the four divisions on A and the three on B to consider their proportions, and we may say 4 is 1-1/3 times 3, or we may with equal propriety say 3 is 3/4 of 4, hence 4 is not in the same proportion to 3 that 3 is to 4. Let it now be s
- 181 When the pulley is in motion, the centrifugal force imparted to the oil in the reservoir throws it outwardly, causing it to be distributed in an even layer against the inner surface of the sh.e.l.l which encloses and forms the reservoir, thus preventing a
- 180 [Ill.u.s.tration: Fig. 2626.]In Fig. 2625 is shown a patent self-adjusting compression clamp, which is peculiarly adapted to connect shafting that is of proper gauge diameter. It consists of a sleeve A made in two halves, each embracing nearly one-half of
- 179 COUPLINGS FOR LINE OR DRIVING SHAFTS.--The couplings for connecting the ends of line shafts should accomplish the following objects:-- 1. To hold the two shaft ends axially true one with the other.2. To have an equal grip along the entire length of shaft
- 178 An excellent form of countershaft hanger is shown in Fig. 2594, the guide for the slide being adjustable along the arm, and fixed in its adjusted position by means of the set-screws. The bearing is self-adjusting horizontally for alignment. The countersha
- 177 "The process of cold rolling produces a very marked change in the physical properties of the iron thus treated."It increases the tenacity from 25 to 40 per cent., and the resistance to transverse stress from 50 to 80 per cent."It elevates the elastic l
- 176 [Ill.u.s.tration: Fig. 2587.]First prepare a number of rude wooden frames, such as shown in Fig.2585. They are called targets, and are pieces of wood nailed together, with the outer edge face A planed true, and having a line marked parallel with the plane
- 175 The length C of the [V] of the template must not be longer than from 4 to 6 inches, or it will be liable to spring or twist from its own weight. This template is not intended to be used in any sense as a straight-edge to test the truth of the length of th
- 174 [Ill.u.s.tration: Fig. 2561.]If two eccentrics are used, as in a link motion, the lines for setting one eccentric are equally applicable to both; the lap and lead line F being located on the crank-pin side of E when there is a rock shaft, as is supposed t
- 173 [Ill.u.s.tration: Fig. 2548.]If the axial line of the cross-head journal stands truly horizontal, the flat places on the crank pin may be filed horizontally level, with the crank placed on the corresponding and respective dead centres. But as the length o
- 172 [Ill.u.s.tration: Fig. 2531.]It may here be remarked that if the bore of the crank-pin bra.s.ses of the connecting rod is not at right angles to the centre line of the rod itself, the end E, Fig. 2529, might fall either inside or outside, laterally, of th
- 171 Ridges form at the ends of the cylinder bore and at the ends of the guides for the following reasons:-- Referring to the cylinder, the location of the piston stroke in the cylinder bore alters as the connecting-rod keys pa.s.s through the rod, because tha
- 170 [Ill.u.s.tration: Fig. 2515.]REBORING CYLINDERS IN THEIR PLACES ON THE ENGINE.--When a cylinder bore becomes so worn out of cylindrical truth, or becomes grooved or cut, as it is termed, as to require to be rebored, it may be done with the cla.s.s of bori
- 169 Since the babbitt metal in a bearing is apt to close across the bore when cooling after being poured, a mandrel of slightly larger diameter than the diameter of the journal should be used in place of the working journal to run the bearing on. Some effect
- 168 Fig. 2502.]"FLUIDITY OF OILS.--Continuing my remarks on the thinness or fluidity of oils, I wish to call attention to an ingenious arrangement for testing the fluidity when subject to a slight increase of temperature, and also for detecting any tendency
- 167 [Ill.u.s.tration: Fig. 2487.]To enable the removal of bearings for renewal, or to refit them without taking the shaft out, various forms of construction are employed, of which Fig. 2487, which shows a main bearing, is an example.Thus, when the cap is remo
- 166 [Ill.u.s.tration: Fig. 2475.]FITTING BRa.s.sES TO THEIR JOURNALS.--Bra.s.s bores always require fitting to their journals after having been bored, because the finished hole is not a true circle, but too narrow across the joint face, as at F in Fig.2475, i
- 165 [Ill.u.s.tration: Fig. 2465.]Fig. 2465 represents a pipe cutter in which are a pair of anti-friction rollers and a severing tool bevelled on one edge only so as to leave the end of the pipe face cut square, and the piece cut off bevelled on its face; or b
- 164 The joint is made by using, in place of the gauze wire, one or two thicknesses of the pasteboard, duck, or canvas, cut out to the size of the f.l.a.n.g.e, and with the necessary holes to receive the standing bolts and leave the bore of the pipe clear. If
- 163 In this process great care must be taken in cleaning the surfaces before applying them together, as the finest particle of dust will cut scratches, which though imperceptible on sc.r.a.ped surfaces, appear very coa.r.s.e and deep on these smooth ones.The
- 162 [Ill.u.s.tration: Fig. 2429.][Ill.u.s.tration: Fig. 2430.]We now turn our attention to the f.l.a.n.g.es, and apply a square to the crown of the box, bringing the edge of the blade fair with the edge of the box, as shown in Fig. 2428, A representing the bo
- 161 No. 6 is raw limestone (not burned).Take of No. 1, 45 lbs., and of No. 2, 12 lbs. Pulverize finely and dissolve in as much water as will dissolve it and no more--say 14 gallons of water in a tight barrel; and let it be well dissolved before using it.Then
- 160 To line up the bra.s.ses for length we proceed as follows: One of the liners adjusts the length of the rod and the other simply serves to set the key back to its proper height, so that it shall not pa.s.s too far through the keyway, as the wear of the bra
- 159 In cases where the bra.s.ses are difficult to get out of the strap, because of the location or of the size and weight of the parts, a piece of sheet bra.s.s is sometimes placed between the joint faces, and this piece is filed thinner to let the bra.s.ses
- 158 Furthermore the step may be located so as to come against the rod end when the wear has let the key down, and this will prevent the strap from pa.s.sing too far upon the rod, and, therefore, tend to prevent the rod length from being improperly altered fro
- 157 [Ill.u.s.tration: Fig. 2337.][Ill.u.s.tration: Fig. 2338.][Ill.u.s.tration: Fig. 2339.][Ill.u.s.tration: Fig. 2340.][Ill.u.s.tration: Fig. 2341.][Ill.u.s.tration: Fig. 2342.]It will be noticed in Fig. 2331 that the bra.s.s B does not fill the s.p.a.ce in
- 156 For cutting out long narrow keyways, that are too narrow to admit of a machine cutting tool, and for very true holes, not to be cut out in quant.i.ties all of the same dimensions, it has no equal.[Ill.u.s.tration: Fig. 2312.]Hand drifts are sometimes used
- 155 In small nuts, if two are to be filed, a better plan may be followed.The two nuts may be put upon a short piece of screw, as shown in Fig.2301, and screwed firmly together. In doing this, however, it may be found that the nuts will not tighten against eac
- 154 [Ill.u.s.tration: Fig. 2282.]The first thing to do is to mark off the keyway by scribing lines on the surface of the shaft, indicating the location for the feather seat; and for this purpose nothing is better than the key seat rule shown in Fig.2279, in w
- 153 Fig. 2260 represents a three-cornered or "three-square" sc.r.a.per, which is used princ.i.p.ally upon hollow or very small flat surfaces. The half-round sc.r.a.per is employed upon holes, bores, or large concave surfaces, such as bra.s.ses. Both these t
- 152 The work should be held as near down to the surface of the jaws of the vice as will allow the required amount of metal to be filed off without danger of the file teeth coming into contact with those jaws, and should be placed so that the filing operation
- 151 During the backward stroke the forward foot should again take the workman's weight, while he recovers the upright position.For less heavy filing and for smooth filing, the workman should stand more nearly upright and nearer to the work.The heavier the pr
- 150 [Ill.u.s.tration: Fig. 2213.][Ill.u.s.tration: Fig. 2214.][Ill.u.s.tration: Fig. 2215.][Ill.u.s.tration: Fig. 2216.][Ill.u.s.tration: Fig. 2217.]Hand-files are tapered in thickness from their middle towards both the point and the tang, and are, therefore,
- 149 Clearly when the chisel has arrived at position 2, the moulding will be finished to shape, and it is therefore plain that it takes a length of cutter-edge from C to F to cut a moulding whose depth is S, or what is the same thing, C E.But to solve the ques
- 148 [Ill.u.s.tration: Fig. 2170.]The oil groove chisel, Figs. 2169 and 2170, should be wider at the cutting edge than at A for reasons already stated, and of less curvature than the bore of the bra.s.s or bearing it is to cut the oil groove in.[Ill.u.s.tratio
- 147 An excellent mallet for the machinist's use, for driving finished work without damaging it, is formed of raw hide secured in a metal eye that receives the handle. Or for the same purpose a lead hammer is used, being especially serviceable for setting wor
- 146 It is obvious that by slightly bending the elbow and turning either of these hammers over the blows may be caused to be in any required direction, as shown in Fig. 2113. These two hammers are used for the straightening or smithing processes, and not to re
- 145 In the next series, therefore, the rebounds of the iron ball from the iron anvil were measured and recorded, from which it appeared that when the rebound was greater the duration of contact was shorter, and _vice versa_.+----------------+-----------------
- 144 It should be remarked that, according as the angle should be either to right or to left, one or two intermediate pieces are placed on the swing-frame, the slide of which is nearly horizontal. The speed of the driving shaft, supported by the column mention
- 143 Fig. 2069.Fig. 2070.]CHAPTER XXIV.--GEAR-CUTTING MACHINES.[Ill.u.s.tration: Fig. 2071.]The Brainard automatic gear cutter, Figs. 2069, 2070, 2071 and 2072 is arranged to cut spur, bevel, and worm-wheels, and is of that cla.s.s where the manipulations requ
- 142 FOR WOOD-WORKING TOOLS.----------------+-------------+-----------------+---------------- Name of stone. |Kind of grit.|Texture of stone.|Color of stone.----------------+-------------+-----------------+---------------- Wickersly. |Medium to |Very soft. |Gr
- 141 Fig. 2039 represents an emery belt machine, in which the belt runs vertically and its tension is adjusted by the idler pulley shown at the top of the frame.[Ill.u.s.tration: Fig. 2038.]It is obvious that if a piece of work, as A in Fig. 2040, be held stea
- 140 EMERY GRINDING MACHINES. (For grinding-lathes and roll grinding, see article on Lathes.)--Fig. 2017 represents Brown & Sharpe's grinding machine. The bed, the table, and the cross-feed motion of this machine closely resemble those of the planing machine,
- 139 The emery wheel should be of a grade of not less than 60 or more than 70. If it is too coa.r.s.e it leaves a rough edge, which may, however, be smoothed with an oilstone slip. If the wheel is too fine it is apt to _burn_ the cutter, or in other words, to
- 138 PROFILING MACHINE.--The profiling machine is employed mainly to cut the edges of work, and to sink recesses or grooves in the upper surface of the same to correspond to a pattern. A provisional template of the form of the work is fastened on the bed of th
- 137 [Ill.u.s.tration: Fig. 1971.]Obviously the cutter is set on opposite sides of the work centre, according to which side of the groove is to have the radial face. Thus for example, in Fig. 1970, the cutter is set to the left of line R, the radial face of th
- 136 [Ill.u.s.tration: Fig. 1951.]Suppose, for example, that steps, such as shown in Fig. 1950, were required to be cut in a piece of bra.s.s work, and that, the work requiring to be very true, a set of roughing and one of finis.h.i.+ng cutters be used, then t
- 135 [Ill.u.s.tration: Fig. 1928.][Ill.u.s.tration: Fig. 1929.]This tendency, however, is resisted by the pressure on the side A of the slot, which acts, as already stated, to push the cutter back. In starting the cutter therefore, it is necessary to do so at
- 134 The machine has longitudinal feed only, but where it is desired an automatic feed motion can be applied to the elevating screw in the head, giving feed in a vertical direction.The table is arranged to be run back rapidly by power, by a device which is not
- 133 The rear slot is wider and is a segment of a circle. The screw bolts being slackened the back centre is raised, lowered, or tilted to any required position to bring the centre in line with the work axis, and is then clamped in place. One bolt holds this p
- 132 [Ill.u.s.tration: Fig. 1883.]The construction of the bearings for the cutter driving spindle of the machine is as in Figs. 1882 and 1883. A is the spindle having a double cone to fit corresponding cones in the sleeve B, the fit of one to the other being a
- 131 APPENDIX.=Part I.--Test Questions for Engineers= 467 =Part II.--Dictionary of Workshop Terms= 473 FULL-PAGE PLATES.VOLUME II._Facing_ _Frontispiece._ COMPOUND MARINE ENGINE. t.i.tLE PAGE PLATE I. EXAMPLE OF MILLING MACHINE. 10 " II. EXAMPLES OF MILLING M
- 130 =Line Shafting= 187 to 190 Sizes of 187 Cold rolled shafting 187 Distance between bearings of line shafting 187 Tests of hot rolled and cold rolled shafting 188 Collars for shafting 189 Diameters of line shafting 189 The strength of line shafting 190 Spee
- 129 BY JOSHUA ROSE, M.E.ILl.u.s.tRATED WITH MORE THAN 3000 ENGRAVINGS VOLUME II.NEW YORK CHARLES SCRIBNER'S SONS 1888 COPYRIGHT, 1887, 1888.BY CHARLES SCRIBNER'S SONS.Press of J. J. Little & Co.Astor Place, New York.CONTENTS.VOLUME II.PAGE CHAPTER XXII.=MIL
- 128 In Fig. 1862 is represented a nut threading or tapping machine. The vertical spindles have spring sockets in which the taps are held, so that they can be inserted or removed without stopping the machine. The nuts are fed down the slots of the inclined pla
- 127 [Ill.u.s.tration: Fig. 1846.][Ill.u.s.tration: Fig. 1847.]The three-cutter die would in this case cut the perfectly circular form of Fig. 1847.Now, suppose both of the dies to have been made or set to some certain diameter--in fact, presume them to be mad
- 126 [Ill.u.s.tration: Fig. 1822.]The construction of the head D and clutch and ring H is shown in Figs.1821 and 1822.The body F is bolted by the f.l.a.n.g.e I to a face plate in the live spindle or shaft of the machine, and through slots in this body pa.s.s t
- 125 The face F of the tool is ground at an angle in the direction of I, so that the tool shall take its cut gradually, and that the whole length of the tool cutting edge shall not strike the cut at the same instant, which would cause a sudden strain liable to
- 124 A very old but a very excellent device for hand drilling when no drilling machine is at hand is the drilling frame shown in Fig. 1791, which consists of two upright posts A, and two B, placed side by side with s.p.a.ce enough between them to receive and g
- 123 Fig. 1765 represents the auger bit, which is provided with a conical screw S which pulls it forward into the wood. Its two wings W have cutting edges at D, D, which, being in advance of the cutting edges A, B, sever the fibre of the wood, which is afterwa
- 122 [Ill.u.s.tration: Fig. 1744.]In addition to its value as an adjustable boring tool this device may be used to cut out sweeps and curves, and is especially adapted to cutting those of double eyes. This operation is shown in Fig. 1744, in which D is the dou
- 121 -------+---------------------+-------------------- 1/4 | -- -- 3/16| -- -- 3/16 9/32 | -- -- -- | -- -- -- 5/16 | -- 1/4 -- | -- 15/64 -- 11/32| -- -- -- | -- -- -- 3/8 | -- 9/32 -- | -- 9/32 -- 13/32| -- -- -- | -- -- -- 7/16 | 11/32 -- -- | 11/32 -- --
- 120 [Ill.u.s.tration: Fig. 1716.]Fig. 1716 represents the flat drill, which has three cutting edges, A, B, and C. The only advantages possessed by the flat drill are that it will stand rougher usage than the twist drill, and may be fed faster, while it can be
- 119 Fig. 1697 represents a special machine for boring pulleys, &c. The advantage possessed by this cla.s.s of machine is fully set forth in the remarks upon Boring and Turning Mills, and with reference to Fig. 725.The tool bar is fed vertically to the rotatin
- 118 1683, and the latter operates a worm W, Fig. 1684, engaging a worm-wheel W, which drives the bevel gear _a_, shown by dotted circles in Fig.1685; _a_ drives the bevel gear _c_ upon the sleeve _o_, which has journal bearing (in the frame A of the machine)
- 117 Fig. 1677 represents a drilling machine by Prentice Brothers, of Worcester, Ma.s.sachusetts. Motion for the cone pulley A is received by pulleys B and is conveyed by belt to cone pulley C, which is provided with back gear, as shown; the driving spindle D
- 116 It is sometimes necessary, however, that a tool of the form in Fig. 1652 be used, as, for example, to shape out the surface of a slot, and when this is the case the tool should be shaped as in Fig. 1651, the bottom face having ample clearance (as, say, 15
- 115 Another excellent method is to balance the bed on three points, two at one end and one at the other, and to then pack it up equally at all four corners.To test if the surface of a piece of such work has been planed straight, the following plan may be purs
- 114 [Ill.u.s.tration: Fig. 1616.]The [T]-shaped slots _f_, _g_, _h_, are to receive the heads of bolts as shown in Fig. 1616. The bolt head is rounded at corners _a_, _b_, and the square under the head has the corresponding diagonal corners as _c_ also rounde
- 113 PLANER BEDS AND TABLES.--The general forms of the beds of small planers are such as in Figs. 1557 and 1558, and those of the larger sizes such as shown in Fig. 1563.It is of the first importance that the [V]-guideways in these beds should be straight and
- 112 [Ill.u.s.tration: Fig. 1577.][Ill.u.s.tration: Fig. 1578.][Ill.u.s.tration: Fig. 1579.]Fig. 1579 is a front view, and Fig. 1580 a sectional top view, of a sunk vertical slide, corresponding to that shown in Figs. 1573 and 1578, but in this case the gib ha
- 111 [Ill.u.s.tration: Fig. 1565.]Fig. 1565 represents a planer by William Sellers and Co., of Philadelphia, Pennsylvania. This planer is provided with an automatic feed to the sliding head, both horizontally and vertically, and with mechanism which lifts the
- 110 [Ill.u.s.tration: Fig. 1555.][Ill.u.s.tration: Fig. 1556.]The iron planing machine, or iron planer as it is termed in the United States, is employed to plane such surfaces as may be operated upon by traversing a work table back and forth in a straight lin
- 109 [Ill.u.s.tration: Fig. 1541.]The ram or bar is provided with a rack (Z, Fig. 1545) which engages with a pinion S, Fig. 1541, H being the driving shaft driven by the belt cones A and B. These two cones are driven by separate belts, but from the same counte
- 108 [Ill.u.s.tration: Fig. 1522.]The base A is bolted to the work table, and is in one piece with the fixed jaw B. The movable jaw C is set up to meet the work by hand, and being free to move upon A may be used for either taper or parallel work.To fasten C up
- 107 [Ill.u.s.tration: Fig. 1504.]Suppose the slide to be on its return stroke in the direction of L, and F be rotated as denoted by the arrow, then the pawl C will be actuating wheel A as denoted by its arrow, but if C be moved over so as to engage D as denot
- 106 The following, on some experiments upon the elasticity of wires, is from the report of a committee read before the British a.s.sociation at Sheffield, England."The most important of these experiments form a series that have been made on the elastic prope
- 105 By an Order in Council dated August 23rd, 1883, and which took effect on March 1st, 1884, the standard department of the British Board of Trade subst.i.tuted for the old Birmingham wire-gauge the following:-- +-------------+--------------++---------------
- 104 If less than three straight-edges or parallel strips are to be trued they must be trued to a surface plate or its equivalent, but if a pair are to be made they should have the side faces made true, and be riveted together so that their edges may be trued
- 103 For marking upon one surface a line parallel to another surface, the scribing block or surface gauge shown in Fig. 1458 is employed. It consists of a foot piece or stand D, carrying a stem. In the form shown this stem contains a slot running centrally up
- 102 This process may, in many cases, be artificially a.s.sisted. Suppose, for example, a washer is too large in its bore; it should have its hole and part of its radial faces filled with fire-clay, as shown in Fig. 1439, in which A is the washer and B B the c
- 101 | | ference. | | ference. | -------------+--------+-----------+--------+-----------+-------------- | Ins. | | Ins. | | After 1st dip| .50 | .86 | .08 | .14 | " 2nd " | .99 | 1.71 | .08 | .14 | " 3rd " | 1.47 | 2.54 | .26 | .45 | " 4th " | 1.92 | 3.3
- 100 Fig. 1430.]The plate was subjected to fifty heatings to redness and subsequent coolings in water of ordinary temperature. At every tenth cooling accurate measurements were taken of the contraction in superficial dimensions, and Fig. 1430 shows the final f
- 99 The bands for this purpose are usually of wrought iron, and require in the case of irregular surfaces to be driven on by hammer blows, so that the fit may be correct. As the band is forced on a heavy hammer is held against it, to prevent its moving back a
- 98 Let the length of the wheel bore be 7 inches long, and the amount allowed for forcing be .004 inch, and one end of the wheel bore will have been forced (by the time it is home on the axle) over the length of 7 inches of the axle-seat, whose diameter was .
- 97 Fig. 1417, for example, represents the ordinary form, the points being rounded; hence, when the legs are closed the point of contact between the inside and outside calipers will be at A, while when they are opened out to their fullest the points of contac
- 96 What system can we adopt that will enable workmen of limited capacity to do work that will be practically accurate? The taper bolt for certain purposes presents a very decided advantage. Bolts may be made practically of the same diameter, but holes cannot
- 95 [Ill.u.s.tration: Fig. 1392.][Ill.u.s.tration: Fig. 1393.][Ill.u.s.tration: _VOL. I._ =DIVIDING ENGINE AND MICROMETER.= _PLATE XV._ Fig. 1385.Fig. 1386.Fig. 1387.Fig. 1388.Fig. 1389.Fig. 1390.Fig. 1391.]Fig. 1392 represents a vernier caliper, in which the
- 94 [Ill.u.s.tration: Fig. 1375.]Fig. 1375 shows a similar reading, in which the points do not coincide with the cross threads of the microscope.[Ill.u.s.tration: Fig. 1376.]Fig. 1376 shows the microscope adjusted for testing by turning the circle a quarter r
- 93 If the degree of contact is regulated by devices connected with the moving mechanism of the machine it is indirect, and may vary from causes acting upon that mechanism. But if it is regulated between the work and the moving piece that measures it, nothing
- 92 At the time the Government established the use of the standard system of screw threads in the navy yards, ten sets of gauges were ordered from a manufacturer. His firm procured a duplicate set of these and took them to the navy yard in Boston and found th
- 91 The reason for running the lathe at a comparatively fast speed is that the tool is then less likely to be checked in its movement by a seam or hard place in the metal of the bolt, and that, even if the metal is soft and uniform in its texture, it is easie
- 90 [Ill.u.s.tration: Fig. 1310.]It is obvious that the sc.r.a.per may be given any required shape to meet the work, Fig. 1310 representing a sc.r.a.per of this kind; but it must in this case be fed endways only to its cut, if the work is to be cut to fit the
- 89 1286, the heel being pressed down firmly upon the tool rest. The cut is carried along the work by revolving the handle upon its axis, and from the right towards the left, at the same time that the handle is moved bodily from the left towards the right. By
- 88 [Ill.u.s.tration: Fig. 1266.][Ill.u.s.tration: Fig. 1267.]The half bearing B, Fig. 1266, is chucked upon a half-round mandrel, C being the spherical surface to be turned, a sectional view of C being shown in Fig. 1267.[Ill.u.s.tration: Fig. 1268.]In Fig.
- 87 It is obviously necessary, in cutting multiple threads in this way, to so select the change wheels that the driving gear contains a number of teeth that is divisible without leaving a remainder by the thread to be cut: thus, for a double thread the teeth