UC-NRLF J V A/^ iCENTS ; iiiiiiir B 3 Dlfl fl2i MACHINE STOPS AND LOCKING DEVICES BY JOSEPH G. HORNER MACHINERY'S REFERENCE BOOK NO. 112 PUBLISHED BY MACHINERY, NEW YORK 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 112 MACHINE STOPS, TRIPS AND LOCKING DEVICES BY JOSEPH G. HORNER CONTENTS Machine Stops, Trips and Reversing Mechanisms Clamping and Locking Devices Applied to Machine Tools - - Copyright, 1913, The Industrial Press, Publishers of 49-55 Lafayette Street, New York City MACHINERY, 3 25 CHAPTER I MACHINE STOPS, TRIPS AND REVERSING MECHANISMS In recent years, stops, trips and reversing mechanisms have been applied to a vast number of machine tools. The stops employed vary from the simple adjustable stop, tappet or dog, to the mechanisms in which these are combined with cushion devices, means for reversing feed movements, etc. It may be advisable at the outset to call attention to the difference between a "self-acting" and an "automatic" movement. Many machines which are not wholly automatic contain self-acting movements. A slide-rest is self-acting, though the lathe is not automatic, because the movements of the slides have to be thrown in and out by the operator. The greater number of turret lathes are semi-automatic or self-acting, as distinct from the automatic or "full automatic" screw machine. A number and grinders, in which all the movements proceed without intervention from the attendant, are also in the class with the fully automatic machines. It is in these classes of machines that the highest developments of the mechanisms to be considered of gear-cutters are found. There are two kinds of stops: "Dead" stops are those which positively arrest a movement, and gage a length or diameter in repetitive work; "trip" stops or "trips" throw out a movement, reverse it, or throw it Dead stops alone are not sufficient to check a power feed or movement; some means must also be provided to throw out the feed. Then a dead stop may or may not be incorporated to form a positive check. In many cases the tools themselves, as in some turret-lathe work, constitute dead stops, and render the provision of in again. self-acting additional stops unnecessary. A dead stop is used in hand-operated mechanisms to prevent the operator from moving the slide or other portion further than the predetermined limit, thus guarding against error, and insuring a duplication of dimensions without the need for measurement or gaging. Again, *it is often possible to throw out a dead stop temporarily, and go past it for certain purposes, such as inspection, and again throw it in at the same setting as before. A number of dead stops may be located close together, to enable selection to be made at will or in regular rotation, as in the case of a turret one for each tool-hole. Frequently duplex stops are arranged, to enable the choice of two distances for a single slide, one stop being thrown out of the way. Fine adjustment is in some cases provided for a dead stop, so that a very precise setting can be obtained. An important point in the design of dead stops is that of rigidity; a solid abutment should always be used, and any excessive overhang tending to cause springing must be avoided; otherwise accurate results are impossible. In the operation of a hand turret lathe or other ma- 347578 4 \ TRIPS AND LOCKING DEVICES ;: ' chine tool there iV llfcceasarily a great deal of banging and rough treatment, especially in the hands of a careless operator, and weak and badly-supported stops will cause unsatisfactory work. The binding arrangement for a stop must also be efficient, so that it will not slip and cause a batch of work to be turned out to wrong dimensions. The hardening of contact surfaces is also advisable for preventing wear and bruising that would affect the dimensions of work produced. The position and method of attachment of a dead stop depends on the class of machine and the design. Where a sliding table has to be stopped, it is in many cases possible to attach the stops or dogs by means of a bolt and T-slot in the edge of the table, this being a very simple method and permitting easy adjustment; or a round rod may Machinery, N. Y. Fig. 1, Dead Stops of a Type used on a Cutter-grinding Machine held in bearings on the edge of the table, and adjustable dogs be clamped to the rod by set-screws, or by split ears or lugs. Another method is to have a fixed stop bolted, to the table edge, and adjustable "be dogs attached to a rod in front, these being struck by the stop according to the momevents of the table. A favorite device for short slides, such as the cross-slides of turret lathes, is to attach the stops to a rod or screw passing through a hole in the slide, the faces of the latter coming into contact on each side alternately with the stops. Plain cylindrical parts, if of small diameter, are often controlled by a collar or lug, clamped to them by means of a set-screw, and arranged to encounter the face of the bearing through which the part moves. It is evidently impossible to show all the different kinds of stops which are in use on various machine tools, but the following selection of typical examples embodies the principles involved in the design of all stops. Slight modifications are made in different machines. TRIPS AND REVERSING MECHANISMS shown the simplest possible kind of dead stop applied a cutter grinding machine. We have here a T-slot in the edge of the moving table A, receiving the heads of the bolts which clamp the two stop-plates through the medium of knurled nuts. The In Fig. 1 is to the table of plates strike the block B on the transverse table. Fig. 2 shows a modification of the same In this case the principle. sliding head A of a vertical milling machine is to be stopped in one direction only the downward and a projection stands out from the slide A to encounter the end of the stopscrew in the block 5, which is clamped in a T-slot on the fixed head. After adjusting B approximately in position up or down in the slot, by the lever, the final adjustment is made by the knurled-head screw, which is finally locked by its nut. The screw does not, however, pro- vide a precise means of setting to In some any exact measurement. cases, therefore, such a stop-screw has a micrometer adjustment, Fig. 3. The head of the screw is graduated, so that the screw can be adjusted by a known amount a manifest advantage in fine work. The body of the stop is split, thus providing positive means for binding the stop- screw. An illustration of the stop-screw or rod passing through a hole in the moving slide is shown in Fig. 4. The example shown is that of a cross-slide of a turret lathe. The Machinery, Jf. Y. stop-screw in this case also serves the purpose of moving the rest along through the medium of the handwheel and the miter gears; frequently, however, a separate plain rod is used, parallel with the screw, and carrying split clamped dogs instead of the double lock-nuts, shown in Another example of the use of double nuts is shown in Fig. 7, Fig. 4. illustrating the rear end of a cross-slide for a turret lathe. The stopscrew is tapped into the fixed slide, and passes through an extension on the moving slide. This arrangement serves as a stop for both front and back tools. In a modification, Fig. 18, two screws are used locked with nuts, the ends of the screws being struck by a pin screwed Fig. 2. Dead Stop used on a Vertical Milling Machine No. 112 6 STOPS, TRIPS AND LOCKING DEVICES moving slide. The advantage of both these designs of stops that they are perfectly central, and are therefore better than those classes of stops which are set at the side of the moving slide. The combination of two stops, to provide the choice of two lengths, into the is is common. end A is shown in Fig. 5, showing the rear The main screw A, with a locking nut, abuts case of this kind of a turret slide. Machinery, N.Y. Fig. 3. Stop-screw with Micrometer Adjustment against the back of the saddle or base, and forms one dead stop. An adjustable block B, bolted to the edge of the slide, carries a pivoted dog C, which when dropped down into the position indicated in the view A flat to the left, strikes against a facing on the back of the base. spring D, screwed to B, presses against the tail of C and maintains it Fig. 4. Stop-rod passing through a Hole in a Turret Lathe Cross- slide If C is not required, it is swung up into the horizontal where the flat spring also retains it. A simple kind of stop for round spindles is shown in Fig. 6. The example shown is used on a sensitive drill press, and consists only of a split collar, which arrests the downward travel of the spindle by in position. position, striking against the top bearing. One of the most valuable principles in stop construction is that of the rotary disk carrying several stops, any one of which may be brought into action, either in a selective manner that is, according to the wish of the operator or in automatic fashion one or more stops being made a particular tool or set of tools. In this way comsecured, and the stops are in full sight and easily accessible, to act only for pactness is TRIPS AND REVERSING MECHANISMS I! I! II p. 35 If 8 STOPS, TRIPS No. 112 AND LOCKING DEVICES Machinery, y. T. Fig. 9. Dead Stops used on a Turret Lathe of German Make TRIPS AND REVERSING MECHANISMS which was not the case with some stops, such as, for example, a set of 9 of the older designs of multiple bars laid side by side and used flat for turret stops. Fig. 8 illustrates a rotating type of stop, adopted for the cross-slide saddle of the turret lathe, there being one stop-rod for each tool on the cross-slide turret. The head A is mounted on the end of a shaft that is rotated simultaneously with the turret, and each of the stop-rods is adjusted independently and secured with a nut, the rod passing through the body of the bolt. Each rod in turn abuts XacMnery.y.T. Fig. 10. Turret Lathe Stops used en the Pratt & Whitney Turret Lathes against the bar B, held in a bracket bolted to the front of the lathe The adjustment of this bar is effected by loosening the set-screw and sliding it through the bracket; on tightening the set-screw, it bears down on a flat milled on the bar, and forms a positive check bed. to slipping. Another application is shown in Fig. 9. This arrangement is applied end of the Pittler turrets, which are mounted on a horizontal axis. There are sixteen holes in the turret for tools, and a stop is provided for each hole. All the rods are held in the rim of a disk secured to the rear end of the spindle, on the other end of which to the rear the tool disk or turret is secured. The turret slide one stop-rod at a time against the fixed bed. An arrangement of multiple stops, A travels, bringing "selected" by a radial action, 10 No. 112 STOPS, TRIPS AND LOCKING DEVICES circle, is used in the Pratt & Whitney turret lathes. held in an adjustable bracket A, Fig. 10, bolted to the front side of the bed, set-screws being used for clamping; three of these only are visible in the view. As the turret rotates, a cam B, cut on though not set in a Each stop-rod is Machtnery,N.Y. Fig. 11. Rotating Stop-bar used on Turret Lathe its base, operates a roller C mounted on a pivoted lever D, and thus brings the flat end of another lever E, which is secured to the shaft of D, into line with one or another of the stop-rods, corresponding to the position of the tool-holes in the turret. The lever E is backed up by a lug projecting from the turret slide (not shown), taking the thrust, and eliminating spring. A type of rotating stop which has been extensively adopted by turret lathe manufacturers during recent years is illustrated in Fig. 11. The TRIPS AND REVERSING MECHANISMS 11 principle is that of fitting a rotating slotted bar A somewhere in front of the turret slide, and gearing it up to the turret to turn in unison with the latter, so that a new face of the bar will be presented for each turret face presented to the work. T-slots in the bar provide for the attachment of stop-blocks or nuts, any number of which may be used on one face. As the turret slide travels along, these nuts come against either a trip lever or a dead stop which lies in their path, and so throw out the feed, and generally also act as dead stops. In the illustration, the nuts which happen to be on the face nearest the turret are touched by the bar B, and, by forcing this down, operate a rod that passes through the base, thus dropping the worm-box C and stopping the feed. On the Alfred Herbert hexagon turret lathes a refinement of this type of stop is introduced for the purpose of obtaining the very finest limits in regard to length, by enabling uniform pressure to be put on the stops, Machinery, y. Tig. 12. Enlarged Detail of the Indicator of the Device shown in Fig. 13 independent of changes in the pressure on the cutting tools as they become dull. Fig. 13 shows the appearance of the saddle with the hexagon stop-rod in front, and the pilot handle or spider. In front of the latter is a disk A, rotating with the shaft, and carrying three adjustable dogs (see the detailed view, Fig. 12) with index lines upon them. The saddle has a fixed sector with three lines corresponding with those on the dogs. After the feed has been tripped by the contact of one of the stops on the bar with the end of the vertical plunger seen in Fig. 13, the saddle can be moved a short distance by hand up to a dead stop. When the saddle is hard up against this stop, one of the dogs on the disk is set to come opposite one of the three index lines on the sector. The dog thus forms an accurate means of measuring the pressure on the dead stop. If more than one length is required the two other dogs may be brought into use. The combined trip and dead stop is found in other machines besides turret lathes. Fig. 14 represents the front of a milling machine table, No. 112 12 STOPS, TRIPS AND LOCKING DEVICES with a trip dog A. which presses down the plunger B, and through a pair of levers throws out the feed. The stops C are set to abut against the block which receives B, and thus act as dead stops, positively arresting the table, so that exact lengths can be milled. If the milling cutter simply has to clear over the ends of the work, the dead stops need not be set, but if the travel has to be stopped at definite positions, they are brought into employment. When a feed has to be tripped, the actual medium by which it is thrown out depends on circumstances; it may be either through shifting belts, by sliding clutches toothed or friction or through a dropworm. The difficulty with toothed clutches is that of insuring the reengagement of the teeth. They are reliable enough, when hand- Machinery,N. T. Fig. 13. Rotating Stop-bar and Accurate Indicator used Herbert Hexagon Turret Lathe when an attempt made oil the Alfred mechanby springs or a lever. To render the action absolutely precise, an element must be included to cause both the release and the engagement to take place at an operated, but ism may fail is to render the self-acting, unless the clutches are actuated A spring plunger is the device often adopted. A spring is compressed by the movement of the striking lever, which at the same time releases a trigger or catch, setting the spring free to push the clutch into engagement. This method is obviously capable of various applications. The springs may be actuated by a lever or by cams or by other means. A latch or latches lock the mechanism, rendering it impossible to throw any other movement in until they are released. This feature is worked out in various ways and is embodied in several gear-cutting machines to prevent interference between the indexing and cutting operations. instant. TRIPS AND REVERSING MECHANISMS 13 No. 112 14 STOPS, TRIPS AND LOCKING DEVICES q_, . 02 o * 1 Vljw] "Rd 5 a g, 1 a> 3J S 8 w -< 3 o> fe CG -H 9| ^ *S Q, i : ^ 3 O r* b w> 5 | ^ S O) a "o fl S g r H s 0> ' rt S h a " ** qs oj *H ^2 <C *j J3 TRIPS AND REVERSING MECHANISMS 15 which actuates lever D through a link, thus throwing out the clutch, and stopping the feed. A double trip and reversing mechanism for a large grinding machine is shown in Fig. 16. In this arrangement the dog is bolted to the edge of the moving table, and strikes against adjustable dogs on the flat striking bar, which is connected by levers to the toothed clutch. In this design the table feeds and reverses so long as the driving mechanism is running. This brings us to the question of locking, that is retaining a clutch or other gear in mesh as long as it has to drive. Without some means of locking, there is nothing to prevent the Machine t Fig. 19. Method of Locking Clutch by Spring Plunger clutch from disengaging under the effects of vibration. and most common method is end, or with a roller, which The simplest a spring plunger with a pointed slips down along a beveled end on one of the levers, or into recesses, there being many ways of accomplishing the desired result. Fig. 19 shows the principle applied to a toothed clutch set between miter gears, for reversing a grinding machine. When th stop-rod A is shifted endwise it moves the lever B over, and the left-hand end of B throws the clutch into mesh. Simultaneously the plunger C moves outward under the action of the coiled spring, and its beveled end locks with the beveled end of the short extension on B, thus forcing the clutch positively into full engagement, to fit 16 No. 112 STOPS, TRIPS AND LOCKING DEVICES Another example of it there until reversal again occurs. the spring plunger arrangement is illustrated in Fig. 20. This design is taken from the clutch : reversing mechanism of a special gearThe locking is effected by a roller A mounted in a stud or cutter. plunger, and forced outward by a spiral spring contained in the liolder. As the lever B is thrown over by the long lever pivoted to and holding Fig. 20. Spring Plunger applied to Clutch-reversing Mechanism the roller is moved from the ing lever B in position. it, flat face a to the face 6, thus retain- Another method, see Pig. 21, utilizes the bent end of a flat spring A to lock the beveled end of a lever in its two positions. This example taken from a shaping machine, in which the dogs B, bolted to the T-slot in the top of the ram, encounter the trip lever G and throw it over, thus actuating the two connecting levers which move the is lever D, the latter sliding the rod which throws in the friction clutch TRIPS AND REVERSING MECHANISMS 17 inside the belt pulleys. E is a wedge, adjusted in either direction by the screw and knurled nut, by which fine adjustments in length of stroke are obtained while the machine is running. In cases where a clutch is thrown over by the part rotation of a may be utilized in connection with the locking as spindle, the latter Nachinery,N.Y. Fig. 21. Spring Locking Arrangement for the Shaper-reversing Mechanism which shows a mechanism for a milling machine table. situated at A, which catches in the stud inserted in the spindle below, and retains the latter in position. The part rotation of the spindle is effected through a plunger rack B, meshing with the in Fig. 22, A plunger is Machinery, ff. Fig. 22. T. Locking Mechanism for Clutch for Milling Machine Feed-screw teeth cut on the spindle, and forced downwards by the bevel-edged dog C on the edge of the table. D is the toothed clutch thrown into gear by the movement of the spindle, thus throwing the table feed- screw into action. Worm trips are very much in favor on account of their simplicity and their instantaneous effect. The box containing the worm is simply released and falls by the action of gravity, instantly disengaging the No. 112 18 STOPS, TRIPS teeth from those of the wheel. AND LOCKING DEVICES Two examples of this mode of action which the end of a lever A is struck by the downcoming collar or rod on the spindle sleeve, raising the other end of the lever, which is formed as a trigger, and releasing the handle B, which is clamped to the worm-box, pivoted at point a. The worm-box and handle turn on the axis passing through a, and thus the worm is allowed to fall away from its will suffice. Fig. 23 is a trip applied to an upright drill, in Machinery, N.T. Fig. 23. Trigger Trip for Drop Worm-box The striking of the lever A is generally accomplished by an adjustable collar, clamped at any desired position on the spindle sleeve, or by a rod, as in Fig. 24, held in a stud projecting out from the sleeve. gear. mawhich drops the worm from engagement with the gear that turns the table screw. So long as the latch A remains in the position shown, maintained by the spring plunger B, the shoulder cut in it retains the end of the worm-shaft bearing in place, but when dog (7 Fig. 25 is a drop latch fitted to the table of a vertical milling chine, TRIPS AND REVERSING MECHANISMS 19 on the under side of the table comes against the short end of A, the latter is tilted, and the worm drops. With regard to belt-shifting mechanisms, the difficulty of producing the necessary amount of belt travel with a small amount of stop lever movement is overcome by magnifying the effect by a series of long belt levers. The operating tappet mechanism is comparatively simple, comprising in general a striking dog A, Fig. 26, which knocks over the lever B, connected by other levers with the beltshifting mechanism. The return of the lever B is produced by the other dog or tappet (7, the catch of which can be tipped up, out of the way. The fitting of trip motions to disks is adopted in various ways, a stop-block being usually bolted to the disk so that at a predetermined Machinery,!?.?. Fig. 24. Trip Hod Fitted to Drill Press Sleeve the block actuates the trip gear and throws out a certain Thus in Pig. 31, the worm-wheel has dogs bolted to a T-slot in its face, and these dogs strike a swinging lever A, thus point, movement. imparting a partial rotation to the shaft on which it is keyed, and rack and pinion, a slide which carries a sector disengaged. The spring plunger and roller B either of its two positions, the roller pressing of the two slopes of the beveled end. Another dropping, through a gear that has to be keep the lever A in on one or the other interesting application of the disk trip is illustrated in Fig. 29, which shows the end of a boring mill cross-rail. When the clutch C is in gear, the feed-screw A is turned by a gear B, operated from other spur gears not shown. A worm-wheel Z>, with a T-slot in its face for carrying a dog E, is driven by a worm on the extension of the screw A. When, therefore, the clutch is in mesh, the wheel D continues to rotate until E comes in contact with the beveled end of the trip lever F, and 20 No. 112 STOPS, TRIPS AND LOCKING DEVICES TRIPS AND REVERSING MECHANISMS 21 the latter pushed over, disengaging the clutch, and stopping the rotation of A. Dog E is set at any required position on the circle to trip the feed at the desired position of the cross-slide on the rail. Another variation of the same idea is shown in Fig. 28, illustrating a feeding device for a gear-cutter. A slotted lever A is rocked to and fro, and hy means of the pawls a gives intermittent turning movements is Fig. 27. Combined Reversing and Feeding Mechanism for Grinding Machine This continues until the dog & comes in the which are then thrust out of engagement with B, thus to the ratchet wheel B. way of the pawls, stopping the feed. In certain cases the feed is engaged automatically at the same time that the reversal occurs, as in planers. An interesting device, applied specially to the Richards' side planing machines made by Geo. Richards & Co., Ltd., Manchester, is used for giving the down feed to the toolbox that is situated at the end of the long arm. When the saddle A, Fig. 30, travels along the bed B, propelled by its screw turned by belt 22 No. 112 STOPS, TRIPS AND LOCKING DEVICES MacMnery,N. Y. Fig. 28. Fig. 29. Ratchet Feed Trip for Gear-cutter Trip of the Disk Type used on a Boring Mill TRIPS AND REVERSING MECHANISMS- , 23 No. 112 24 STOPS, TRIPS AND LOCKING DEVICES pulleys with open and crossed belts, a pair of horns a, bolted to A, strike dogs &, mounted on a rod c, which by its longitudinal movement actuates the belt-shifting mechanism and produces the reversals, as in an ordinary planer. But the rod c is also given a twisting movement, in the following manner: Within the bearing d is a bushing, having cam grooves cut in its walls as shown in the enlarged detail, these grooves receiving rollers on the ends of a pin that passes through the rod c. therefore c is slid endwise it must twist the rod, because the bushing cannot turn. Another rod e, through the medium of miter When gears, imparts the down feed to the screw of the tool-box through a ratchet gear. The combined reversal and feed is also applied to grinding machines, wheel a slight amount after each pass or stroke. One illustration of this class of mechanism as fitted to the Birch grinders is seen in Pig. 27. The rocking of the lever A in alternate directions when struck by the table dogs has the effect of rocking B up and down, and causing the spring-maintained pawl C to feed the disk, on the periphery of which fine ratchet teeth are cut. Hand adjustment is obtained by the small lever seen near the top. to feed the CHAPTER II CLAMPING AND LOCKING DEVICES APPLIED TO MACHINE TOOLS Devices for clamping and locking various parts are found on pracmachine tools, and the different methods used afford a very interesting study. In considering this subject we disregard permanent fastenings that is those which are not released and tightened as part tically all Machinery. AV Fig. 32. for Set-screw with Shoe Clamping Sleeve Fig. 33. Screw Recessed into Strip for Clamping Slide machine and take into account only those devices which are expressly designed to permit of more or less rapid loosening and tightening, to allow adjustments. There are a great many conditions under which these devices are required, and the parof the operation of the Machinery. N.7. Fig. 34, Screw and Notched Shoe for Clamping Slide ticular type adopted may vary widely in character; a design that is exactly suited to one case may be utterly unsuitable for another. For instance, the pressure from the point or end of a screw is sufficient for No. 112 26 AND LOCKING DEVICES STOPS, TRIPS holding some parts, but in other cases this would be an unsatisfactory method to adopt. Again, friction may be ample to hold a certain part, while in another case a positive device is necessary. The and locking which will be made Clamping produces a decided pressure, suffi- distinction between clamping in the following is this: Machineru. N. Clamping: Screw with Fig. 35. End entering- T. Groove for Clamping Stud machine to resist the shocks or vibration tending to shift it, while locking is only a method of temporarily holding a piece in position, by means of a plunger or other medium, sumcient to enable a part of a \ Machinery, N. Y, Fig. 36. Full-down Bearing Clamping Screw with Action for Clamping Fig. 37. Bolt and Handle for Clamping Drill Head it, but without giving a powerful clamping or squeezing locking device, therefore, might not be powerful enough to act as a clamping device, so that these functions must be regarded as cient to retain action. distinct locked, A from each other. when we ought As a matter of course we say that a slide is to say that it is clamped, because the parts are drawn together powerfully, and not merely prevented from shifting by a pin or other means. As a general rule it may be said that locking CLAMPING AND LOCKING DEVICES 27 holds a machine part in a definite position, or in one of a series of positions previously known, by means of holes, slots, or grooves, which determine these positions; but a part may be clamped at any location, Machinery. S. Fig. 38. Showing Use of Bolts and Strap for Clamping with or without the use of graduations or other means to determine the setting. In some cases, although these are not very common, locking and clamping are combined, the latter supplementing and assisting the former. Machinery,!?. Fig. 39. r Machinery, A Y Clamping Screw Located on One Side Fig. 40. . Y Clamping Device for Drill Saddle The following selection of typical devices, representative of American, English, and German practice, will serve to illustrate the principles A large number of other examples, of clamping and locking devices. which might be shown, are but modifications of those here selected. Clamping- Devices Dealing first with clamping, the simplest example is a set-screw pressing upon the portion that has to be secured. This is a cheap de- 28 No. 112 STOPS, TRIPS AND LOCKING DEVICES open to objections. On a flat surface it is efficient, but the too local, and this construction is not adapted to withstand heavy strains without slipping. Moreover it has the bad effect of forcing the parts away from each other when screwed up, so that a fruitful vice, but pressure is is source of vibration is introduced, whereas other and better methods of clamping pull the parts together and act as clamps in the true sense of the word. Usually the pressure of a set-screw point is objectionable, * Machinery, N. Y. Fig. 41, Clamp for Grinding Swivel Table Macnine Machinery, Fig. A", Clamping Arrangement for V-slide 42. and a soft pad or shoe is employed to avoid the marring effect otherwise met with. This pad or shoe may be shaped to correspond with the form of the surface against which it bears. Fig. 32 is an example of a set-screw in an awkward situation, this example being taken from one of the Seller's tool-grinders; the screw passes through a bushing, and presses upon a pad shaped to fit the outside of the cylindrical In some cases the shoe or pad may be notched out to press sleeve. against the V of a slide, as in Fig. 34, for locking purposes. This ex- CLAMPING AND LOCKING DEVICES 29 ample is taken from a cutter-grinder. The necessity for a shoe is sometimes avoided by sinking the end of the .screw into the metal, as in Fig. 33, which shows a gib clamp for a milling machine slide. In the case of a circular part, Pig. 35, a groove is turned for the locking screw to enter, this construction also preventing endwise motion of the pin to be locked. The function of the pin is to actuate a clutch for a drill- Fig. 43. Clamping Strip with Springs for Kaising the Strip when Released ing machine head. Sometimes the groove is arranged so that the screw draws the piece tightly downward to a bearing, as shown in Pig. 36. There are numerous instances where ordinary bolts are employed for clamping purposes; some special form of clamp or strap is often used in this connection, in order to utilize the pressure to the best advantage. Thus in the work-spindle slide of a gear-cutter, Fig. 38, four bolts are Tig, 44. Clamping Action on Opposite Sides of Swivel-block employed, and a dished clamping plate is used to clear the nut at the back of the slide. When rapid manipulation without using a spanner is desirable, a handle takes the place of the hexagon nut, as on the sensitive drill shown in Fig. 37. Another case where the clamping screw is set to one side, owing to the presence of a central hole, is seen in Fig. 39; a fillister-head screw retains the plate in position on one side, and the tightening of the handle clamps the slide against the face of the casting. This detail is taken from a cutter-grinding machine. After some time, a clamping handle will assume a position which renders its proper operation difficult, and provision may be made to compensate for wear to prevent this trouble. Thus, in Pig. 40, the handle turning the screw which pulls up the clamping block is secured by a set-screw. By losening the latter, the handle can be readjusted into the most convenient position. This particular example represents the clamp for the saddle of a radial drill. No. 112 30 STOPS, TRIPS AND LOCKING DEVICES Fig. 41 illustrates the table clamp of a grinding machine, which permits of the swiveling motion for angular grinding. This design differs from the previous instance in that the bolt is adjustable in its slot tj allow for the radial movement of the table. Another specimen of clamping with a block drawn up by a bolt and handle is shown in Fig. Machinery, N.Y. Fig. 45. 42, and is Clamping with Bolt and Bushing Machinery. JV. Y. Fig. 46. Clamping Plate for Edge of Milling Machine Table used for a milling machine slide. The threaded end of the bolt is tapped into the block, and the latter presses against the beveled edge of the slide. Another variation of this type of device is shown in Fig. 43, illustrating the outer bearing for a gear-cutting spindle. Machinery, N. Fig. 47. Clamping Arrange- ment based on the Action of the Metal Spring Fig. 48. Clamping Bolt for Poppet This F. or Tailstock Spindle must be adjusted endwise; by loosening the two set-screws, the is raised by the coiled springs, and the bearing is free slide. Under certain conditions it is necessary to have a perfectly spindle clamping strip to balanced clamping effort, as, for example, in dividing heads. An instance of this is illustrated in Fig. 44. The swivel-block has beveled edges turned at each side, and the correspondingly shaped blocks are drawn together simultaneously by the tightening of the nut the clamps are guided in the solid metal, so that distortion is prevented. A similar ; CLAMPING AND LOCKING DEVICES 31 employed in many classes of clamping devices for cylindriprinciple cal parts, such as the spindle in Fig. 45, which is secured by the pressure of the bolt head and the bushing, suitably formed to fit the is and drawn down upon it by tightening the nut. The spindle is not marred, and there is no need of weakening the bearing by splitting it for the purpose of clamping. spindle, Machinery, X.T. Fig. 49. Method of Clamping with a Split Bracket Fig. 50. Clamping a Partially Split Bracket to a Column Three other types of clamping devices are shown in Figs. 46, 47 and being a plate forced against the side of a milling machine table, this being an alternative construction to that in Fig. 33. Fig. 47 48, the first Fig. 51. Sleeve Split at Ends for Clamping Fig. 52. Example of Wedge Clamping a form that is possible in only a few cases, the mental being left solid, except for a split or slot, and the clamping effected by its springing is 32 No. 112 STOPS, TRIPS AND LOCKING DEVICES action only. This detail shows the method of attaching a milling machine brace to the knee. Fig. 48 shows a clamping arrangement for a poppet or tailstock spindle, which also serves the purpose of keeping the spindle from turning. One of the most popular methods of clamping is by the split lug, boss Machinery, N.Y. Fig. 53. Clamping Two Bearings simultaneously drawn together by a screw or screws. This provides for a very powerful grip. There are so many examples of this device that it is only possible to show a few types. In small lugs, fillister head screws are suitable for the drawing-together action, but a bolt is better for cr collar, Machinery, N.Y. Fig. 54. Clamping Handle carried out to Edge of Table for Convenience of Operation large parts, as in Fig. 49, which shows the bracket of a cutter-grinder clamped on its pillar. It is not always necessary to carry the split right through the boss; it may pass only partly through, as in Fig. 50. The bolt in this case is held by a set-screw, so that it may be turned partly around to bring the clamping handle into the most convenient Fig. position, this constituting a variation of the method in Fig. 40. 51 is another instance of partial splitting of a sleeve of a radial drill arm. An interesting type of such a method of clamping is found in the Brown & Sharpe milling machine arm; the two tightening screws are CLAMPING AND LOCKING DEVICES 33 s situate<J at the opposite ends of the frame, but are coupled together by a rack-bar which causes the two screws to turn simultaneously. It is, therefore, necessary to turn one screw only, as indicated in Fig. 53. The tightening nut or lever for a split clamp is usually placed close to the boss, but in some cases it may be necessary to vary the position machinery, N.T. Fig. 55. Wedge Action Clamp for Grinder Tailstock for convenience of manipulation. Thus in the drilling machine table, Fig. 54, the screw is prolonged into a long spindle, thus bringing the clamping handle to the front of the table, where the operator can reach without effort or straining. Fig. 60 illustrates a split clamp which does not act in the usual manner, but serves to draw two beveled sur- it Machinery, y. T. Fig. 56. Knee Long Strip of Hilling for Clamping Machine Fig. 57. Eccentric Clamp for Tailstock faces together (this example being a pillar and sleeve of a radial drill), to prevent rotation. When the clamp is loosened, the sleeve is free to turn on its ball-race. Wedge action is utilized for clamping, in numerous cases, instead of direct screw pressure, and is often more suitable for certain purposes. Fig. 52 is representative of several such designs, this example being the clamp for a grinder tailstock; the action is like that of a cotter. A 34 No. 112 STOPS, TRIPS AND LOCKING DEVICES CLAMPING AND LOCKING DEVICES 35 similar principle is employed in Fig. 55 where the overhanging arm of a special grinding machine is held by the forcing upward of a block through the screwing in of a tapered plug. The groove in the arm also prevents the latter from twisting. Fig. 56 shows the principle of a clamping arrangement used by Messrs. Alfred Herbert, Ltd., on their milling machines. The object is Fig. 61. Clamping Four Spindles simultaneously clamp the entire length of the knee, instead of clamping at one wedge strip being forced downward by turning the handle, which causes the pinion A to rotate and force the strip along. Another instance of wedge action combined with levers, is seen in Fig. 58, which shows the Whitcomb-Blaisdell planer cross-rail fastening. to location only, the Machinery, X.Y. Fig. 62. Eccentric Action Clamping Device used on Chucking Lathe the handle in the disk A is pulled over, it draws the strip and wedge B along, and the latter presses against the roller C, which is mounted on the pivot pin of the levers D. These levers are forced outward, and as they pivot on the screws near their ends, they are caused When and thus pull the cross-rail F\g. 61 shows a multiple multiple dividing centers. The object to press against the inside of the uprights, tightly against the faces of the housings. clamping arrangement, used on is to bind the four spindles simultaneously. When the right- and left- 36 No. 112 STOPS, TRIPS AND LOCKING DEVICES is turned, it draws the two wedges together, and these push the blocks A upward, thus binding the spindles. Eccentric action is also employed extensively, and has the advantage of being more rapid and convenient for some kinds of clamping than a screw or wedge. This action is particularly handy when the clamping and unclamping is very frequent. An eccentric device applied to a The nuts at the bottom of lathe tail-stock is illustrated in Fig. 57. the clamping plate allow for adjustment to make the eccentric act at the proper position of the handle. A modified form of the same type is seen in Fig. 59, which is used for a bench lathe, while an arrangement for the turret saddle of a chucking lathe is shown in Fig. 62. The clamping plate here is designed to pull the saddle over against the edge A of the bed, so that a constant alignment is preserved. The tightening hand screw which abut against studs, screwed into the face adjacent to the boss, and arrest the lever at definite positions. An instance of duplex clamping, applied to the head of a vertical milling lever has stop lugs, Machinery, N. Fig. 63. Y. Eccentric Clamping Arrangement for Vertical Milling Machine Head shown in Fig. 63. The clamping rod passing through the machine, casting has slightly eccentric ends, and these force the lugs upon them is in an outward direction when the lever is pulled, thus drawing the plates or clamping strips against the back edges of the projecting ways of the column. Adjustment is made by means of the threaded ends and the nuts. Provision has occasionally to be included for permitting a pivoting or "throw-back" action in connection with clamping. Very frequently a pivoted eye-bolt meets the requirements, or alternatively a loop or strap fitted, as shown in Fig. 64, to a hinged steady-rest. A different method is to employ bolts in T-slots, Fig. 65, the two marked A being used to hold the bracket down, for steadying the arbor support of a CLAMPING AND LOCKING DEVICES 37 gear-cutterS The bracket is hinged on the pivot-pin in the plate B, and the latter remains clamped in position by its two bolts. When the bracket has to be thrown back, it is only necessary to slacken the nuts Another point with reference to that power is sometimes gained by using gears for effecting a specially tight grip. There is one type of lathe tailstock in which the clamping bolt is turned by a spur gear actuated by a pinion, on the shaft of which the spanner is placed, thus giving a very powerful grip for high-speed work. A. and slide the bolts out of the slots. clamping is Locking- Devices Taking up now the consideration of locking devices, it should be mentioned that these may be classified as positive locks and friction locks, the latter being obviously unsatisfactory in many cases where the risk of any slip would be detrimental. The simplest lock, perhaps, is that used for the back-gears of a lathe or other machine, where a Fig. 65. Clamping Device for a Bracket belt is slid into a slot to encounter a projection on the cone pulley. The pin may also be pushed endwise into a hole, the relative positions and out-of-gear being controlled by a spring. This kind of device employed to lock the pulleys of grinding heads when dead-cent3r work is being done. Fig. 66 represents a lock adopted on a high-speed of in- is also lathe, the locking bolt being tapered to fit in the slot in the adjacent A gear, the object being to prevent back-lash. typical positive lock is shown in Fig. 67, this example being the pin for securing the eccentric spindle of a back-gear. The pin may be straight or parallel, as shown, but more frequently it is tapered. Slides or other parts are frequently locked by tapered pins. 38 No. 112 STOPS, TRIPS AND LOCKING DEVICES Machinery, Fig, 66. JV. F. Locking Pin for Lathe-head Gears Mavhtnery.N.Y. Fig. 67. Eccentric Spindle Locking Pin Fig. Locking Arrangement for Indexing Lever 68. CLAMPING AND LOCKING DEVICES 39 locking device employed on the open-spindle turret lathes Fig. 69 is of Messrs. John Lang & Sons, to hold the spindle while the chuck on When the the nose is being tightened or loosened with a spanner. lock is thrown downward, the spindle is free to rotate. Two other positive locks are illustrated in Figs. 70 and 73, one for a turret lathe of the type used largely in England, the other for a central-hole type of Machinery, Fig. 69. Lock for Open Spindle of John Lang & _V.F, Sons Turret Lathe In both cases a tapered part enters slots in the periphery of turret. the indexing disks. The wedge strip beside the plunger in Fig. 73 takes up play due to wear. Positive locks are also seen in Figs. 68 and 72. In Fig. 68 a disk on the body of a sleeve has notches, into any one of which the pivoted catch drops, under the action of a coiled spring, thus holding the sleeve Machinery, y. T. Pig. 70. Locking Turret with External Lever one position. Fig. 72 shows a quick-withdrawing device for screwcutting; when the catch A drops into engagement with the toothed disk B the rotation of the latter has the effect of turning the quick-pitched in C. The spring plunger D in the lever which carries A, locks the latter in either the "in" or "out" position, according to whether the screw 40 No. 112 STOPS, TRIPS AND LOCKING DEVICES SJ d CLAMPING AND LOCKING DEVICES 41 plunger point-slips into either the one or the other of the countersinks in the inner end of A. The spring plunger is a familiar locking device, and is found in varied forms, usually embodying a pointed or tapered plunger which obviates back-lash. A common instance is that shown in Fig. 74 used Machinery.!?. T. Fig. 73. Plunger Lock for Turret for a speed- or feed-change lever. The plunger is contained within the handle, and its point slips into any one of the countersinks in the quadrant The arrangement may also be as in Fig. 71, with a pull-back device for each plunger, as the latter in this case enter more deeply Machinery, X.T. Tig. 74. Common Type for of Spring Plunger Locking Lever Plunger Locking ATrangement for Gear Box Fig. 75. An alternative construction is shown in Fig. where the block which moves or slides the spur gears endwise is locked by a tapered sleeve entering any one of four tapered recesses in into their locking holes. 75, the locking plate. A spring inside the sleeve keeps it in position. Fig. 76 illustrates another method of withdrawing a plunger, this method being used on the familiar Hendey-Norton change-gear device, in which No. 112 42 STOPS, TRIPS AND LOCKING DEVICES the act of grasping the handle firmly withdraws the plunger, ready for the movement to another hole. Still another method, employed on a milling machine dividing head is represented in Fig. 79; the locking plunger in this example is pulled back by a rack and pinion device, and Machinery, N.Y. Fig. 76. Withdrawing and Locking Device on Change-gear Box Fig. 77. Spring- Lock for Back-gear Lever is itself locked by drawing it backward until the pin end slips into the slot in a bushing as shown. Fig. 78 shows a different construction, also for a dividing head, the plunger A has only a pull-back action, without a positive lock, while the other plunger B is provided with a pin which slips into a sort of the pinion sleeve near its Machinery, N. Fig. 78. Locking Plungers for Index Plate V. and Lever bayonet catch, and prevents the plunger from moving forward under the action of the spring. The locking plunger in Fig. 80 (for coupling in the back-gears of a vertical milling machine), is held out of position by the pin A, but a quarter turn of the plunger allows this pin to slip into a groove inside the bore and thus let the plunger into any one of Finally, the Brown and Sharpe back-gear an ingenious method of retaining automatically the holes in the disk below. lock, Fig. 77, represents the ball ends of a lever in position. The succeeding illustrations are those of friction locking devices. CLAMPING AND LOCKING, DEVJCES Fig. 81 might be classed as a clamping 43 \'.' device, but as its only pur- to allow locking in different positions, it should logically be classed in the latter category. The split handle or lever is employed pose is Machinery, F.Y. Tig. 79. Withdrawing and Locking Fig. Device for Spring Plunger to 80. Locking Plunger with Locking Pin work the may have tion, it cross-slide of a turret lathe. In order that the operator the handle in the most convenient and least fatiguing posi- is adjustable around the pin on which it is mounted, by Machinery, Fig. 81. Cross-slide Lever with Split Hub Jf.T. for Locking in Various Positions An alternative method is to taper the inside of the lever, as in Pig. 82, to match the outside of the slotted levers shown, and force the two together by a nut. This constitutes a friction clutch, and is an idea that is found in many locking devices, especially for locking gears and other parts together ternsimply loosening the binding screw. 44 'ill'- -STOPS, .TRIPS AND LOCKING DEVICES Other arrangements porarily, and for micrometer and similar devices. for micrometer dials are shown in Figs. 83 and 84, for locking the dials at zero when desired. Fig. 83 has a small bolt tightened by a knurled-head nut, the head of the bolt lying in a circular T-slot in Machinery, N. Y. Fig. 82. Cross-slide Lever with Friction Lock tlie dial. When the nut is screwed up, t^v dial is locked to the handwheel and turns with it. In Fig. 84 the ^oint of the central threaded plunger forces a small block outward against the bore of the dial, and locks the latter. Machinery. N. Fig. 83. T-bolt Friction Lock for Micrometer Dial Fig. 84. Y. Pin Friction Lock for Micrometer Dial Ratchets are occasionally utilized for locking purposes, one instance being in wire-feeds, where the feeding dog is held on its supporting rod by a pawl entering into the teeth of the ratchet bar. UNIVERSITY OF CALIFORNIA LIBRARY, BERKELEY THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW Books not returned on time are subject to a fine of 50c per volume after the third day overdue, increasing $1.00 per volume after the sixth day. Books not in to demand may be renewed if application is made before expiration of loan period. JUL 13 519725 fiEC'DLD 3 72 >4 PM 91 20m-lV20 53944 UNIVERSITY OF CAUFORNIA LIBRARY MACHINERY'S DATA SHEET SERIES ' MACHINERY'S Data Sheet Books include the well-known series of Data Sheets originated by MACHINERY, and issued monthly as supplements to the publication; Reof these Data Sheets over 500 have been published, and 6,000,000 copies sold. vised and greatly amplified, they are now presented in book form, kindred subThe price of each book is 25 cents (one shilling) jects being grouped together. delivered anywhere in the world. CONTENTS OP DATA SHEET BOOKS No. 1. Screw Threads. United States, Whitworth, Sharp V- and British Association Threads; Briggs Pipe Thread; Oil Well Casing Gages; Fire Hose Connections; Acme, Worm and Metric Threads; Machine, Wood, Lag Screw, and Carriage Bolt Threads, etc. No. 2. Screws, Bolts and Nuts. Fillister-head, Headless, Collar-head and Hexagon-head Screws; Standard and Special Nuts: T-nuts, T-holts and Washers; Thumb Screws and Nuts; Machine Screw Heads; Wood Screws; Tap Drills. No. 3. Taps and Dies. Hand, Machine, Tapper and Machine Screw Taps; Taper Die Taps; Sellers Hobs- Screw Machine Taps; Straight and Taper Boiler Taps; Stay-bolt, Washout, and Patch-bolt Taps; Pipe Taps and Hobs; Threading Dies. No. 4. Reamers, Sockets, Drills and Milling Hand Reamers; Shell Reamers and ArCutters. bors; Pipe Reamers; Taper Pins and Reamers; Brown & Sharpe, Morse and Jarno Taper Sockets and Reamers; Drills; Wire Cages; Milling Cutters; Setting Angles for Milling Teeth in End Mills and Angular Cutters, etc. No. 5. Spur Gearing. Diametral and Circular Pitch; Dimensions of Spur Gears; Tables of Pitch Diameters; Odontograph Tables; Rolling Mill Gearing; Strength of Spur Gears; Horsepower Transmitted by Cast-iron and Rawhide Pinions; Design of Spur Gears; Epicydie Gearing. No. 6. Bevel, Spiral and Worm Gearing. Rules and Formulas for Bevel Gears; Strength of Bevel Gears; Design of Bevl Gears: Rules and Formulas for Spiral Gears: Diagram for Cutlers for Spiral Gears; Rules and Formulas for Worm Gearing, etc. No. 7. Shafting, Keys and Keyways. Horsepower of Shafting; Strength of Shafting; Forcing, Driving, Shrinking and RuT>"ing Fits; Woodruff Keys; Standard Keys; Gib Keys; Milling Keyways; Duplex Keys. No. 8. Bearings, Couplings, Clutches, Crane Chain and Hooks. Pillow Blocks; Babbitted Bearings; Ball and Roller Bearings; Clamp Couplings; Flange Couplings; Tooth Clutches; Crab Couplings; Cone Clutches; Universal Joints; Crane Chain; Crane Hooks; Drum Scores. No. 9. Springs, Slides and Machine Details. Formulas and Tables for Spring Calculations; Machine Slides; Machine Handles and Levers: Collars; Hand Wheels; Pins and Cotters; Turn-buckles. No. 10. Motor Drive, Speeds and Feeds, Change Gearing, and Boring Bars. Power required for Machine Tools: Cutting Speeds and Feeds for Carbon and High-speed Steel; Screw Machine Speeds and Feeds; Heat Treatment of High-speed Steel Tools; Taper Turning; Change Gearing for the Lathe; Boring Bars and Tools. No. 11. Milling Machine Indexing, Clamping Devices and Planer Jacks. Tables for Milling Machine Indexing; Change Gears for Milling Spirals; Angles for setting Indexing Head when Milling Clutches; Jig Clamping Devices. No. 12. Pipe and Pipe Fittings. Pipe Threads and Gages; Cast-iron Fittings; Bronze Fittings; Pipe Flanges; Pipe Pen-Is; Pipe Clamps and Hangers. No. 13. Boilers and C.iimneys. Flue Spacing and Bracing for Boilers; Strength of Boiler Joints; Itivetiug; Boiler Setting; Chimneys. No. 14. Locomotive and Railway Data. Locomotive Boilers; Bearing Pressures for Locomotive Journals; Locomotive Classifications; Rail Sections; Frogs, Switches and Cross-overs; Tires; Tractive Force; Inertia of Trains; Brake Levers. No. 15. Steam and Gas Engines. Saturated Steam; Steam Pipe Sizes; Steam Engine Design; Volume of Cylinders; Stufling Boxes; Setting Corliss Engine Valve Gears; Condenser and Air Pump Data: Horsepower of Gasoline Engines; Automobile Engine Crankshafts, etc. No. 16. Mathematical Tables. Squares of Mixed Numbers; Functions of Fractions; Circumference and Diameters of Circles; Tables for Spacing off Circles; Solution of Triangles; Formulas for Solving Regular Polygons; Geometrical Progression, etc. Mechanics and Strength of Materials. Work; Knergy: Centrifugal Force; Center of GravMotion; Friction; Pendulum; Falling Bodies; No. 17. ity; Strength of Materials; Strength of Flat Plates; Strength of Thick Cylinders, etc. No. 18. Beam Formulas and Structural Design. Beam Formulas; Sectional Moduli of Si i-uctural Shapes: Meam Charts; Net Areas of S-ructural Angles; 'Jivet Spacing; Splices for Channels and I- beams; Stresses in No, 19. Belt, sions of Pulleys: of Belting; Belt Roof Trusses, etc. Rope and Chain Drives. DimenWeights of Pulleys; Horsepower Velocity: Angular Belt Drives; Horsepower transmitted by Ropes; Sheaves for Rope Drive: Bending Stresses in Wire Ropes; Sprockets for Link Chains; Formulas and Tables Driving Chain. No. 20. Wiring Diagrams, Heating and Ventilaand Miscellaneous Tables. Typical Motor tion, Wiring Diagrams; Resistance of Round Copper Wire; Current Densities for Various Contacts and Materials; Centrifugal Fan and Blower Capacities; Hot Water Main Capacities; Decimal EquivaMetric Conversion Tables. Weights and lents. Specific Gravity of Metals, Drafting-room Confor ventions, etc. MACHINERY, the leading journal in the machine-building field, the originator of the 25-cent Reference and Data Books. Published monthly. Subscription, $2.00 yearly. Foreign subscription, $3.00. The Industrial Press, Publishers of MACHINERY, New York City, 49-55 Lafayette Street, U 1 . S. A.
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