Largeimage(96 kB).Fig. 494Fig. 494.
Largeimage(96 kB).
Fig. 494.
Fig. 495Fig. 495.
Fig. 495.
Fig. 494is a sectional side elevation of the headstock;a a′represents the headstock carrying the bearing boxesbandb′, which are capable of bore closure so as to be made to accurately fit the spindlesby the construction of the front bearingb, being more clearly shown inFig. 495;bis of composition brass, its external diameter being coned to fit the taper hole in the head; it is split through longitudinally, and is threaded at each end to receive the ring nutscandc′. Ifcbe loosened from contact with the radial face ofa, thenc′may be screwed up, drawingbthrough the coned hole ina, and, therefore, causing its bore to close upons.
Fig. 496Fig. 496.
Fig. 496.
At the other end ofs,Fig. 496,c′′is a ring nut for drawing the journal boxb′througha′to adjust the bore ofb′to fit the journal ofs, space to admit the passage ofb′being provided ate.dis a box nut serving to withdrawb′or to secure it firmly in its adjusted position, and also to carry the end adjusting stepe.fis a check nut to lockein its adjusted position.
The method of preventing end motion tosis more clearly shown inFig. 496, in whichhis a steel washer envelopings, having contact with the radial face ofb′and secured in its adjusted position by the check nutsg, hence it preventssfrom moving forward to the right.fis a disk of raw hide let intoe; the latter is threaded indand is squared at the end withinfto admit of the application of a wrench, henceemay be screwed in until it causes contact between the face offand the end ofs, thus preventing its motion to the left. By this construction the whole adjustment laterally ofsis made with the short length fromhtof, hence any difference of expansion (under varying temperature) between the spindle and the heada a′, or between the boxes and the spindles, has no effect towards impairing the end fit ofsin its bearings.
The method of adjusting the bearings to the spindle is as follows:—c′′andc′are slackened back by means of a “spanner wrench” inserted in the holes provided for that purpose.canddare then screwed up, withdrawingbandb′respectively, and leaving the journal fit too easy.c′is then screwed up untilbis closed upon the spindle sufficiently that the belt being loose on the cone pulley, the latter moved by the hand placed upon the smallest step of the cone can just detect that there is contact between the bore ofband the spindle, then, while still moving thecone, turnc′back very slowly and a very little, the object being to relieve the bore ofbfrom pressure againsts.cmay then be screwed up, firmly lockingbin its adjusted position.c′′may then be operated to adjustb′in a similar manner, anddscrewed up to lock it in its adjusted position. Before, however, screwing updit is better to removefand releaseefrom pressure againstf, adjusting the end pressure ofeafterdhas been screwed home againsta′.
To preventbandb′from rotating in the head when the ring nuts are operated, each is provided with a pin,q, groovescandc′permitting of the lateral movement ofbandb′for adjustment. The boxesb,b′admit of being rotated in their sockets inaanda′so as to assume different positions, the pinsqandq′being removable from one to another of a series of holes in the boxesb,b′when it is desired to partly rotate those boxes. The tops of the boxes are provided with oil holes, and the oil ways shown atr,sbeing the oil groove through the head andasimply a stopper to prevent the ingress of dust, &c.
The thread onsatz,Fig. 494, is to receive and drive the face plates, chucks, &c., which are bored and threaded to fit overz. To cause the radial faces of such face plates or chucks to run true, there is provided the plain cylindrical partl, to which the bore in the hub of the face plate or chuck is an accurate fit when the radial face of that hub meets the radial facem.
Referring again toFig. 494,g′is the pinion to drive the back gear whilegreceives motion from the back-gear pinion. The object of the back gear is to reduce the speed of rotation ofsand to enable it to drive a heavier cut, which is accomplished as follows:—g′′is secured within the endkof the cone and is free to rotate with the cone upons; at the other end the cone is secured tom, which is free to rotate uponsso far as its bore is concerned.gis fixed uponsand hence rotates at all times with it; butgmay be locked to or released frommasfollows:—
Ingis a radial slot through which passes a boltiprovided with a cap nuth, inmis an annular groovej. Wheniis lifted its head passes into a recess inm, thenhis screwed up andgis locked tom. This is the position ofiwhen the back gear is not in use, the motion of the cone being communicated tosthroughi. But ifhbe loosened andibe moved inwards towardss, the head ofipasses into the annular groovej, and the cone is free to rotate uponswhile the latter andgremain stationary unless the back gear is put into operation. In this latter case the piniong′rotating with the cone drives the large gear of the back gear and the small pinion of the latter drivesg, whose speed of rotation is reduced by reason of the relative proportions of the gear wheels.
In this case it is obvious that since the pulley rotates upon the spindle it requires lubrication, which is accomplished through the oil hole tubesl.
The means of giving motion to the feed spindle and lead screw are as follows:—n,Fig. 494, is a pinion fast uponsand operating the gearo, which is fast upon the spindlep, having journal bearing in a stem ina′and also atg′′.pdrives the three-stepped coner, which is connected by belt to a similar cone fast upon the independent feed spindle. The seat for the driving gear of the change wheels for the lead screw is onpatv. To provide ample bearing surface forpina′the bush or sleeve shown is employed, but this sleeve also serves to pivot the swing framewwhich carries the studs for the change wheels that go between the wheel onvand that on the lead screw;x yare simply oil holes to lubricatepin its bearings.
To provide a wider range of tool feed than that obtainable by the steps on the feed cones, asr, they are provided at their ends with seats for change wheels, the swing framewcarrying the intermediate wheels for transmitting motion fromvto a similar seat on the cone on the feed spindle.
Largeimage(125 kB).Fig. 497Fig. 497.
Largeimage(125 kB).
Fig. 497.
Fig. 497represents the tailstock (or tailblock as it is sometimes termed), shown in section.arepresents the base which slides upon the raisedVs on the bed and carries the upper partb, in which slides the tail spindlec, which is operated longitudinally by the tail screwd, having journal bearing ine, and threaded through the nutfwhich is fast inc. The hand wheelgis for rotatingd, whose thread operating in the nutf, causescto slide withinbin a direction determined by the direction of rotation ofg. To lockcin its adjusted position the handled nuthis employed in connection with the bolti, which is shown in dotted lines;cis split as shown by the dotted lines atf;jis the dead centre fitting accurately into a conical hole inc. When it is required to removejfromcthe wheelgis operated to withdrawcentirely withinb, and the enddofdmeets the endeofjand forcesjfrom the coned hole inc.
The method of securing the tailstock to the shears or releasing it from the same is as follows. A vertical prolongation ofbaffords atb′′a bearing surface for the nut-handleland washerm.kis a bolt threaded intolpassing throughm,b′′andn, the latter of which it carries.nspans the shears beneath the twoVs on which the tailstock slides. Moving or rather partly rotating the handlelin the necessary direction liftskand causesnto rise, and grip the shears beneath, while the pressure ofmonb′′causesbto gripaand the latter to grip the raisedVs on the shears. Iflbe rotated in the opposite direction it will causento fall, leavingafree to slide along the shears. To preventnfrom partly rotating when free, its ends are shaped to fit loosely between the shears as shown atn.
To give tonsufficient rise and fall to enable it to grip or fall entirely free from the shears with the small amount of rotary motion which the handle-leverlis enabled from its position to have, the following device is provided.mis a washer interposed betweenlandb′′. This washer has upon it steps of different thickness as shown atmandm, the two thicknesses being formed by an incline as shown. The face oflhas, as shown, similar steps; now as shown in the cut the steplon leverlmeets the stepsmof the washer, the handle having receded to the limit of its motion. The boltkthen has fallen to the amount due to unscrewing the threaded or nut end ofl, and also to the amount of the difference of thickness atmand atmof the washer, the platenbeing clear of the lathe-shears. But suppose the handlelbe pulled towards the operator, then the surfacelpassing from a thin section on to a thick one asmof the washer, will lift the boltk, causingnto meet the under surface of the shears, and then the motion oflcontinuing the pressure of the thread will bind or locknto the bed.
The surfacea′inFig. 497affords a shelf or table whereon tools, &c., may be placed instead of lying on the lathe bed, where they may cause or receive damage.
Fig. 498Fig. 498.
Fig. 498.
Fig. 498represents an end view of the tailstock viewed from the dead centre end, the same letters of reference applying to like parts that are shown inFig. 497. The split atfis here shown to be filled with a piece of soft wood which prevents the ingress of dust, &c. Atdis a cup or receptacle for oil,ebeing a stopper, having attached to it a wire pin flattened and of barb shape at the end, the object being to cause the wire to withdraw from the cup a drop of oil to lubricate the dead centre and centre in the work. The proximity ofeto the dead centre makes this a great convenience, while the device uses much less oil than would be used by an oil can.
The method of setting over the upper partbto enable the turning of the diameter of work conical or taper instead of parallel is shown inFig. 498:pandp′are square-headed screws threaded into the walls ofaand meeting at their ends the surface ofb′. Inathere is ataa wide groove or way, and onbthere is atba projection fitting into the wayaso as to guidebwhen it slides acrossa, as it will whenpis unscrewed inaandp′is screwed intoa. This operation is termed setting over the tailstock, and its effect is as follows:—Suppose it be required to turn a piece of work of smaller diameter at the end which runs on the dead centre, then, by operating the screwptowards the front of the lathe (or to the left as shown in the cut) and screwingp′farther intoa, the end ofp′will meet the surface ofb′, causingb′to move over, and the centre of the dead centrej(which is the axis of rotation of the work at that end) will be nearer to the point of the cutting tool. Or suppose the work requires to be turned a taper having its largest diameter at the end running on the dead centre, thenp′would be unscrewed andpscrewed farther intoa, carryingbfarther towards the back of the lathe.
Largeimage(54 kB).Fig. 499Fig. 499.
Largeimage(54 kB).
Fig. 499.
TheVgroovesqandq′fit upon the inner raisedVs shown atv,v′inFig. 499.
Fig. 500Fig. 500.
Fig. 500.
Fig. 499is a side view of the slide rest for holding and traversing the cutting tool.arepresents the carriage resting upon the raisedVs markedv′′andv′′′and prevented from lifting by its own weight, and in front also by the gibasecured toaby the boltband having contact atcwith the shears.acarries atda pivot for the cross slideband atea ball pivot for the cross slide elevating screwc. This screw is threaded through the end ofbso that by operating it that end ofbmay be raised or lowered to adjust the height of the cutting tool point to suit the work. To steadybthere is provided (in addition to the pivots atd) onatwo lugsf, between the vertical surfaces of whichbis a close working fit. The upper surface ofbis provided with aV-slide-wayg, to which is fitted the tool restd(the construction being more clearly shown inFig. 500).
The means for traversingdalong the slidegonbis asfollows:—
A nutiis secured todby the screw boltj, and threaded through the nutiis the cross-feed screwe, which has journal bearing in the piecek, which is screwed into the end face ofb; there is a collar onewhich meets the inner end ofk, and the handlefbeing secured by nut to that end ofeits radial face forms a shoulder atmwhich with the collar prevents any end motion ofe, so that whenfis rotatederotates and winds through the nutiwhich movesdalongb.
An end view ofa,b, anddis shown inFig. 500, in which the letters of reference correspond to those inFig. 499.b′andb′′are the projections that pass intoaand receive the pivoting screwsdandd. To adjust the fit and take up any wear that may ensue on the slideg, onband on the corresponding surface ond, the piecenis provided, being set up by the adjusting screwso.
To adjust the fit and take up the wear at the pivotsdthey are made slightly taper, fitting into correspondingly taper holes inb.
Largeimage(135 kB).Fig. 501Fig. 501.
Largeimage(135 kB).
Fig. 501.
The dotted circlet′, represents a pinion fast upon the cross-feed screw (e,Fig. 499); the similar circlestands′′also represent pinions, the three composing a part of the method of providing an automatic or self-acting cross feed or cross traverse todby rotating it through a gear-wheel motion derived from the rotation of the independent feed spindle, as is described with reference toFig. 501.
minFig. 500represents a cavity or pocket to receive wool, cotton or other elastic or fibrous material to be saturated with oil and thus lubricate the raisedVs while keeping dirt from passing between the rest and theVs. The shape of these pockets is such as to enable them to hold the cotton with a slight degree of pressure against the slides, thus insuring contact between them.
The mechanical devices for giving to the carriage a self-acting traverse in either direction along the bed, so as to feed the tool automatically to its cut, and for giving to the tool rest (d,Fig. 499) traverse motion so as to feed the tool to or from the line of centres along the cross slide, are shown inFig. 501, which presents two views of the feed table or apron. The lower view supposes the feed table to be detached from the carriage and turned around so as to present a side elevation of the mechanism. The upper view is a plan of the same with two pinions (nandn′), omitted.arepresents the part of the lathe carriage shown atainFig. 500. It has two boltspandp′, which secure the aprong,Fig. 501, toa. Athis the independent feed spindle or feed rod operated by belt from the cone pulleyr,Fig. 494, or by a gear on studpatv.his carried in bearings fixed to each end of the lathe shears or bed, both of these bearings being seen inFig. 492.his also provided with a bearing fixed on the feed apron as seen inFig. 501, and is splined as shown ath. Atiis a bracket fast upon the aprongand affording journal bearing toj, which is a bevel pinion having a hub which has journal bearing in the bracketi. The fit of the bearing to the journal is here again adjusted by a split in the bearing with a screw passing through the split and threaded in the lower half (similar to the construction ofdinFig. 493);jis bored to receiveh, and is driven by means of a feather projecting into the splineh. When therefore, the carriageais moved it carries with it the aprong, and this carries the bracketiholding the bevel pinionj, which is ingear with the bevel-wheelk, and therefore operates it whenhhas rotary motion. At the back ofk, and in one piece with it, is a pinionk′, both being carried upon the studl; pivoted upon this same stud is a plate leverm, carrying two pinionsnandn′in gear together, butnonly is in gear withk′, hencek′drivesnandndrivesn′. Now in the position shown neithernorn′is in gear with the gear-wheelo, but either of them may be placed in gear with it by means of the followingconstruction:—
At the upper end ofmthere is provided a handle studm′passing through the slotm′′ing. Screwing up this stud locksmfast by binding it against the surface ofg. Suppose, then,m′to be unscrewed, then if it be moved to the right in the slotm′′,nwill be brought into gear withoand the motion will be transmitted in the direction of the arrows, and screwing upnwould retain the gear in that position. But suppose that instead of movingm′to the right it be moved to the left, thenn′will be brought into gear withoand the direction of rotation ofowill be reversed.
Thus, then,omay be made to remain stationary or to rotate in either direction according to the position ofm′in the slotm′′, and this position may be regulated at will.
The gearocontains in its radial face a conical recess, and upon the same stud or pin (p) upon whichois pivoted, there is fixed the diskp′, which is in one piece with the pinionp′′; the edge ofp′is coned to fit the recess in the wheelo, so that if the studpis operated to force the diskp′into the coned recess inothe motion of wheelowill be communicated to diskp′, by reason of the friction between their two coned surfaces. Or ifpbe operated to force the coned edge of the disk out of contact with the coned bore or recess in gearo, thenowill rotate whilep′andp′′will remain stationary. Suppose the coned surfaces to be brought (by operatingx) into contact andp′to rotate witho, thenp′′being in gear with wheelqwill cause it to rotate. Nowqis fast to the pinionq′, hence it will also rotate, and being in contact with the rack which is fixed along the shears of the lathe and a section of which is shown in the cut, the whole feed table or apron will be made to traverse along the lathe shears.
The direction in which this traverse will take place depends upon the adjusted position ofm′inm′′, or in other words upon whethernorn′be the pinion placed in gear witho. As shown in the cut neither of them is in gear, and motion fromhwould be communicated tonandn′and would there cease; but ifm′be raised in the slotm′′,nwould driveo, and supposingp′to be held too, the motion of all the gears would be as denoted by the arrows, and the lathe carriageawould traverse along the lathe bed in the direction of arrowq′′. But ifn′be made to driveoall the motions would be in the opposite directions. The self-acting feed motion thus described is obviously employed to feed the cutting tool, being too slow in its operation for use to simply move the carriage from one part of the lathe bed to another; means for this purpose or for feeding the carriage and cutting tool by hand are provided as follows:—ris a pinion in gear withqand fast upon the studr′, which is operated by the handler′′. The motion ofr′′passes fromrtoqandq′which is in gear with the rack. Butq′being in gear withp′′the latter also rotates, motion ceasing at this point because the cone onp′is not in contact with the coned recess ino. When, however,p′andoare in contact and in motion, that motion is transmitted tor′′, which cannot then be operated by hand.
It is often necessary when operating the cross feed to lock the carriage upon the lathe bed so that it shall not move and alter the depth of the tool-cut on the radial face of the work. One method of doing this is to throw off the belt that operates the feed spindleh, placenin gear withoandp′in contact witho, so that the transverse feed motion will be in action, and then pull by hand the cone pulley drivingh, thus feeding the tool to its necessary depth of cut. The objection to this method, however, is that when the operator is at the end of the lathe, operating the feedcone by hand he cannot see the tool and can but guess how deep a cut he has put on. To overcome this difficulty a brake is provided to the pinionrasfollows:—
The brake whose handle is shown atvhas a hubv′enveloping the hubr′′′which affords journal bearing to the studr′. In the bore of this hubv′is an eccentric groove, and inr′′′is a pin projecting into the eccentric groove and meeting at its other end the surface of the studr′. When, therefore,vis swung in the required direction (to the left as presented in the cut), the cam groove inv′forcesrinwards, gripping it and preventing it from moving, and hence the movement ofrwhich also locksqandq′.
It remains now to describe the method of giving rotary motion to the cross-feed screwe(Fig. 499) so as to enable it to self-act in either direction.sis a lever pivoted upon the hub ofoand carrying at one end the pinions′′, while at the other end is a studs′passing through a slot ing. The pinions′′is in gear withoand would therefore receive rotary motion from it and communicate such motion to piniont, which in turn imparts rotary motion tot′. Nowt′is fast upon the cross-feed screw as shown inFig. 499and the cross-feed screwein that figure would by reason of the nutiin figure cause the tool restdto traverse along the cross-slide in a direction depending upon the direction of motion oft′, which may be governed asfollows:—
Ifs′be moved to the lefts′′will be out of gear withtand the cross-feed screw may be operated by the handle (f,Fig. 499). Ifs′be in the position shown in cut andm′′also in the position there shown (Fig. 501), operating the feed screw by its handle would cause its piniont′to operatet,s′′, ando; hences′should always be placed to disconnects′′fromtwhen the cross-feed screw is to be operated by hand, ands′operated to connect them only when the self-acting cross feed is to operate. In this way when the cross feed is operated by handt′andtwill be the only gears having motion. It has been shown that the direction of motion ofois governed by the position ofm′, or in other words, is governed by which of the two pinionsnorn′operates, and asodrivess′′its motion, and therefore that oft′, is reversible by operatingm′.
The construction ofs′is as follows:—Within the apron as shown in the side elevation it consists of what may be described as a crank, its pin being att; in the feed table is a slot through which the shaft of the crank passes;sis a handle for operating the crank. By rotatingsthe ends′ofsis caused to swing, the crank journal moving in the slot to accommodate the motion and permitsto swing on its centre.
The device for forcing the cone diskp′into contact with or releasing it fromois as follows:—The studpis fast at the other end inp′and has a collar atb; the face of this collar forms one radial face, and the nutwaffords the other radial face, preventing end motion toxwithout movingpendwise. Ifxbe rotated its thread atx′causes it to move laterally, carryingpwith it, andpbeing fast top′also moves it laterally.p′is maintained from end motion by a groove ato′in which the end of a screwaprojects,ascrewing throughwand into the grooveo′.
The lead screw of a lathe is a screw for operating the lathe carriage when it is desired to cut threads upon the work. It is carried parallel to the lathe shears after the same manner as the independent feed spindle, and is operated by the change wheels shown inFig. 492at the end of the lathe. These wheels are termed change wheels on account of their requiring to be changed for every varying pitch of thread to be cut, so that their relative diameters, or, what is the same thing, their relative number of teeth, shall be such as to give to the lead screw the speed of rotation per lathe revolution necessary to cut upon the work a thread or screw of the required pitch.
Fig. 502Fig. 502.
Fig. 502.
The construction of the bearings which carry the lead screw in the S. W. Putnam’s improved lathe is shown inFig. 502, in whicharepresents the bearing box for the headstock end of the lathe, having the foota′as a base to bolt it to the lathe shears.lrepresents the lead screw, having on one side ofathe collarl′and on the other the nut and washernandn′. The seat for the change wheel that operates the lead screw is atl′′, the stop pinlfitting into a recess in the change wheel so as to form a driving pin to the lead screw. The washern′is provided with a feather fitting into a recess intolso that it shall rotate withland shall prevent the nutnfrom loosening back as it would be otherwise apt to do. End motion tolis therefore prevented by the radial faces ofl′andn′.
At the other end of the lathe there are no collars on the lead screw, hence when it expands or contracts, which it will do throughout its whole length under variations of atmospheric temperature, it is free to pass through the bearing and will not be deflected, bent, or under any tension, as would be the case if there were collars at the ends of both bearings. The amount of this variation under given temperatures depends upon the difference in the coefficients of expansion for the metal of which the lead screw and the lathe shears are composed, the shears being of cast iron while lead screws are sometimes of wrought iron and sometimes of steel.
The bearings at both ends are split, with soft wood placed in the split and a screw to close the split and adjust the bearing bore to fit the journal, in the manner already described with reference to other parts of this lathe.
The construction of the swing frame for carrying the change wheels that go between the driving studv,Fig. 494, and that on the seatl′′,Fig. 502, are asfollows:—
Fig. 503Fig. 503.
Fig. 503.
Fig. 503represents the change wheel swing frame, an edge view of which is partly shown atwinFig. 494.sis a slot narrower atathan atb. Into this slot fit the studs for carrying the change wheels.
By enabling a feed traverse in either direction the lathe carriage may be traversed back (for screw-cutting operations) without the aid of an extra overhead pulley to reverse the direction of rotation of the lathe, but in long screws it is an advantage to have such extra overhead pulley and to so proportion it as to make the lathe rotate quicker backwards than forward, so as to save time in running the carriage back.
Largeimage(59 kB).Fig. 504Fig. 504.
Largeimage(59 kB).
Fig. 504.
The mechanical devices for transmitting motion from the lead screw to the carriage are shown inFig. 504, representing a view from the end and one from the back of the lathe.bis a frame or casting bolted by the boltbto the carriageaof the lathe.cis a disk having a handlec′and having rotary motion from its centre. Instead of being pivoted at its centre, however, it is guided in its rotary motion by fitting atd dinto a cylindrical recess providedinbto receive it.ccontains two slotsdandd′running entirely through it. These slots are not concentric but eccentric to the centre of motion ofc. Through these slots there pass two stud boltseande′shown by dotted lines inFig. 504, and these bolts perform two services: first by reason of the nutsfandf′they holdcto its place inb, and next they screw into and operate the two halvesgandg′of a nut.
Suppose, now, that the handlec′be operated or moved towards arrowe, then the dot atfbeing the centre of its motion and the slotsdandd′gradually receding fromfas their endsgare approached they will causeeto move vertically upward ande′to move vertically downward, a slot inb(which slot is denoted by the dotted linesh) guiding them and permitting this vertical movement.
Sinceeande′carry the two halves of the nut which envelops the lead screwlit is obvious that operatingc′will either close or release the half nuts fromlaccording to which direction it (c′) is moved in.
The screwshandh′screw tightly intob, and the radial faces of their heads are made to have a fair and full bearing against the underside of the shears, so that they serve as back gibs to hold the carriage to the shears and may be operated to adjust the fit or to lock the carriage to the bed if occasion may require. This lathe is made with a simple tool rest as shown in the engravings or with a compound slide rest. In some sizes the rest is held to the carriage by a weight upon a principle to be hereafter described. The bed is made (as is usual) of any length to suit the purposes for which the lathe is to be used.
The next addition to the lathe as it appears in the United States is that of a compound slide rest.