Fig. 505Fig. 505.
Fig. 505.
Fig. 505represents a 28-inch swing lathe by the Ames Manufacturing Company, of Chicopee, Massachusetts. It is provided with the usual self-acting feed motion and also with a compound slide rest. The swing frame for the studs carrying the change wheels for screw cutting here swings upon the end of the lead screw, the same spindle that carries the driving cone for the independent feed rod which is in front of the lathe, also carries the driving gear for the change wheels used for screw cutting.
Fig. 506Fig. 506.
Fig. 506.
Fig. 507Fig. 507.
Fig. 507.
The construction of the compound rest is shown inFigs. 506and507.nis the nut for the cross-feed screw (not shown in the cut) and is carried in the slidea.aand the piecelabove it are virtually in one, since the latter is made separate for convenience of construction and then secured to it firmly by screws.bis made separate fromcalso for convenience of construction and fixed to it by screws;lis provided with a conical circular recess into which the footbofcfits.eis a segment of a circle operated by the set screwfto either grip or releaseb. The boltdsimply serves as a pivot for pieceb c; at its footcis circular and is dividedoff into the degrees of a circle to facilitate setting it to any designated angle.
If, then,fbe unscrewed,cmay be rotated and set to the required angle, in which position screwing upfwill lock it through the medium ofe.gis the feed nut for the upper sliderh, which operates along a slide way provided onc, the upper feed screw having journal bearing atc′.iis the tool post, having a stepped washerj, by means of which the height of the toolkmay be regulated to suit the work.
Suppose, now, that it be required to turn a shaft having a parallel and a taper part; then the carriage may be traversed to turn the parallel part, and the compound slidecmay be set to turn the taper part, while the lower feed screw operating innmay be used to turn radial faces.
The object of makingaandlin two pieces is to enable the boring and insertion ofb, which is done as follows:—The front end oflasl′is planed out, leaving in it a groove equal in diameter and depth to the diameter and depth ofb, so thatbmay be inserted laterally along this groove to its place inl. The segmenteis then inserted and a piece is then fitted in atl′and held fast toaby screws. It is into this piece that the set screwfis threaded.
Various forms of construction are designed for compound rests, but the object in all is to provide an upper sliding piece carrying the tool holder, such sliding piece being capable of being so set and firmly fixed that it will feed the tool at an angle to the line of the lathe centres.
Another and valuable feature of the compound rest is that it affords an excellent method of putting on a very fine cut or of accurately setting the depth of cut to turn to an exact diameter; this is accomplished by setting the upper slide at a slight angle to the line of centres and feeding the tool to the depth of cut by means of the screw operating the upper slide. In this way the amount of feed screw handle motion is increased in proportion to the amount to which the tool point moves towards the line of lathe centres, hence a delicate adjustment of depth of cut may be more easily made.
Suppose, for example, that a cut be started and that it is not quite sufficiently deep, then, while the carriage traverse is still proceeding, the compound rest may be operated to increase the cut depth, or if it be started to have too deep a cut the compound rest may be operated to withdraw the tool and lessen its depth of cut. Or it may be used to feed the tool in sharp corners when the feed traverse is thrown out, or to turn the tops ofcollars or flanges when the tailstock is set over to turn a taper.
It is obvious, however, that comparatively short tapers only can be conveniently turned by a compound slide rest; but most tapers, however, are short.
To turn long tapers the tailstock of the lathe is set over as described with reference to the Putnam lathe, but for boring deep holes the slide rest must either be a compound one or a taper turning former or attachment must be employed.
When, however, the tailstock is set over, the centres in the work are apt to wear out of true and move their location (the causes of which will be hereafter explained).
In addition to this, however, the employment of a taper turning attachment enables the boring of taper holes without the use of a compound slide rest, thus increasing the capacity of the lathe not having a simple or single rest.
Fig. 508Fig. 508.
Fig. 508.
InFig. 508is shown a back view of a Pratt and Whitney weighted lathe having a Slate’s taper turning attachment, the construction of which is as follows:—Upon the back of the lathe shears are three brackets having their upper surfaces parallel with and in the same plane as the surface of the lathe shears. Pivoted to the middle bracket is a bar which has at each end a projection or lug fitting into grooves provided in the end brackets, these grooves being arcs of a circle whose centre is the axis of the pivot in the middle bracket.
The end brackets are provided with handled nuts upon bolts, by which means the bar may be fixed at any adjusted angle to the lathe shears. Upon the upper surface of the bar is a groove or way in which slides a sliding block or die, so that this die in traversing the groove will move in a straight line but at an angle to the lathe bed corresponding to the angle at which the bar may be adjusted. The slide rest upon being connected by a bar or rod to the die or sliding block is therefore made to travel at the same angle to the lathe bed or line of centres as that to which the bar is set. The method of accomplishing this in the lathe, shown inFig. 508, is asfollows:—
Fig. 509Fig. 509.
Fig. 509.
InFig. 509ais the bar pivoted atcupon the centre bracketb;eis the sliding block pivoted to the nut barf. This nut bar carries the cross-feed nut, which in turn carries the feed screw and hence the tool rest. When the nut bar is attached to the sliding block to turn a taper it is free to move endways upon the lower part of the carriage in which it slides, but when the taper attachment is not in use the bar is fastened to the lower part of the carriage by a set screw.
The screw atdis provided to enable an accurate adjustment for the angle of the bara.gandhare screws simply serving to adjust the diameter to which the tool will turn after the manner shown inFig. 588,gbeing for external andhfor internal work.
Fig. 510Fig. 510.
Fig. 510.
When the lathe has a bed of sufficient length to require it, a slide is provided to receive the brackets, which may be adjusted to any required position along the slide, as shown inFig. 510. This is a gibbed instead of a weighted lathe, and the method of attaching the sliding block to the lathe rest is asfollows:—
A separate rod is pivoted to the sliding block. This rod carries at its other end a small cross head which affords general bearing to the end of the cross-feed screw, which has a collar on one side of the cross head and a fixed washer on the other, to prevent any end motion of the said screw.
The cross-feed nut is attached to the traversing cross slide. The other or handle end of the cross-feed screw has simple journal bearing in the slide rest, but no radial faces to prevent end motion, so that one may from the rod attached to the sliding-block traverse the cross-feed slide, which will carry with it the feed screw. As a result, the line of motion of the tool rest is governed by the sliding die, but the diameter to which the tool will turn is determined by the feed screw in the usual manner. When it is not required to use the taper attachment, the rod or spindle is detached from the sliding die and is locked by a clamp, when the rest may be operated in the usual manner.
Fig. 511Fig. 511.
Fig. 511.
Fig. 511represents a compound duplex lathe of a design constructed by Sir Joseph Whitworth, of Manchester, England.The two rests are here operated on the same cross slide by means of a right and left-hand cross-feed screw.
The tool for the back rest is here obviously turned upside down.
The lead screw is engaged at two places by the feed nut, which is in two pieces attached to levers; while at a third point in its circumference it is supported by a bracket, bolted to the lathe bed.
Fig. 512Fig. 512.
Fig. 512.
Fig. 512represents the New Haven Manufacturing Company’s three tool slide rest, for turning shafting. It is provided with a follower rest, in front of which are two cutting tools for the roughing cuts, and behind which is a third tool for the finishing cut. The follower rest receives bushes, bored to the requisite diameter, to leave a finishing cut. The first tool takes the preliminary roughing cut; the second tool turns the shaft down to fit the bush or collar in the follower rest; and, as stated, the last tool finishes the work.
Fig. 513Fig. 513.
Fig. 513.
Fig. 513represents a 44-inch swing lathe, showing an extra and detachable slide rest, bolted on one side of the carriage and intended for turning work of too large a diameter to swing over the slide rest. By means of this extra rest the cutting tool can be held close in the rest, instead of requiring to stand out from the tool-post to a distance equal to the width of the work. The ordinary tool post is placed in this extra rest.
Fig. 514Fig. 514.
Fig. 514.
When it is desired to bolt work on the lathe carriage and rotate the cutting tools, as in the case of using boring bars, the cross slide is sunk into instead of standing above the top surface of the carriage so as to leave a flat surface to bolt the work to, andT-shaped slots are provided in the carriage, to receive bolts for fastening the work to the carriage, an example of this kind being shown inFig. 514.
Fig. 515Fig. 515.
Fig. 515.
Fig. 515represents a self-acting slide or engine lathe by William Sellers and Co., of Philadelphia. These lathes are made in various sizes from 12 inches up to 48 inches swing on the same general design, possessing the following features:—The beds or shears are made with flat tops, the carriage being gibbed to the edges of the shears, these edges being at a right angle to the top face of the bed. The dead centre spindle is locked at each end of its bearing in the tailstock, thus securing it firmly in line with the live spindle. The ordinary tool feed is operated by a feed rod in front of the lathe, and this rod is operated by a disc feed, which may be altered without stopping the lathe so as to vary the rate of tool feed; and an index is provided whereby the operator may at once set the discs to give the required rate of feed. The lead screw for screw cutting is placed in a trough running inside the lathe bed, so that it is nearer to the cutting tool than if placed outside that bed, while it is entirely protected from the lathe cuttings and from dirt or dust; and the feed-driving mechanism is so arranged that both may be in gear with the live spindle, and either the rod feed or screw-cutting feed may be put into action instantly, while putting one into action throws the other out, and thus avoid the breakage that occurs when both may be put into action at the same time. The direction of the turning feed is determined by the motion of a lever conveniently placed on the lathe carriage, and the feed may be stopped or started in either direction instantly. The mechanism for putting the cross feed in action is so constructed (in those lathes having a self-acting cross feed) that the cross feed cannot be in action at the same time as the turning feed or carriage traverse by rod feed.
Lathes of 12 and 16 inches swing are back-geared, affording six changes of speed, and the lathe tool has a vertical adjustment on a single slide rest. Lathes of 20 inches swing are back-geared with eight changes of speed. Lathes of 25 inches and up to 48 inches swing inclusive are triple-geared, affording fifteen changes of speed, having a uniformly progressive variation at each change.
Fig. 516Fig. 516.
Fig. 516.
Fig. 517Fig. 517.
Fig. 517.
The construction of the live head or headstock for a 36-inchlathe is shown in the sectional side view inFig. 516, and in the top view inFig. 517, and it will be seen that there are five changes of speed on the cone, five with the ordinary back-gear, and five additional ones obtained by means of an extra pinion on the end of the back-gear spindle, and gearing with the teeth on the circumference of the face plate, the ordinary pinion of the back-gear moving on the back-gear spindle so as to be out of the way and clear the large gear on the cone spindle when the wheel of the extra back-gear pinion is in use, as shown inFig. 517.
The front bearing of the live spindle is made of large diameter to give rigidity, and the usual collar for the face plate to screw against is thus dispensed with. End motion to the live spindle is prevented by a collar of hardened steel, this collar being fast on the live spindle and abutting on one side against the end face of the back bearing and on the other against a hardened steel thrust collar.
All these parts are enclosed in a tight cast-iron tail-block, which serves as an oil well to insure constant and perfect lubrication. The surfaces which confine the revolving collar back and front are so adjusted as to allow perfect freedom of rotary motion to the spindle and collar, but no perceptible end motion. The securing of the live spindle endwise is thus confined to the thickness of the steel collar only, and this is so enclosed in a large mass of cast iron as to insure uniformity of temperature in all its parts, hence there is no liability for the live spindle to stick or jam in its bearings, while the expansion of the live spindle endways from this collar (if it expands more than the lathe head) is allowed for in freedom of end motion through the front journal, which is a little longer than the bearing it runs in. In turning work held between the lathe centres the end thrust is taken against the hardened steel collar on the live spindle, and the hardened steel collar at the back of it, while in turning work chucked to the face plate the spindle is held in place endways by the confinement of the steel collar on the spindle between the steel collar behind it and the back end of the back bearing. With this arrangement of the spindle the change from turning between the lathe centres and turning chucked work requires no thought or attention to be given to any adjustment of the live spindle to accommodate it for the changed condition of end pressure between turning between the centres and turning chucked work, as is the case in ordinary lathes.
The double-geared lathes, as those of 12, 16 and 20 inches swing, are provided with face plates that unscrew from the live spindle to afford convenience for changing from one size of face plate to another, and all such lathes have their front live spindle journal made of sufficiently enlarged diameter above that of the screw, to afford a shoulder for the face plate to abut against. The nose of the live spindle is not threaded along its entire length, but a portion next to the shoulder is made truly cylindrical but without any thread upon it, and to this unthreaded part the face plate accurately fits so that it is held true thereby, and the screw may fit somewhat loosely so that all the friction acts to hold theface plate true and hard up against the trued face of the spindle journal. Face plates fitted in this way may be taken off and replaced as often as need be, with the assurance that they will be true when in place unless the surfaces have been abused in their fitting parts.
Fig. 518Fig. 518.
Fig. 518.
Fig. 519Fig. 519.
Fig. 519.
Fig. 520Fig. 520.
Fig. 520.
The construction of the tailstock or poppet-head, as it is sometimes termed, is shown inFigs. 518,519, and520. To hold it in line with the live spindle it is fitted between the inner edges of the bed, and it will be seen that one of the bed flanges (that on the left of the figure) is provided on its under side with aV, and the clamp is provided with a correspondingV, so that in tightening up the bolt that secures the tailstock to the bed the tailstock is drawn up to the edge of the shears, and therefore truly in line with the live spindle, while when this bolt is released the tailstock is quite free to be moved to its required position in the length of the bed. As a result of this form of design there is no wear between the clamp and the underneathV, and the tailstock need not fit tightly between the edges of the bed, hence wear between these surfaces is also avoided, while the tailstock is firmly clamped against one edge of the bed as soon as the clamp is tightened up by the bolt on that side.
Fig. 520shows the method of locking the tailstock spindle and of preventing its lateral motion in the bearing in the tailstock. At the front or dead centre end of this bearing there is between the spindle a sleeve enveloping the spindle, and coned at its outer end, fitting into a corresponding cone in the bore of the tailstock. Its bore is a fit to the dead spindle, and it is split through on the lower side. Its inner end is threaded to a sleeve that is within the headstock, and whose end is coned to fit a corresponding cone at the inner end of the bore of the tailstock.
To this second sleeve the line shown standing vertically on the left of the hand wheel is attached, so that operating this handle revolves the second sleeve and the two sleeves screw together, their coned ends abutting in their correspondingly coned seats in the tailstock bore, and thus causing the first-mentioned and split sleeve to close upon the dead centre spindle and yet be locked to the tailstock.
As the bore of the tailstock is exactly in line with the live spindle, it follows that the dead spindle will be locked also in line with it.
Fig. 521Fig. 521.
Fig. 521.
Fig. 522Fig. 522.
Fig. 522.
Figs. 521and522represent sectional views of the carriage and slide rest of these lathes of a size over 16 inches swing. On the feed rod there are two bevel pinionsp, one on each side of the bevel-wheela, and by a clutch movement either of these wheels may be placed in gear with bevel-wheela.
The clutch motion is operated by a lever which, when swung over to the right, causes the bevel pinion on the right to engagewith the bevel-wheela, and the carriage feeds to the right, while with the lever swung over to the left the carriage feeds to the left.
On the inclined shaft is a worm, or, as the makers term it, a spiral pinion of several teeth which gears into a straight toothed spur gear-wheel, giving a smooth and rolling tooth contact, and therefore producing an even and uniform feed motion.
This spur gear is fast on a shaftc, which is capable of end motion and is provided on each of its side faces with an annular toothed clutch. On each side of this spur-wheel is a clutch, one of which connects with the train of gears for the turning feed, and the other with the cross-feed gearb.
When the shaft (whose end is shown atc, and to which the spur gear referred to is fast) is pulled endways outwards from the lathe bed, its front annular clutch engages with the clutch that sets the cross-feed gearbin motion, andbengages with a pinion which forms the nut of the cross-feed screw.
When shaftcis moved endways inwards its other annular clutch engages the clutch on that side of it, and the turning feed is put into operation. The method of operating shaftcendways is asfollows:—
In a horizontal bearingdis a shaft at whose end is a weighted leverl, and on the end of this shaft is a crank pin shown engaging a sleeveewhich affords journal bearing to the outer end of shaftc, so that operating the weighted leverloperatese, and therefore shaftcwith the spur gear receiving motion from the worm. A simple catch confines leverlto either of its required limits of motion, and allows the free motion of the operating lever to start or stop either the longitudinal or the cross feed, either of which is started or stopped by this lever, but no mistake can occur as to which feed is operated, because the catch above mentioned requires to be shifted to permit the feed to be operated.
The lower end of the bell crankfengages with the sleevee, so that when the shaftcis operated outwards the horizontal arm of bell crankfis depressed and the spur pinion of the cross-feed nut is free to revolve, being driven by the cross-feed motion. When the leverfis moved towards the lathe bed (which occurs when the stop or catch is set to allow the longitudinal feed to be used) the nut of the cross feed is locked fast by the horizontal arm of the bell crankf. This device makes the whole action from one direction of feed to another automatic, and the attention of the workman is not needed for any complicated adjustment of parts preparatory to a change from one feed to the other.
Athis a hand wheel for hand feeding, the pinionrmeshing into the rack that extends along the front of the lathe bed; back of the hand wheel and ath′a clamp is provided whereby the saddle or carriage may be locked to the lathe bed when the cross feed is being used, thus obviating the use of a separate clamp on the bed.
The top slide of the compound rest is long and its guideway is short, the nut being in the stationary pieceg, and it will be observed that by this arrangement at no time does the bearing surfaces of the slides become exposed to the action of chips or dirt.
Fig. 523Fig. 523.
Fig. 523.
Fig. 523is a sectional view of the carriage and slide rest as arranged for 12 and 16-inch lathes when not provided with a self-acting cross feed. In this case end motion to shaftcis given by leverh, which is held in its adjusted position by the tonguet. In this lathe the screw-cutting and the turning feed cannot be put into gear at the same time.
The tool nut is arranged to enable the tool to be adjusted for height after it is fastened in the tool post by pivoting it to the cross slide, a springsforcing it upwards at its outer end, thus holding the tool point down and in the direction in which the pressure of the cut forces it, thus preventing the wear of the pivot from letting the tool move when it first meets the cut. The nutnis operated to adjust the tool height, and at the same time enables the depth of cut to be adjusted very minutely. A trough catches the water, cuttings, &c., and thus protects the slides and slideways from undue wear.
In all these lathes the feeding mechanism is so arranged that there are no overhanging or suspended shaft pins or spindles, each of such parts having a bearing at each end and not depending on the face surface of a collar or pin, as is common in manylathes. Furthermore, in these lathes the handle for the hand carriage feed moves to the right when the carriage moves to the right; the cross-feed screw (and the upper screw also in compound slide rests) has a left-hand thread, so that the nut being fixed the slides move in the same direction as though the nut moved as in ordinary lathes. The tailstock or poppet-head screw is a right hand because the nut moves in this case. The object of employing right-hand screws in some cases, and left-hand ones in others, is that it comes most natural in operating a screw to move it from right to left to unscrew, and from left to right to screw up a piece, this being the action of a right-hand screw, left-hand screws being comparatively rarely used in mechanism, save when to attain the object above referred to.
Fig. 524Fig. 524.
Fig. 524.
Fig. 524represents the Niles Tool Works car axle lathe, forming an example in which the work is driven from the middle of its length, leaving both ends free to be operated upon simultaneously by separate slide rests.
The work being driven from its centre enables it to rotate upon two dead centres, possessing the advantage that both being locked fast there is no liberty for the work to move, as is the case when an ordinary lathe having one live or running spindle is used, because in that case the live spindle must be held less firmly and rigidly than a dead centre, so as to avoid undue wear in the live spindle bearings; furthermore, the liability of the workman to neglect to properly adjust the bearings to take up the wear is avoided in the case of two dead centres, and no error can occur because of either of the centres running out of true, as may be the case with a rotating centre.
The cone pulley and back gear are here placed at the head of the lathe driving a shaft which runs between the lathe shears and drives a pinion which gears with the gear on the work driving head shown to stand on the middle of the shears. This head is hollow so that the axle passes through it. On the face of this gear is a Clement’s equalizing driver constructed upon the principle of that shown hereafter inFig. 756.
Fig. 525Fig. 525.
Fig. 525.
The means for giving motion to the feed screw and for enabling a quick change from the coarse roughing feed to a finer finishing feed to the cutting tool without requiring to change the gears or alter their positions, is shown inFig. 525.aandbare two separate pinions bored a working fit to the end of the driving shafts, but pierced in the bore with a recess and having four notches or featherwaysh. The end of the driving shaftsis pierced or bored to receive the handled pini, and contains four slots to receive the four feathersjwhich are fast ini. In the position shown in the figure these feathers engage with neitheranorb, hence the driving shaft would remain motionless, but it is obvious that if pinibe pushed in the feathers would engageband therefore drive it; or ifiwere pulled outwards the feathers would engageaand drive it, becauseaandbare separate pinions with a space or annular recess between them sufficient in dimensions to receive the feathers. The difference in the rate of feed is obviously obtained through the difference in diameters of the pair of wheelsa,cand the paird,b, the lathe giving to the lead screw the slowest motion and, therefore, the finest feed.
Largeimage(242 kB).Fig. 526Fig. 526.
Largeimage(242 kB).
Fig. 526.
The means for throwing the carriage in and out of feed gear with the feed screw and of providing a hand feed for operating the tool in corners or for quickly traversing the carriage, is shown inFig. 526, in whichsrepresents the feed screw andba bracketor casting bolted to the carriage and carrying the hand wheel and feed mechanism shown in the general cut figure.
bprovides a slide way denoted by the dotted lines atb, for the two halvesnandn′of the feed nut. It also carries a pivot pin shown atpin the front elevation, which screws intobas denoted byp′in the end view; upon this pivot operates the pieced, having the handled. Indare two cam groovesa a; two pinsn, which are fast in the two half-nutsn n′, pass through slotsc cinb, and into the cam groovesa arespectively.
As shown in the cut the handledofdis at its lowest point, and the half-nutsn′andnare in gear upon the feed screw; but supposedbe raised, then the groovesa awould force their respective pinsnup the slotsc, and these pinsnbeing each fast to a half of the nut, the two half-nuts would be opened clear of the feed screw, and the carriage would cease to be fed.
The hand-feed or guide-carriage traverse motion is accomplished as follows:—bprovides atejournal bearing to a stud on which is the hand wheel shown in the general cut; attached to this hand wheel is a pinion operating a large gear (also seen in general cut) whose pitch line is seen atg, in figure. The stud carryingghas journal bearing atf, and carries a pinion whose pitch circle is athand which gears with the rack.
Fig. 527, which is taken fromThe American Machinist, represents an English self-acting lathe capable of swinging work of 12 inches diameter over the top of the lathe shears, which are provided with a removable piece beneath the live centre, which when removed leaves a gap, increasing the capacity of the lathe swing. The gears for reversing the direction of feed screw motion are here placed at the end of the live head or headstock, the screw being used for feeding as well as for screw cutting.
Fig. 528represents a pattern-maker’s lathe, by the Putnam Tool Co., of Fitchburg, Massachusetts. This lathe is provided with convenient means of feeding the tool to its cut by mechanism instead of by hand, as is usually done by pattern-makers, and this improvement saves considerable time, because the necessity of frequently testing the straightness of the work is avoided.
It is provided with an iron extension shears, the upper shears sliding inV-ways provided in the lower one. The hand-wheel is connected with a shaft and pinion, which works in a rack, and is used for the purpose of changing the position of the upper bed, which is secured in its adjusted position by means of the tie bolts and nuts, as shown on the front of the lower shears. This enables the gap in the lower shears to be left open to receive work of large diameter, and has the advantage that the gap need be opened no more than is necessary to receive the required length of work. The slide-rest is operated by a worm set at an angle, so as to operate with a rolling rather than a sliding motion of the teeth, and the handle for operating the worm-shaft is balanced. The carriage is gibbed to the bed. The largest and smallest steps of the cone pulley are of iron, the intermediate steps being of wood, and a brake is provided to enable the lathe to be stopped quickly. This is an excellent improvement, because much time is often lost in stopping the lathe while running at a high velocity, or when work of large diameter is being turned. The lathe will swing work of 50 inches within the gap, and the upper shears will move sufficiently to take in 4 additional feet between the centres.
Fig. 530Fig. 530.
Fig. 530.
In the general view of the lathe,Fig. 528, the slide-rest is shown provided with aT-rest for hand tools, but as this sets in a clip or split bore, it may readily be removed and replaced by a screw tool, poppet for holding a gauge, or other necessary tool. To enable the facing of work when the gap is used, the extra attachment shown inFigs. 529and530is employed. It consists of an arm or bara, bolted to the upper shearssby a boltb, and clampc, in the usual manner, and is provided with the usual slideway and feed-screwffor operating the lower slidet, which carries a hollow stemd; overdfits a hubk, upon the upper slidee, which hub is split and has a bolt atf, by means of which the upper slide may be clamped to its adjusted angle or position. The upper sliderhreceives the tool-post, which is parallel and fits in a split hub, so that when relieved it may be rapidly raised or lowered to adjust the height of the tool.
Fig. 531Fig. 531.
Fig. 531.
Fig. 532Fig. 532.
Fig. 532.
The construction of the brake for the cone pulley is shown inFigs. 531and532, in whichprepresents the pulley rim,lthe brake lever,sa wooden shoe, andwa counter-weight. The lever is pivoted atgto a lugr, provided on the live headstock, and the brake obviously operates on the lowest part of the cone flange; hence the lever handle is depressed to put the brake in action.
The construction of the front and back bearings for the live spindle is the same as that shown inFigs. 495and496.
Fig. 533Fig. 533.
Fig. 533.
Wood turners sometimes have their lathes so made that the headstock can be turned end for end on the lathe shears, so that the face plate may project beyond the bed, enabling it to turn work of large diameter. A better method than this is to provide the projecting end of the lathe with a screw to receive the face plate as shown inFig. 533, which represents a lathe constructed by Walker Brothers of Philadelphia. At the end of the lathe is shown a hand rest upon a frame that can be moved about the floor to accommodate the location, requiring to be turned upon the work.
Fig. 534Fig. 534.
Fig. 534.
Fig. 535Fig. 535.
Fig. 535.
For very large work, wood-workers sometimes improvise a facing lathe, as shown inFig. 534, in whichais a headstock bolted to the uprightb;cis the cone pulley, andea face plate built up of wood, and fastened to an iron face plate by bolts. The legsa, of the tripod hand rest,Fig. 535, are weighted by means of the weightsb.
InFig. 536is shown a chucking lathe, especially adapted for boring and facing discs, wheels, &c. The live spindle is driven by a worm-wheel, provided around the circumference of the face plate. The driving worm (which runs in a cup of oil) is on a driving shaft, running across the lathe and standing parallel with the face of the face plate. This shaft is driven by a pulley as shown, changes of speed being effected by having a cone pulley on the counter-shaft and one on the line of shafting.
This lathe is provided with two compound slide rests. One of which may be used for boring, while the other is employed for facing purposes. These rests are adjustable for location across the bed of the lathe by means of bolts in slots, running entirely across the lathe bed.
These slide rests are given a self-acting motion by the following arrangement of parts: at the back of the live spindle is an eccentric rod, operating a connecting rod, which is attached at its lower end to the arm of a shaft running beneath the bed, and parallel to the lathe spindle. This shaft passes beyond the bed where it carries a bevel gear-wheel, which meshes with a bevel gear-wheel upon a cross shaft. This cross shaft carries three arms, one at each end and inside its journal bearings in the bed, and one beneath and at a right angle to the other two. These receive oscillating motion by reason of the eccentric connecting rod, &c.
For each compound rest there are provided two handles as usual, and in addition anLlever, one arm of the latter being provided with a series of holes, while the other carries a weight.
TheLlever carries a pawl which operates a ratchet wheel, placed on the handle end of the slide rest cross feed screw. If then a chain be attached to one of the holes of theLlever, and to the oscillating arm, the motion in one direction of the latter will be imparted to theLlever (when the chain is pulled). On the return motion of the oscillating arm, the chain hangs loose, and the weight on theLlever causes that lever arm to fall, taking up the slack of the chain, the feed taking place (when the pawl is made to engage with the ratchet wheel) during the motion of the oscillating arm from right to left, or while pulling the chain.
The rate of feed is varied by attaching the chain to different holes in theLlever.
To operate the rests in a line parallel to the lathe spindle, a similarLlever is attached by chain to the third oscillating arm, which is placed on the cross shaft, mid-way of the bed, or between the two slide rests. It is obvious then that with anLlever attachment on each feed screw, both slides of each rest may be simultaneously operated, while either one may be stopped either by detaching the chain or removing theLlever.
For operating the rests by hand, the usual feed-screw handles are used.
Fig. 537represents a 90-inch swing lathe by the Ames Manufacturing Company of Chicopee, Massachusetts.
The distinguishing feature of this lathe is that the tailstock spindle is made square, to better enable it to bear the strain due to carrying cutting tools in place of the dead centre; and by means of a pulley instead of a simple hand wheel for operating the tail spindle, that spindle may be operated from an overhead countershaft, and a tool may be put in to cut key-ways in pulleys, wheels, &c., chucked on the face plate (which of course remains stationary during the operation), thus dispensing with the necessity of cutting out such key-ways by hammer, chisel, and file, in wheel bores too large and heavy to be operated upon in a slotting machine.
On account of the weight of the tailstock it is fitted with rollers, which may be operated to lift it from the bed when it is to be moved along the lathe bed.