US2032538A - Grinding machine - Google Patents

Description

March 3, 1936. H, w. KULP ET A1. 2,032,538

DING' MACHINE Filed June 2Q, 1933 2 Sheets-Sheet l g. Fl d Q .llnmmum ral' Q Q March 3, 1936. H. w. KULP ET Al.

GRINDING MACHINE Filed June 20, 1953 v2 sheets-sheet 2 Patented Mar. '3, 1936 PATENT OFFICE GRINDING MACHINE Harry W. Kulp and Martin C. Dellinger, Lancaster, Pa., assignors to K-D Manufacturing Company, Lancaster, Pennsylvania Pa., a corporation of Application June 20, 1933, Serial No. 676,732

11 Claims. (Cl. 51--l24) This invention relates to a grinding machine and is intended primarily for grinding valve stems of internal combustion engines to exact predetermined lengths without removal from the machine.

Under present day practices in connection with the usual valve grinding operation it .is usual to ream or reseat the valve seatsof internal combustion engines, involving the actual removal of U a substantial amount of metal as distinguished from the old practice of grinding the valve seats with an abrasive compound to simply remove the carbon that may have collected on the valve seat. Such reaming or reseating results in varying the distance between the'upper face of the valve tappet when in its lowest position and the face of the valve seat as thus reamed or reseated, such distance being decreased by from one sigtyfourth to one thirty-second of an inch each time the valve seat is thus reamed or reseated incident to the successive valve grinding operations during the normal life of the car.

This variation in distances is compensated for in most makes of cars by adjusting the valve tappets accordingly, but in at least one popular make of car in practically universal use at the present time there is no provision for adjusting the tappets and the only way to compensate for the decrease in distance between the face of .the valve seat and the face of the valve tappet is to grind off the end of the valve stem, allowance being made as usual for variation in the length o-f the valve stem due to expansion as the engine warms up and due to contraction as the engine cools olf when out of use.

The setting or gap allowed to take care of expansion and contraction may vary within reasonable limits, but for the Ford Model A, the make of car specically in mind, the gap or clearance should preferably be about twelve one thousandths of an inch between the top of the valve tappet and the bottom of the lower end of the valve stem.

Heretofore it has been usual practice for the mechanic to grind off the end of a valve stem simply by holding the valve stem in his hand and sho-ving it against the face ofthe grinder until he thought he had ground it off about enough and to then put the valve in the engine block, which involved inserting the usual valvev stem guide bushings, to try it out. Usually three or four attempts per valve were necessary, involving a con# 'siderable waste of the mechanics time in replacing andremoving each one of the valves a number of diierent times, and the result was simply guess work in which almost certainly no one of the valve stems would be of exactly the correct length. Also such guess work resulted in an unnecessary waste of material inasmuch as every once in awhile a mechanic would grind off a valve stem to such an extent that it would be so short it could not be used and would have to be discarded.

The present invention has been evolved with the above considerations particularly in view and has for its primary objects to provide a work holder whereby the lower end of the bottom of the valve stem may be set in proper initial position as required by the newly decreased distance between -the valve seat and the top of the valve tappet and may thereafter be progressively' alternately moved toward the grinder and ground so as to remove each time a thousandth or two one-thousandths of an inch of material from the end of thev valve stem until the desired gap or allowance of twelve one-thousandths of an inch, or more or less if preferredby the mechanic or required by any particular car, is provided for, all without removing the work from the work holder once the grinding o-peration has been 25 started until it has been completed; to provide in connection with such a work holder means whereby the same amount of metal may be removed from the end of each valve stem of a given engine-to provide for exact uniformity inthe gap or allowance to compensate for expansion and contraction, even though each valve stem may be of slightly different length by va few thousandths of an inch from each of the other valvestems; to provide a special setting gage for determining the distance between the upper face of a particular valve seat and the upper face of its cooperating Valve tappet; to provide a work holder which may be adjusted in position to accommodate valve stems varying greatly in length as for different models of cars Without disturbing y the precision feedgto provide a work holder chuck freely independentlysinitially adjustable toward the grinding means andaxially of its precision adjustable support on which it is mounted, in combination with means for locking said chuck in any position of adjustment with relation to said support to move endwise therewith in accordance with the subsequent precision adjustment of the latter; to provide a simple spring expanded chuck means for the Work;` to provide said means being placed in the work-holder in place of the gage and of the valve stem and being precision adjusted toward the face of the grinding wheel; to provide in association with saidgrinding gage automatic means for rendering the grinder inoperative as the grinding gage is moved into operative position and for throwingvthe grinder into operation when the grinding gage is` moved back out of operative position; and to improve various details of operation and construction as hereinafter more specically set forth. and described.

In this application we show and describe only the present preferred embodiment of our invention simply by way of illustration of the practice thereof, as by law required. However, we are aware that our invention is capable of other and diiierent embodiments, and that the several details thereof may be modified in various ways, all without departing from our said invention, and therefore the drawings and description herein are to be consideredas merely illustrative and not as exclusive.

In the accompanying drawings:

Figure 1 represents a top plan view of a machine embodying our invention;

Figure 2, a side elevation thereof;

Figure 3, a central'longitudinal section through the work holder, the supporting base A on which it is mounted, and the grinder D;

Figure 4, a detail cross sectional view on line 4 4 of Fig. 2;

Figure 5, a fragmentary detail cross sectional view. on the line 5-5 of Fig. 2;

Figure 6, a fragmentary detail longitudinal sectionalfview through the operative end of a dressing,tool disposed in the chuck member 3 of the work holder;

Figure 7, a fragmentary detail inner end elevation of chuck member I;

Figure 8, a similar view of chuck member 2;

Figure 9, a front elevation, on line 9-9 of Fig. l, of the grinder D and the grinding gage 33 swung over into operative position with relation to grinding wheel D;

Figure 10, a top plan view of the parts shown in Fig. 9, the shaft 3| being broken away; and

Figure 11, a sectional view on line II-II of Fig. 1, the base I, switch box F and switch lever G being shown in elevation, and with the arm 33 shown in its other extreme position wherein it has moved the switch lever G to energize the motor B.

Referring now in detail to the drawings, A designates the machine base on which is mounted the electric motor B having a driven rotating shaft C on which is mounted a grinding disc or velement D preferably of the radial face grinding type, said motor B being controlled ,by a usual switch box F having a snap-.switch control lever G of conventional well known construction movable to its extreme position to the left to close the circuit to energize the motor B and movable to the right to its extreme position to de-energize the motor B. The motor B is secured to the base A by means of bolts H so as to beimmovable with relation to said base A and whereby its shaft C and grinding wheel or element D will be held in definite xed relation to the base 2A and other parts mounted thereon. v

A work holder is rigidly mounted on the A in operative position in front of thegrindril by means of suitable bolts 6 passing through'the respective end block members 4 and 5 of said work holder and comprises a support element I mounted for endwise movement between said end blocks 4 and 5; a main chuck member 2 mounted for movement endwise of the support I for adjustment endwise thereof, means being provided for locking the main chuck member 2 in any desired position of adjustment endwise of the support I; and a supplementary chuck member 3.

The support member I may be cylindrical in form throughout its length as illustrated but if not preferably its ends will be cylindrical to bel received in land to turn in the respective opposed end portions of the end blocks or brackets 4 and 5, whereby the work holder chuck comprising the main member 2 and the supplementary member 3 may have a swinging movement about the axis of the support 2 to move the end of the work to be operated upon or ground in`a sweeping path across the radial grinding face of the grinder D in accordance with usual practice.

Both of the blocks 4 and 5 have horizontal arm portions which are centrally longitudinally bored to receive the corresponding end portions of the body I, the bore in the block 4 being continued to form a socket 1 in which a helical compression spring 8 is located, being interposed between the outer end of said bore and the opposed outer end of the support I, said socket 1 being of a diameter at least equal to the diameter of the adjacent portion of the support I so as to receive the same, and said spring 8 being normally under a substantial pressure and tending to force the support I toward the end block 5.

An adjusting screw 9 having its axis coincident y with the axis of the support I is threaded through the end block or bracket 5 and `bears with its inner rounded end against the opposed end face 0f the support I, so that as said screw 9 is turned into the bracket 5 its end will engage the encl of support I and force the same endwise against the opposing action of the pressure spring 8, and so that as said screw 9 is turned in reverse direction to move it away from support I, the latter will be pressed against the end of the screw 9 by the compression spring 9. An index finger I0 is rigidly secured to the squared head of the screw 9 to move over the graduated face of the scale I I held rigid with relation to the end block 5. Said screwV 9 is formed with twenty threads to the inch in length, so that one complete revolution of the screw about its axis would result in moving it endwise bodily inthe end block 5 ifty one thousandths of an inch and so that consequently a movement of degrees would move it endwise a total of twenty-nve-one thousandths of an inch and the scale II will be graduated for each one-thousandth of an inch and will extend for`180 degrees about the axis of the screw 9.

The main chuck member 2 is formed with a lower longitudinal opening corresponding in form to, and to receive in an endwise direction, the support I, whereby the chuck may be mounted on the support I, and is provided above said opening with two longitudinally extending bores I3 and I5 respectively parallel with each other and with said lower opening, and Athe supplementary chuck member 3 is provided with two supporting and guiding rods or stems I2 and I4 respectively telescopically received in said bores i3v and llzthe ,supporting rod .or stem I4 being ormedwitlrabore. I5 extending for most of its 'length' -an'dybeingin communication with the bore I5;` a. helical spring I1 normally under compression being disposed inthe axially aligned end walls thereof respectively to force'the supplementary chuck element 3 away from the main chuck element 2. The upper edge portion of main chuck' element 2 is provided with a slot 2 to receive the sleeye 25 of the work gage and the stem E ofthe valve, and the outer end face of the main socket member 2 adjacent said slot 2is lformed with a conicalseat I8 to receive and. center the corresponding conical Vface 28 of the work gage and the corresponding conical face E of the valve being operated upon. The

supplementary chuck member 3 has its upper A portion similarly formedwith a slot 3sl to receive the stem 23 of the work gage or the stem E of the valve or the stem of the dressing tool I as the case may be, and has its inner face adjacent said slot 3l formed with a conical face I9 to receive and center the corresponding con, ical face 24 of the work gage, or the correspondingly shaped conical face E2 of the enlarged or mushroomed lower end of the valve stem -E, or the similarly shaped face I of the similarly formed end of dressing tool I.

A clamping screw passing through the main chuck member 2 has a head 2| having a clamping beveled face 2|n adapted to be drawn by the wing nut 22 into tight frictional engagement with the support I to lock said chuck member 2 in any desired position of adjustment axially of said support I.

The work gage sleeve 25 is centrally longitudinally bored to adjustably receive the stem 23 and beyond the conical face 26 Ais formed with a transverse perforation to receive a bolt 28 having a clamping head 29 adapted to be drawn into tight clamping engagement with the stem 23, or the stem of the dressing tool I, by means of a wing nut 38 turning on the thread of said screw 28, whereby said sleeve 25 may be clamped on the stem 23 in such position as may be necessary to accord with ther exact distance between the upper face of the tappet, corresponding to the lower face of the end 24 of the stem 23,

4and the upper face of the valve seat correspondthe supplementary chuck member 3 will be released, and the conical seats I8 and I9 in bearing against the respective cooperating conical faces 26 and 24 of the gage will center the same.

The grinding gage 33 is then swung to the position shown in Figs. 1 and 2 and the chuck member 2 with its supplementary member 3 isv then adjusted axially of the support I until the ,extreme end of the enlarged end portion 24 of the work gage 23 strikes against the gage face 34, when the screw 9 is to be turned to the left to zero. Thereafter the nut 22 is turned up on the screw 20 to draw the clamping beveled face 2|a into tight engagement with support I to lock the chuck member 2 in adjusted position. The supplementary chuck member 3 is then again pressed toward main chuck member 2 to remove the work gage and replace the same by the valve having the stem E, upper .conical face E' and lower conical face E, and which is to be ground oil' as made necessary by the reaming or reseating of its seat.

The grinding gage 33 is formed with a feelerface 35 to engage the radial grinding face of the grinder D and on its opposite side is formed with a gage face 34 to be lengaged by the end of the work gage, said faces 35 and 34 lying in the same plane at right angles to the axis of the shaft 3| on which the gage 33 is rigidly mounted and parallel to the radial grinding face of the grinder D. The shaft 3l is mounted in a bearing 32 rigid with base A and is capable of endwise movement therein to compensate for the wearing away of said radial grinding face, and the gage 33 will be secured to said shaft 3|to turn therewith by any suitable means, such as a rivet or pin 38.

Preferably the main socket member 2 will -'nave cylindrically bored end-bosses to receive the corresponding horizontal portions of the respective end blocks or brackets 4 and 5, felt packing rings 31 being interposed between the opposed cylindrical faces to seal the support I against the ingress of grit and other foreign matter, and preferably these felt packing rings 31 will be seated in external annular grooves in the respective end brackets 4 and 5 respectively to guard against their displacement.

The switch throwing arm 38 threaded over the rear end of the shaft 3| and having a radially inwardly presented lug 39 slidably received in the groove 48 extending from the rear end of the shaft 3| turns the said shaft 3| in accordance with the movement of the grinding gage 33, so that as the grinding gage 33 is swung toward its operative position illustrated inFig. .1, the hook 42 pivotally mounted by pin 43 on the arm 38 and engaged over the upper end of the switch lever G will spring the latter to the right to off position to deenergize the motor B, and so that when the grinding gage 33 is swung back out of operative position the tip 4| of the arm 38 will strike against the switch lever G then in its off position and will knock or kick it over to the left into its operative position to energize the motor B. To yieldingly hold the hook 42 in position to engage over the upper end of the switch lever G, a little leaf spring 42' may be secured or riveted to the arm 38 to bear with its free end against the hook 42.

In order to maintain the arm 38 in proper alignment with the switch lever G to throw the same to on and off positions according as the grinding gage is swung back out of operative position and moved back into operative position, and to permit the shaft 3| to move endwise as may be necessary in accordance with the wearing away of the face of the grinding wheel D, a sheet metal holder 41 is secured to the under side of the bearing 32 at the rear end thereof to extend in a peripheral direction partially about the lower face thereof and has an upstanding flange 48 extending upward parallel to and in sliding engagement with the rear face of the hub of the arm 38, so holding said arm 38 against axial movement and in loose sliding engagement with the rear end of the bearing 32. Preferably a sheet metal cap 45 will be secured to the extreme rear end of the shaft 3| by any suitable means,l for instance by a rivet or pin 46 extending through said shaft 3| and engaging said cap 45 on opposite sides thereof. i

The dressing tool I may be formed with a stem corresponding in diameter and in length to the n of the gage to be slidably received in the corresponding element of the measuring The said dressing tool has an enlarged or mushroomed inner end 24 which corresponds in size and shape to the enlarged or mushroomed end 24 of the stem 23 of the measuring gage and conical face adapted to seat in and be centeredby the conical seat or face I9 of the supplementary chuck member 3, A dressing diamond. Il is practices so as to be permanently rigidly-'held therein, and projects beycnd all other portionsof the rear end face of said head 24 so that whenv the dressing tool I is mounted in the work holder and oscillated or swung back and forth. acrossA the grinding face of the grinder D it alone of the. dressing tool will be in contact with the grinder` D v Y and will trim up or dress the face of said grinder Instead I in accordance with well known practice. of being formed as above described, it is obvious that the stem of the dressing tool might be continued for a suitable length, for instance for a length corresponding to the length of the usual valve stem and might be provided at its forward end with a head having a centering conical face corresponding in size and shape to the conical face 'E' of the valve illustrated in Fig. 3, so as to center that end of the dressing tool in the conical seat or face I8 of the main chuck member 2, whereby the dressing tool could be used entirely independently of all portions of the measuring gage.

Having thus described our invention, what we claim as new and desire to secure by U. S. Letters Patent is:

1. A grinding machine comprising a radial face rotary grinder mounted in fixed position free to rotate and a work holder and precision feeder comprising a pair of axially aligned lspaced supports fonugid with opposed co-axial cylindrical sockets, said supports being rigidly located in advance of, and on a line parallel to the axis of, said grinder, in combination with a supporting shaft having its end portions snugly slidably received in said sockets for partial rotary movement therein, a. spring interposed in the socket of the rear support between the end Wall of said socket and the opposed rear end of said shaft and tending to force said shaft toward the front support, an adjusting screw concentric with said shaft engaging in and extending through the front support and bearing against the center of the forward end of said shaft, said screw being adjustable to force said shaft axially toward said spring against the action of the latter and to permit said shaft to be moved axially in the reverse direction under the influence of said spring, an indexfinger secured to said screw to turn therewith, a graduated scale mounted adjacent to said indexfinger to be traversed thereby, a chuck mounted on said shaft and adapted to have free sliding and free swinging movement thereon independently thereof, and quickly releasable means for locking said chuck to said shaft in any desired position axially thereof whereby said chuck as so locked to said shaft will move therewithv in a direction axially of the latter as said shaft is adjusted in an axial direction in accordance with the adjustment of said screw and whereby said supporting.

-socket ofxth g partially embedded in the enlarged or -mush-f Yshaft andjtendingvtoff roomed end 24 in accordance with well knowny :,osasss man and chucxmy swing toitnsrm opposite' directions about the axis of said shaft.

2. A grinding machinecomprising a radial face rotary grinderfmounted in fixed position free to 4 rotate anda .work vholderv andfprecision feeder comprising a, pair oi' axially spaced 'sup-l ports forrnecifwitl'i opposed co-axial sockets, said supports beingrigidiylocated von a line parallel to the ,axislofsaidgrinden in combination with a ving'its `endfportions snugly slldeblmfefv'din movement-therein #Plng'lnterposed in the be'tlireenthe end wall Ppsed rear end of said fvsaid.- .Shaft toward the vfront support, 'an adjusting screw engaging in and extending through the front support and lbearing against the forward end of said shaft, 4an index-nger secured to-said screw to turn therewith, a graduated scale mounted adjacent to said index-finger to be traversedthereby, a chuck mounted on said shaft and adapted to.have free sliding movement thereon independently thereof, and quickly releasable means for locking said chuck to said shaft in any desired position axially thereof.

siiiitorpartial'rotary v 3. A grinding machine comprising a radiall face rotary grinder mounted in fixed position free to rotate and a work holder and precision feeder comprising a pair of axially aligned spaced supports formed with opposed co-axial sockets, said supports being rigidly located with relation to said grinder, in combination with a supporting shaft havingits end portions snugly slidably received in said sockets for partial rotary movement therein, a spring interposed in one of said sockets between the end wall thereof and the opposed end of said shaft, an adjusting means engaging in and extending through the other support and bearing against the other end of said shaft, an index-finger secured to said screw to turn therewith, a graduated scale mounted adjacent to said index-finger to be traversed thereby, a chuck mounted on said shaft 'and adapted to have free sliding movement thereon independently thereof, and quickly releasable means for locking said chuck to said shaft in any desired position axially thereof. l

4.- A grinding machine comprising a radial face rotary grinder mounted in fixed position free to rotate and a work holder and precision feeder comprising a pair'of axially aligned spaced supports formed with opposed co-axial sockets, said supports being rigidly located in advance on a line parallel to the axis of said grinder, in cornbination with a supporting shaft having its end portions snugly slidably received in said sockets for partial rotary movement therein, a spring interposed in one of said sockets between the end wall thereof and the opposed end of said shaft, an adjusting means engaging in and extending through the other support and bearing against the other end of said shaft, a chuck mounted on said shaft'and adapted to have free sliding movement thereon, independently thereof, and a single quickly releasable means for locking said chuck to said shaft in any desired position axially thereof. ,f

5. An attachment for a grinding machine, said attachment comprising a pair of supports adapted to be rigidly located in axially aligned spaced relation and being formed with opposed co-axial cylindrical sockets, in combination with a supporting shaft having its end portions snugly slid-A movement therein, a spring interposed in one of said sockets between the end wall thereof and the opposed end of said shaft, an adjusting means engaging in and extending through the other support and bearing against the other end of said shaft, a chuck mounted on said shaft and adapted to have free sliding movement thereon independently thereof, and a single quickly releasable means for locking said chuck to said shaft in any desired position axially thereof.

6. A grinding machine comprising a radial face rotary grinder, means for mounting said grinder in a fixed position free to rotate, an electric motor for -rotating said grinder, a work holder and a grinding gage movable into operative position to engage the radial face of said grinder with a rearwardly presented face portion of said grinding gage and to be engaged in the same vertical plane on a forwardly presented face by the work held in said holder and adapted to be moved to inoperative position so as to be out of the way during the grinding operation, in combination with a shaft, means for rigidly securing said grinding gage to said shaft to move therewith, means for mounting said shaft to permit partial rotation thereof and for permitting movement of said shaft in an axial direction, a switch lever for controlling said motor, an 'actuating lever engaging said shaft to turn therewith and through which said shaft may slide, means for holding said actuating lever against movement in the direction of the axis of said shaft, and a supplementary actuating hook mounted on said actuating lever, said actuating lever being mounted on said shaft in such relation to said gauge and to said switch lever that when said gage is moved into inoperative position the said actuating lever will strike against the electric switch lever and move it to on or energized position and at the same time the supplementary hook carried by said actuating lever will engage and ride up over and hook over the top of said electric switch lever so that as said actuating lever is moved in the reverse direction incident to a subsequent movement of the gage to operative position, said supplementary hook will pull the electric switch lever over to its off position to de-energize the motor.

7. A grinding machine comprising a radial face rotary grinder, means for mounting said grinder in a fixed position free to rotate, means for rotating said grinder, a work holder and a grinding gage movable into operative position to engage the radial face of said grinder with a rearwardly presented face portion of said grinding gage and to be engaged in the same vertical plane on a forwardly presented face bythe work held in said holder and adapted to be moved to inoperative position so as to be out of the way during the grinding operation, in combination with a shaft, means for rigidly securing said grinding .gage to said shaft to move therewith, means for mounting vsaid shaft to permit partial rotation thereof and for permitting movement of said shaft in an axial direction, a lever for controlling said rotating means, an actuating lever engaging said shaft to turn therewith and through which said shaft may slide, means for holding said actuating lever against movement in thedirection of the axis of said shaft, and supplementary actuating means mounted on said actuating lever, said actuating lever being mounted on said shaft in such relation to said gage and to said control lever that when said shaft is partially rotated incident to the moving of said gage into inoperative position the said actuating lever in making `a partial rotation with said shaft will strike against the control lever and move the latter to position vto cause rotation of thegrinder, and at the same time the supplementary actuating means carried by said actuating lever will positively engage said control lever so that as said actuating lever is moved in the reverse direction incident to a subsequent movement of the gage to operative position, said supplementary hook will pull the control lever over to its other extreme operative position to stop rotation of the grinder.

8. A work holder for a grinding machine, said work holder comprising a pair of rigidly located axially aligned opposed supports formed with opposed co-axial externally `cylindrical arms extending toward each other, said arms being formed with co-axial sockets, a shaft extending between said supports and having cylindrical end portions telescopically received in said sockets and supported thereby for partial rotary movement therein, means for moving said shaft axially in said sockets, in combination with a main chuck member having a bore slidably receiving said shaft and formed with end flanges having cylindrical end faces concentric with said bore and telescopically receiving the respective externally cylindrical arms, annular packing means respectively received in said cylindrical arms and engaging the respective opposed cylindrical inner face of the respective flanges, said chuck member being adapted'to be freely slidable axially of said shaft independently thereof, and means for locking said chuck member to said shaft in any desired position of adjustment axially of the latter.

9. A work holder for a grinding machine, said work holder comprising a supporting shaft, means for mounting said shaft for oscillatory partial rotation, means for bodily moving said shaft to any desired position of adjustment in the direction of its axis, a main chuck member mounted on said shaft and adapted to be moved with relation thereto axially thereof, in combination with a supplementary chuck member, a plurality of parallel rods forming portions of said chuck member and snugly telescopically received in corresponding bores formed in said main chuck member and parallel to said shaft, a helical spring interposed between said chuck members and acting to force the supplementary chuck member away from said main chuck member, each of said chuck members being formed with a slotted portion and being formed on their distant end faces with concentric interrupted conical centering seats into which said slots lead, said conical centering seats being adapted to engage the corresponding conical faces on the work to center the latter under the influence of said helical spring.

l0. A work holder for a grinding machine, said work holder comprising a supporting shaft, means for mounting said shaft for partial rotation, means for bodilyl moving said shaft to any desired position of adjustment in the direction of its axis, a main chuck member mounted on said shaft and adapted to be moved with relation thereto axially thereof, and means for locking said main chuck member to said shaft in any desired position of axial adjustment thereof, in combination with a supplementary chuck member, telescopic means for mounting said supplementary chuck member on said main chuck -member, resilient means acting to force the supplementary chuck member away from said main` y chuck member, each of said chuck members being formed with a slotted portion and being .formed on their distant end faces with concentric interrupted conical centering seats into which said slots lead, said conical centering seats being adapted to engage the corresponding conical faces on the work to center the latter under the influence o`f said resilient means.

11. A device for dressing the radial fa'ce of a rotary grinder, said device comprising a shaft, means for'mounting said shaftfor oscillatory partial rotation, means for precision adjusting said shaft endwse by successive stages, a main chuck member mounted on said shaft and adjustable endwse thereof with relation thereto, means for locking said main chuck member to said shaft in any position of adjustment to move therewith, a supplementary chuck member carried by said main chuck member, resilient means tending to force said supplementary chuck member away from said main chuck member. said chuck member being formed with oppositely presented beveled .concentric centering faces, and a dressing tool carrying a grinder dressing diamond and formed with beveled centering faces respectively corresponding in shape, size and direction to the respective corresponding beveled centering faces of said chuck members and to be engaged and centered thereby in such manner 10 same by saidv precision adjustment means of said 15 shaft.

HARRY W. KULP. MARTIN c. DELLINGER.

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