US927949A

US927949A - Lens-grinding machine.

Info

Publication number: US927949A
Application number: US43644908A
Authority: US
Inventors: Bennett F Clark
Original assignee: STANDARD OPTICAL CO
Current assignee: STANDARD OPTICAL Co
Priority date: 1908-06-03
Filing date: 1908-06-03
Publication date: 1909-07-13
Anticipated expiration: 1926-07-13

Description

B. P. CLARK. LENS GRINDING MACHINE. APPLIGATION FILED JUNE 3, 1908.

4 SHEETS-SHEET 1.

ANDREW- I GM 00., Pmmmmmmml. wnmuafum n. c.

Patented Jilly 13. 1909.

B. F. CLARK. LENS GRINDING MACHINE. APPLICATION FILED JUNE 3, 1908.

Patented July 13, 1909; 4 HIEETk-BEQET 2;

nonwm 0mm! m. rmwutmum wAmYon, mp.

B.F.GLARK. LENS GRINDING MACHINE. APPLIOATION FILED JUNE 3, 1908. 927,949, Patented July 13, 1909.

4 SHEETS-BHEET 3.

munew. a. email no. Pnoro-mwhumen. wwmfoh. n. c.

B. P. CLARK. LENS GRINDING momma APPLICATION FILED JUNE 3, 1908. 9275 949, Patented July 13, 1909.-

ANDREW. I. alum! on. mro-Lmmr wlsl WASHINGTON. uv c.

q STATEsrATENT omen.

ENNETT E. e A or GENEVA, NEW YORK; ASSIGNOR TO THE STANDARD OPTICAL M- PANY, or GENEVA, NEW YORK, A CORPORATION or NEW YORK.

LENS-GRINDING MAcHINE.

To all whom it may concern: i

Be it known that I,-BENN TT F. CL RK,

nection with the accompanying drawings, is

abutment for determining the size and form of the lens.

The main object of my present inventio is to combine the grinding mechanism, lens holder and truing device together with the various adjusting devices and actuating mechanisms in a'single compact machine and with as few parts as may be consistent with the various functions which the machine as a whole is adapted to perform.

"One of the specific objects of my present inventionis to provide means for simultaneously sto ing the action of the machine when the lens "olderwith the lens therein is moved away from the grindstone and also for throwing the mechanisminto action when the lens holder is forced to its operativeposition for grinding the lenses.

Another specific object is to rovide a simple and practical means where y the degree of pressure ofthe lens clamps upon the ens may be varied at will during the opera tion of the machine.

A further object is to provide means for varying the degree of pressure of the lens against the grindstone, and a still further object is to provide a simple, and practical a'djusting means for the contact plate for the lens form or pattern and for varying the sizes of the lensesaccording to graduations with which the adjusting device is provided.

Another object is to provide simple means for automatically reciprocating the grindstone axially soasfto bring all parts ofits grinding face into contact with the lenses during the grinding operation thereby avoiding. undue wear in any one particular place. Another bject is to ermanently assoc ate with the grindingmec anism a suitable tru-" Specification of LettersPatent.

.ous features of my invention.

. Patented July 13, 1909.

Application filed June s, 1908. Serial No. 436,449.

ing device for keeping the face ofthe grindstone exactly concentric and parallel with the axis. 1 i i Other objects and'use's will be brought out in the following description. In the drawingsl igures 1 and 2 are respectively a top plan andside elevation of a lens grinding machine embodying the Vail?"

F

6, 7, 8 and 9 are sectional views taken respectively on lines 3,-3, 44, 55, 6 -6, 77, 88 and 99, Fig. 1, Figs. 5,6, 7, 8 and 9 being enlarged. j j

In carrying out the objects statedl provide a substantially rectangular su porting base or frame 1 which is provi ed with suitable feet and adapted to rest upon a bench, table or other available support and upon which is mounted the several coacting mechanisms of the complete machine as will be hereinafter described. This frame is preferably made of cast iron or other suitable metal and is provided withan integral substantially semi-circular hopper 2 centrally therein and open atthe top for receiving the lower half of a grindstone 3, the transverse interior width of the hopper or grindstone receptacle being somewhat greater than thecorresponding width of the grind stone to permit axial movement of the latter in either direction. This grindstone is provided with a' comparatively large central circular opening 4 in which is fitted a circular disk -5--, the grindstone being secured to the periphery of the disk 5 by an interposed bond 6' of melted sulfur or other adhesive or cementitious material so that the disk and securing means of the grindstone lie wholly within the plane of said grindstone thereby obviating the usual clamping disks and lock nut at opposite sides of the stone.

The disk .5 is preferably formed of metal and is centrally mounted upon a revolving shaft 7 which in this instance extends some distance beyond the faces of the grindstone and is journaled at its oppo site ends in suitable bearings 8.- These bearings -8- are adjustable forwardly and rearwardly along and upon the grindstone receptacle or hopper 2 asbcst seen in Figs. 4 and 7 and for this purpose the upper wise slots -9.for receiving the lower 1 ends of clamping bolts which are passed through apertures in the front and rear portions of the bearings 8. and engage threaded plates 11 on the under sides of said flanges whereby the bearings and shaft 7- together with the disk 5- and grindstone 3 may be held in their adjusted position, the obj eet of this adjustment being to permit the grindstone to be shifted toward the lens holder as it is worn away by abrasion;

One end of the grindstone shaft 7 is provided with a driving pulley f12 adapted to be connected to any available source of power by a belt, not shown. The opposite end of said shaft is provided with a. drlve worm -13. meshing with an underlying worm gear 14 which is loosely mounted upon a shaft 15 to permit the driving shaft 7 and parts rigidly mounted thereon together with the worm gear 14 to be continuously rotated independently of the rotation of the lens holder and its driving mechanism, presently described.

The shaft 15 is journaled in suitable bearings -16 and 17 as best seen in Figs. 2 and 5, one of which as the bearing 16 is preferably integral with the main supporting frame or bed 1 while the bearing 17 forms a part of a bracket 18 which is secured by one of the clamping screws l0- to the adjacent bearings 8 and is, therefore, movable with the grindstone when the latter is adjusted toward or from the lens holder in the manner previously referred to and is also adapted to slide along the shaft 15, the latter being held from lengthwise movement by a collar 19 and a worm 20 located at opposite ends of and in close proximity to the bearing 16 as best seen in Fig. 5. This shaft 15 is adapted to be thrown into and out of operative connection with the worm gear 14 by means of a sliding clutch element 21 which is feathered or splined upon the rear end of the shaft 15 and is movable into and out of interlocking engagement with the adjacentface of a worm gear 22, the latter forming a part of the driving mechanism for reciprocating the grindstone axially while the worm 20 at the opposite end of the shaft forms a part of the mechanism for rotating the lens holder and pattern coaxial therewith, both of which mechanisms will be presently described. The Worm 22- meshes with a worm gear 23 which is loosely mounted upon a supporting pin or stud 24 and is provided at its outer end with a hub 25 having a cam groove Z6 therein for receiving a stud or roller 27. This stud or roller is mounted upon the upper end of a laterally swinging arm or bracket 28- having its upper end slotted and engaged with the adjacent end of the grindstone shaft -"7 be tween a pair of shoulders ,29 while its lower end is fulcrumed or pivoted upon a suitable supporting pin 30 as best'seen in Fig. 4.

The worm 22, gear 23 and cam collar 25 together with the roller stud 27 and laterally swinging arm 28 constitutes mechanism for shifting the grindstone and its sup orting shaft axially or across the edge 0' the lens and when the clutch 21 is thrown out of operative connection with the worm 22 and worm gear 14- by sliding it rearwardly lengthwise of the shaft, the grindstone together with its axially shifting mechanism may be rotated continuously independently of the lens holder during which time the grindstone may be trued by a. suitable abrasive tool 31 which is adjustably clamped in a sliding support 32, the latter being adjustable radially in a suitable supporting frame 33 on the rearend of the hopper -'-2, said sliding support 32 and abrasive cutter 31 thereon being adjustable radially of the hand screw 34 as best seen in Fig. 9 although the abrasive body -3l has an independent adjustment and is held in lace by a clamp plate 35 and suitable c amping screws 36 as best seen in Fig. 9.

The supporting frame 33 is preferably secured to the upper face of the rear end of the hopper 2- by screws 38 also seen in Fig. 9 and it is, therefore, evident that this entire truing device forms a permanent part of the complete machine and is always ready for use and may be brought into action at any time either during the grinding of the lens or when the lens holder is thrown out of action. 1

The clutch element 21- is thrown into and out of. operative connection with the worm gear 14- or rather with the worm 22 thereon through the medium of a hand lever -37-, link 39- and intermediate upright lever 40, the latter lever being fulcrumed at 41 intermediate its ends and has its lower end, provided with a stud 42 which rides in an annular groove in the clutch member 21 while the upper end of said lever 40 is connected wlth a loss motion to a head 43 on the rear end of the link 39. The hand lever 37 is fulcrumed at its lower end at 4:l to the upper side of the bearing 16 and is connected intermediate its ends to the adjacent end of the link 39 while its upper end is provided with a suitable hand piece by which it may be manipulated backward and forward to rock-the lever 40 and thereby shift the clutch element 21 to connect and dis,- connect the shaft 15 to and from the loose worm gear v -14 thereon. This clutch element and its operating mechanism 139 sa a idly secured to one end of a horizontal shaft '51 and meshes with a superposed gear "52-+, the opposite end of said shaft being also provided with. a pinion 53 rigid thereon and meshing with a superposed gear 54 which is coaxial with the gear 52-. The opposite ends of the shaft --51- are journaled in suitable bearings 55 rising from the top of opposite ends of the supporting bed or frame 1, said shaft -51 reyolving in the bearings and forming a beari-ng fora rocking frame"56 as best seen in Fig. 6 and upon which the lens holder is mounted in a manner which I will now de: scribe. A i i The swinging frame 56- is provided p with opposite upright bearings 58- and spindle '.59, oneoi which as the left end bearing 58- receives and supports a revoluble 60 j which extends entirely through the bea ring 58 and receives at its outer end the gear --54 while the inner end is provided with an enlarged head against endwise movement.

Ita-te with the spindle -6 1;thehub of the gear -54- and head '61 engaging the opposite end faces of the hearing -58 to hold the spindle The head -61 is provided with a central inwardly projecting stud -62- and eccentric pin 63 which enter "corresponding apertures in a pattern or lens forming plate 64 for locking said plate to the head -61- to ro- This machine is adapted to grind, form and sizeone or aplu-rality of lenses at once and in order that these lenses may be expeditiously and correctly placed in the lens holder with their optical axes in registration with each other and with thatoi' the patternor former, I provide the spindle 60 'with an auxiliary re locked to rotate withthe spindle 60- but is removable endwise from or with the pattern -64- when necessary, as -l'or instance when properly positioning the lens relatively to the pattern or former -64-'-. This auxiliary head 65 is particularly useful in connection with a lens adjusting tool, not shown, and forming the subject matter of my pending application No. 486,448, filed June 8, 19055.net necessary to herein illustrateo'r describe, it being suflicient tosay that the auxiliary head 65 is provided with a fiangesimilar in general-outline to the eontouroffthe pattern 64 and is provided S15 yielding'engagingf ace 66oi rubber ing loosely mounted upon the adjacent end' of a rotary spindle -69 which is feathered or splined to and within a rotary sleeve 70 as best seen in Fig. 6. This sleeve 7() is journaled directly in the bearing 59 and surrounds the intermediate portion of the spindle 69, the inner end of said sleeve being provided with an annular flange 7 1-- engaging the adjacent end 01 the bearing 59-- to prevent endwise movement of said sleeve in one direction while the gear 52 is secured to the opposite end of the sleeve and engages the adjacent end of the bearing 59 to hold said sleeve against endwise movement in the o posite direction, said gear 52 being loclied to the sleeve by a screw pin -72- which also enters a key way "73* in the spindle 69 to allow the latter to be adjusted endwise relatively to the clamping head -65-to hold or release the lenses which may be clamped between said heads. The end of the spindle --69 adjacent to the-clamping head *"67 is enlarged forming an annular shoulder 74 upon which the acent end of the sleeve .70 is closely fitted with a sliding fit while the opposite end of said sleeveis similarly fitted upon the reduced portion of the spindle leaving the intermediate portion of the sleeve of somewhat greater diameter than the inclosed portion of the spindle for the reception of a coil spring -75 having its opposite ends interposed between the annular shoulder -74- and opposite end of the sleeve for the purpose of iorcingthe spindle -69 and its clamping head 67 endwise toward the clamping head -65- thereby clamping the lens or lenses between the heads 67- and 65-- under a yielding pressure. The tension-oi thisspring 75 may be varied at will at any time while the machine is at rest or during the operation-of grinding by means of a hand nut -76- which is coaxial with thespindle -69 and is screwed upon a fixed threaded hub -78 as best seen in Fig. 6, said spindle beingextended through the hub "78- andinto the hand nut 76-- and is provided at its outer end with an annular shoulder -79 which engages an internal annular shoulder -80 on the hand. nut 76-, suilicient space be ing left between'the annular shoulder 79 and adjacent end of the hub 78 to allow a limited endwise movement of the spindle in the hub and also in the sleeve 70 The annular shoulder 79 preierablyconsists of a washer which is detachably secured to the adjacent end of the shaft or spindle 69 by means of a screw -82 which when removed permits the removal of the washer 79 and also enables the hand nut -76 to be detached or unscrewed from the hub 73.

It is now obvious that when it is desired to place a lens or lenses between the clamping heads it is simply necessary to press the head 67 and its supporting spindle 69 back or against the action .of the spring 75 by hand and suflicient to permit the lens or lenses to be properly placed between the clamping heads, and when said lens or lenses are so placed the clamping head -67 and spindle 69 may be released to allow the spring -75 to force the spindle and its clamping head 67 toward the opposite clamping head 65 thereby clamping the lenses in place under a yielding pressure.

It will be evident from the foregoing description that the s indles 60 and 69 are separately ut positively driven by the pinions 50- and 53 meshing with their

respective gears

52 and 54 which latter are of the same pitch diameter and therefore the spindles are.

driven at the same rate of speed.

The upper portion of the swinging frame 56 upon which the

spindles

60 and 69 are mounted is movable toward and from the front face of the grindstone 3 and is drawn rearwardly by means of a coil spring -86 having one end attached at -87 to one of the bearings as the bearing 58 while the opposite end is attached to the upper end of an upright lever 89 which is fulcrumed at -90 intermediate its ends and having its lower end connected by a cord or cable 91 to a rotary drum 92. This drum is secured to and forms a part of a rotary adjusting spindle 93 which is journaled with a comparatively tight friction fit in the front part of the frame 1 preferably in'the lower side of the bearing 55 and is provided with a hand piece 94 by which it may be rotated in one direction or the other to wind or unwind the cord or cable 91 thereby operating the lever -89 to vary the tension of the spring 8G and permitting the edges of the lens to be forced against the grinding face of the grindstone with more or less pressure as may be desired. The means for rocking the frame 56 in the opposite direction against the action of the spring -86 to force the lens holder away from the grindstone and thereby throw the lenses out of engagement with the grindstone consists of the lever 37 which is located just at the rear of and engages the bearing 59 so that when the lever 37 is-drawn forwardly by hand it will engage the rear face of the bearing 59 and thereby rock the upper portion of the frame V56 forwardly against the action of the spring 86, said frame being locked in operative position by a detent or shoulder 98 which interlocks with a corresponding shoulder -99- on the rear side of the bearin 59 as best seen in Fig. 5. As previous y stated, when the lever 37 is rocked forwardly in the manner just described to throw the lens holder and its supporting frame 56 to its inoperative position, the driving mechanism which rotates the lens holder is simultaneously thrown out of action through the medium of the link 39 and its connection with the lever 40 and clutch element 21 and in order that the clutch may be connected and disconnected to the driving element 14 at the limit of movement of the lens holder and its sup orting frame toward and from the grin stone, the head 43 is provided with shoulders 43 which are spaced some distance apart at opposite sides of the adjacent end of the lever 40- with which they are adapted to engage as the link 39 is reciprocated backwardly and forwardly by the action of the lever37. In otherwords, when the lever is thrown forwardly to force the lens holder away from the grindstone the rear shoulder 43 en ages and operates the lever 40 to t row the clutch section 21 out of interlocking connection with the driving element 22 and when said lever is thrown rearwardly to allow the spring to draw the lens holder toward the grindstone, the forward shoulder 43 is similarly engaged with and operates the lever 40 to throw the clutch section -21 into operative engagement with the driving element 22, it being understood that during the retraction of the lens holder and its sup orting frame by the spring 86, the l ever 48 may be gradually released to allow the lenses to be drawn against the face of the grindstone under light pressure thereby avoiding any liability of cracking or breaking the lenses by undue force of contact.

The distance between the shoulders 43 on the head 43 is considerably greater than the width of the shoulders 98 and -99- on the lever 37 and bearing -59- respectively which permits the lens holder supporting frame to be released and swung rearwardly to bring the lenses into engagement with the grindstone without reengaging the clutch section 2l with the driving element 22. This operation is very often desirable to enable certain parts of the lenses requiring more grinding than other parts to be brought into engagement with the grindstone, and for this purpose the front end of the shaft 15 is extended forwardly and provided with a suitable hand wheel 100 by which the shaft and connection between it and the driving of the master pattern -64 may ride as 60 further means of adjustment for the back rest .101--, the rear end of the spindle 95-v spindle may be rotated by independently of the continuously rotating driving element -l4 or ,22 thus permitting to a certain sizeand form, the form correspending to that of the master pattern -64, I provide an adjustable bearing or stop 101.. against which the periphery the lens is ground to the desired size. This backrest or stop 101 as best seen in Fig. 7 is removably secured to the upper end of an upright support -102 and is located in a plane coincident with a line drawn between the axis of the grindstone shaft and lens holder, its contact face being substantially concentric with the axis of,

and of a radius corresponding nearly to that of the grindstone and both its front and rear end'are preferably of the same form so that it may be reversed or its ends interchanged for contact with the master pattern. The support 102- for the back rest 101 i is adjustable forwardly and rearwardly to vary the position of the contact face of said back rest thereby affording means for grinding lenses to different sizes, said support being held from lateral displacement by 1 and is guided upon a suitable fixed guide +103 on the main supporting frame or bed 1 while its lower end is mounted -104- and is provided with an annular shoulder 105 forming an abutment for one end of a coil spring 106 which surrounds the intermediate portion of the spindle within the bearing 104, the opposite end of said spring abutting against the adjacent end of asleeve 107 which is fitted in the outer end of the bearing 104-. This spindle is provided with a threaded outer end 108.- which is engaged by a hand rotated nut 109, the latter being provided with a series of graduations correspending to different sizes of lenses and movable into registration with a fixed graduation on the adjacent portion of the bearing 104, the rotation of the nut 109 serving to move the support -102 and back rest 1OS forwardly or rearwardly a predetermined distance according to the direction of rotation of the nut 109-, the

amount of adjustment and size of the lens being determined by the graduation on the nut which may be brought into registration with. the fixed graduation 110. As a is threaded and screwed into a threaded aperture in the lower end of the support 1O 2 and the front end of said spindle is extended through the nut 10-9 and provided with a suitable hand piece -112- which mits the back piece to be adjusted to conform to the graduations on the adjusting nut -109, the spring 106- serving to force the spindle rearwardly, thereby holding the nut l09- in frictional contact with the adjacent end of the bearing -104.

The operation of my invention is as follows, assuming that the grindstone is in ac tion or being rotated by any available source of power, not shown, but connected to the pulley, the lens holder is drawnbackwardly against the action of the spring -86- by the lever 3 7 to the position shown in Fig. 2. in which the clutch section -21-is thrown out of action and the lens supports are at rest whereupon the lens or lenses are placed between and closed by the lens holder in the manner previously described andthe back rest 1()1 is then adjusted to give the finperished lens the desired size as indicated by the v graduations upon the nut -l09. The lever v37 is gradually thrown backwardly by hand allowing the spring 86 to draw the lens holder and its supporting frame rear wardly to bring the edge of the lenses into engagement with the periphery of the grind stone. When the edges of the lenses are thus brought into contact with the grindstone, the lever 37 is further shifted rearwardly to bring the forward shoulder 43'into engagement with the upper end of the lever 40 thereby rocking the lever and forcing the clutch section 21 into 0 erative engagement with the continuous y rotating driving element -22 whereupon rotary motion will be instantly transmitted to the lens holders and lenses through the medium of the shaft 15 and gears -20, 50- and 52 and also the gears -53 and 54.- to the spindles 60 and -69 thereby rotating the lenses in the direction indicated by the arrow M-, Fig. 2 while the grindstone is rotated in the direction indicated by arrow N-. The operation of grinding now takes place and continues until limited by the engagement of all points in the periphery of the master pattern 64- with the ack rest or limiting stop 101.

If for any reason certain portions of the periphery of the lenses need more grinding than others the lever 37 may be rocked forwardly sufficient to throw the clutch 2 1 out of action thereby stopping the rotation of the lens holder and permitting such rotation to be effected through the medium of the hand piece --100 as previously described.

What I claim is: 1

1. In a lens grinding machine, a rotary grindstone, and a rotary lens holder comprising coaxialrotary spindles, one of said spindles having projecting pins, a lens pattern having apertures receiving said pins and removable therefrom, and a lens clamping head also provided with apertures receiving said pins and removable therefrom independently of the lens pattern.

2. In a lens grinding machine of the class described, a rotary axially movable grindstone, a rotary lens holder and support there for movable toward and from the .ace of the grindstone, an intermediate shaft forming part of the mechanism for transmitting motion from the grindstone shaft to the lens holder, means including a clutch for transmitting motion from the grindstone shaft to the intermediate shaft, additional means actuated by the grindstone shaft for moving said shaft axially when the clutch is in action and out of action, further means for transmitting motion from the intermediate shaft to the lens holder, and means for rotating the intermediate shaft to rotate the lens holder when the clutch is out of action.

3. In a machine of the class described, a rotary grindstone and supporting shaft therefor, a rotary lens holder, an intermediate shaft forming a part of a power transmitting mechanism between the grindstone shaft and lens holder, a rotary element loose on the intermediate shaft, means on the grindstone shaft for rotating said rotary element, a clutch for connecting and disconnecting said rotary element to and from the intermediate shaft, means for operating said clutch at will, and means for transmitting motion from the intermediate shaft to the lens holder.

4. In a lens grinding machine of the character described, a rotary grindstone and supporting shaft therefor, a rotary lens holder, an intermediate sh aft forming part of an operative connection between the grindstone shaft and lens holder, means movable inde pendently of the intermediate shaft for reciprocating the grindstone axially, means for connecting and disconnecting said last named means to and from the intermediate shaft, and additional means for transmitting rotary motion from the intermediate shaft to the lens holder.

5. In a lens grinding machine of the class described, a rotary grindstone and a supporting shaft therefor, a rotary lens holder, means actuated by the grindstone shaft for reciprocating the grindstone axially, additional means including a clutch for transmitting rotary motion from the grindstone reciprocating means to the lens holder, means operated at will for actuating the clutch, and means for rotating the intermediate shaft and lens holder connected thereto independently of the rotation of the grindstone when the clutch is shifted to its inoperative position.

6. In a lens grinding machine of the class described, a rotary and axially movable grindstone and supporting shaft therefor, an upright lever operatively connected to the end of the shaft, and means actuated by the rotation of thegrindstone shaft for operating grindstone axially, and further means for transmitting motion from the intermediate shaft to the lens holder.

8. In a lens grinding machine of the class described, a rotary and axially movable grindstone and supporting shaft therefor,a rotary lens holder, an intermediate shaft forming part of a mechanism for transmit ting motion from the grindstone shaft to the lens holder, a worm on the grindstone shaft, a worm gear loose on the intermediate shaft and meshing with said worm, a second worm rigid with said worm gear, a second worm gear meshing with the second Worm, a cam rotating with the second worm gear, an upright lever and engaged and reciprocated by said cam and connected to the grindstone shaft for reciprocating the latter axially, a clutch splined on the intermediate shaft and movable into and out of connection with the second worm, means operable at will for shifting the clutch, means for transmitting rotary motion from the intermediate shaft to the lens holder, said intermediate shaft being provided with a hand wheel by which it may be rotated to rotate the lens holder independently of the grindstone shaft when the clutch is thrown out of action.

9. In a lens grinding machine of the class described, a rotary grindstone and supporting shaft therefor, a rotary lens holder, a support for the lens holder movable to and from the face of the grindstone, a spring for forcing the lens holder support toward the grindstone, means including a clutch for transmitting motion from the grindstone shaft to the lens holder, a lever operable at will for forcing the lens holder support away from the grindstone, and additional means brought into action by the lever for-shifting said clutch.

10. In a lens grinding machine of the class described, a rotary grindstone and supporting shaft therefor, a rotary lens holder, a support for the lens holder movable to and from the face of the grindstone, a spring for forcing the lens holder support toward the grindstone, means including a clutch for brought into action by the lever for shifting said clutch, and'means on the lever for engaging the lens holder support and holding it in its inoperative position.

11. In a lens grinding machine of the class described, a rotary grindstone and supporting shaft therefor, a rotary lens holder and movable support therefor, means including a clutch for transmitting motion from the grindstone shaft to the lens'holder, a lever operable at will toforce the lens holder support away from the grindstone.

12. In a lens grinding machine of the class described, a grinding element, a rotary lens holder and supporting frame therefor movable toward and from the grinding element, a spring for drawing the supporting frame toward the grindstone, and a lever for engaging and forcing the lens holder supporting frame away from said element against the action of the spring.

13. In a lens grinding machine of the class described, a grinding element, a rotary lens holder and supporting frame therefor movable toward and from the grinding element,

a spring for drawing the supporting frame toward the grindstone, and a lever for engaging and forcing the lens holder supporting frame away from said element against the action of the spring, and means for locking the lens holder supporting frame in its inoperative position.

14. In a lens grinding machine of the class described, a rotary grindstone, a rotary lens holder, means for transmitting rotary mo- 0 tion from the grindstone to the lens holder including a clutch, a support for the lens holder movable toward and from the grindstone, a spring for drawing said support toward the grindstone, a lever for moving the support away from the grindstone against the action of said spring, and connections between said lever and clutch for throwing the latter out of action when said support is moved away from the grindstone.

5O 15. In a lens grinding machine of the class described, a rotary grindstone, a rotary lens holder, means for transmitting rotary mo- .tion from the grindstone to the lens holder including a clutch, a support for the lens holder movable toward and-from the grindstone, a spring for drawing said support toward. the grindstone, a lever for moving the support away from the grindstone against the action of said spring, and connections between said lever and clutch for throwing the latter out of action when said support is moved away from the grindstone, said lever having a limited movement independent of the clutch whereby the supporting frame for l the lens holder may be moved to bring the lens into engagement with the grindstone without throwing the clutch into action.

16. In a lens grinding machine of the class described, a rotary grindstone, a rotary lens holder, means for transmittin rotary motion '70 from the grindstone to the ens holder in:

cludin a clutch, a support for the lens holder movab le toward and from the grindstone, a spring for drawing said support toward the grindstone, a lever for moving the support away from the grindstone against the action of said spring, and connections between said lever and clutch for throwing the latter out of action when said support is moved away from the grindstone, said lever having a limited movement independent of the clutch whereby the supporting frame forthe lens holder may be moved to bring the lens into engagement with the grindstone without throwing the clutch into action, portions of the operating mechanism for the lens holder being operable independently of the grindstone when the clutch is out of action.

17. In a lens grinding machine, a grindstone, a rotary lens holder and swinging supporting frame therefor, a spring for drawing said frame toward the grindstone, a lever connected to the spring, a cable connected to the lever, and a rotar hand operated drum connected to the cab e for winding and unwinding the same and thereby operating the lever to vary the tension of the spring.

18. In a lens grinding machine, a grindstone, a rotary lens holder, a lens pattern coaxial and rotating with the lens holder, a back rest for the pattern adjustable toward and from the axis of said pattern, a support for the back rest provided with a threaded aperture, and a rotary threaded spindle engaged in said aperture for adjusting the support and back piece.

19. In a lens grinding machine, a grindstone, a rotary lens holder, a lens pattern coaxial and rotating with the lens holder, a back rest for the pattern adjustable toward and from the axis of said pattern, a support for the back rest provided with a threaded aperture, and a rotary threaded spindle engaged in said aperture for adjusting the support and back piece, a fixed indicator, and a rotary graduated nut mounted on the threaded portion of the spindle and having its graduations movable into registration with said fixed indicator, said nut operating to move the spindle endwise as it is rotated for adjusting the back rest.

20. In a lens grinding machine, a grindstone, a rotary lens holder, a lens pattern coaxial and rotating with the lens holder, a back rest for the pattern adjustable toward and from the axis of said pattern, a support for the back rest provided with a threaded aperture, and a rotary threaded spindle engaged in said aperture for adjusting the support and back piece, a fixed indicator, and a rotary graduated nut mounted on the thread- In Witness Whereoi I have hereunto set my ed portion of the spindle and having its gradhand this 26 day of February 1908. uations movable into re istration With said fixed indicator, said nut operating tomove BENNETT 5 the spindle endWise as it is rotated for ad- Witnesses:

j usting the back rest, and a spring for moving SMITH A. HARRIMAN, the spindle in one direction. I C. H. ANNAN.