US2038682A - Machine for operating upon hides, skins, and leather - Google Patents

Description

April 28, 1936. G. A. SCHETTLER ,63

MACHINE FOR OPERATING UPON HIDE S, SKINS, AND LEATHER Filed 00t- 51, 1934 5 Sheets-Sheet 1 VENTOR @JSMI April G. A SCHETTLER 3 AND LEATHER SKINS,

Filed Oct. 31, 1954 MACHINE FOR OPERATING UPON HIDES,

3 Sheets-Sheet 2 /NVENTOR SKINS, AND LEATHER April 28, 19 36.

G. SCHETTLER MACHINE FOR OPERATING UPON HIDES,

3 Sheets-Sheet 3 Filed 001;. .31, 1934 /NVEN TO)? M a, 5%

Patented Apr. 28, 1936 UNITE STATES MACHINE FOB, OE'ERATING UPON HIDES, SKINS, AND LEATHER Gustav Adolf Schettler, Leeds, England, assignor to The Turner Tanning Machinery Company, Portland, Maine, a corporation of Maine Application October 31, 1934, Serial No. 750,795 In Great Britain November 1, 1933 14 Claims. (01. 149-16) This invention relates to machines for operating upon hides, skins, leather and other similar pieces of work. While the invention is illustrated as embodied in a grinder mechanism specially designed to sharpen a rotary cutter in a machine for shaving tanned skins, it will be understood that the invention and various important features thereof may have other applications and uses.

It is an object of this invention to provide a grinding attachment for sharpening tools which will be especially simple and compact in construction and highly efiicient in operation. It is a further object of the invention to provide a grinding attachment having a minimum number of parts subject to wear and liable to become loose, in order that lost motion and backlash in the traveling tool may be practically eliminated. Another object is to make such provision that, during travel of the grinder tool in sharpening operations, the operator may intervene to terminate the travel of the tool in either direction. By this arrangement a given portion of a new or damaged cutter may be given more attention than other portions, thus shortening the time necessary to sharpen the cutter tool as a whole. It is desirable also to insure that the grinder tool will remain in operation until it has cleared the cutter being sharpened by arriving at one end or the other of said cutter before the power means for rotating the grinder tool becomes inoperative, since by this arrangement there is considerably less likelihood of damage to either the grinder tool or the cutter undergoing treatment.

To these ends, and in accordance with an important feature of the invention, the grinder tool is arranged to be driven by an electric motor mounted on the carriage which carries the grinder tool in an organization wherein the said electric motor drives the means for moving the carriage from end to end of the cutter undergoing sharpening operations. There is thus provided an especially simple and compact mechanism which not only drives the grinder tool but moves it bodily along the length of the cutter to be sharpened. This unit of carriage, grinder tool, and electric motor are mounted, in the illustrated construction, upon a. slide having a supporting surface inclined toward the cutter to be sharpened and another surface at a relatively sharp angle to said supporting surface, the carriage having inverted V-shaped portion to fit over upon both of the described surfaces on the slide, the arrangement being such that said unit is maintained by gravity with the grinder tool in operative relation to the cutter once adjustment has been made of the tool with respect to the cutter. The wear on the co-operating supporting surfaces of the slide and carriage is relatively small. Moreover, whatever wear does take place 5 results in moving the carriage with itsgrinder tool toward the cutter undergoing treatment, which movement will be no more than is necessary to maintain proper operation of the tool due to wear of the latter in the grinding operation. 10 The point is that there is possible movement of the carriage and grinder tool in only one direction due to wear of the said supporting surfaces and hence the amount of looseness in the machine which might result in vibration and black- 1 lash is reduced to a minimum.

It is a further important feature of the invention that means is provided for insuring against injury to the grinder tool and to the cutter undergoing treatment through provision of means for 20 maintaining the grinder tool in operation until it has passed beyond the cutter at either end thereof although the operator may have initiated termination of sharpening operations, while the grinder tool is in contact With the cutter, through 25 proper manipulation of a member for starting and stopping the electric motor. By this means the operator may exercise control of the grinder mechanism at any point in its travel, the latter being thrown out of operation, however, only at 3 a safe point at one end or the other of its path of travel.

In the illustrated machine, the driving means. for the grinder carriage comprises a reversing clutch mechanism controlled by stop members adjacent the opposite ends of the supporting slide for the carriage, the said stops being arranged to co-operate with a, lever mechanism for reversing the movement of the carriage as the latter approaches each end of the slide. In order that the 40 operator may reverse the movement of the carriage at any point in its travel there is provided a manually operable member connected to the reversing mechanism so that the carriage may be instantly reversed in its direction of movement, thus shortening the travel of the grinder tool with respect to the cutter undergoing treatment and in this way facilitating conditioning of a new or damaged cutter, one portion of which may need more grinding than other portions.

These and other features of the invention and novel combinations of parts will nowrbe described in detail in the specification and then pointed out more particularly in the appended claims.

In the drawings,

the cylindrical knife or tool and the work supporting means broken away to expose the grinding angular or V-shaped guide attachment;

Fig. 3 is a plan view from above of the grinding attachment and adjacent parts of the machine;

Fig. 4 is a sectional plan view of the grinding attachment; 7 7 Q g Fig. 5 is a sectional elevationv of the reversing mechanism taken on line V-Vof Fig. 4;

Fig. 6 is a sectional elevation of the reversing mechanism taken approximately on line VIVI of Fig. 4;

' Fig. 7 is a sectional plan, taken on line VII-VII of Fig. 6, of a controlling member of the reversing mechanism in the neutral position; and

Fig. 8 is a sectional plan similar to Fig. 7 but showing the .controlling member in another position. 7 e 7 Figs. 5 to 8 are drawn to a larger scale than the remaining figures. 7 Referring t gs. 1 to 4, inclusive, of the drawings, in this particular'embodiment of the invention designed for use in leather shaving machines, there is provided, for carrying a grinding wheel or disc I in a readily removable manner to be hereinafter described, a saddle or carriage 2 consisting of a relatively heavy casting having a base 3 provided with an angular or'V-shaped guide 4 (Fig. 1) along one edge, the underside of the base being machined to provide a smooth surface or surfaces. This casting is mounted upon a slide 5 having'a machined upper surface transversely inclined and provided along its upper edge with a single V-way 6 which fits into the angular or V-shaped guide 4 onthe base of the saddle or carriage. The slide 5 is slidably mounted on the machine frame 1 in the rear of the knife or tool 8 so as to extend parallel to the axis of the knife or too-1 as shown in Fig. 3 with the surface inclined downwards at an angle of about 30 to the horizontal in a direction-from the rear of the machine towards the knife or tool as shown in Fig. 1. When the saddle or carriage is mounted on the slide its mass, acting under the influence of gravity, serves to maintain a good fit between the 4 and the V-way 6. The spindle 9 for the grinding disc or wheel I is mounted at one end of a housing 19 extending gcentrally across the base 3, and an electric motor II is mounted on one side of the housing at the other end thereof and in an opening in; said housing so that its spindle l2 extends into the housing iasshown inFig. 4.

beltdrive is provided for the grinding disc .01 wheel for which purpose a small pulley is'providedon the motor spindle l2 housing III, for reception of the driving belt :the housingi or wheel [projects from the housing I0 at the attached to the slide 5 I3 is mounted on the spindle 9 and a larger pulley l4 within the IS. The belt drive is thus enclosed. The housing may be closed atthe top by a cover l6 removably securedby dovetailed slots (orin any convenient manner) so as to provide access to the interior of When in position the grinding disc appropriate end as shown in Figs. 3 and 4.

, The travel of the grinding disc or wheel is effected by rack and pinion means, a rack I! being in a recess in the inclined face, anda pinion [8 being attached to a shaft l9 mounted in a bearing in a gear boxOl 9.3 56 20,

so as to enable the pinion Conveniently the electric reversing mechanism of a peripheral recess (Fig. 4)

see particularly Figs. 4 to 6, attached to the: base 3 of the saddle or carriage 2 adjacent to the housing slide 5, the pinion shaft l8 to mesh with the rack I? as shown in Fig. 1. motor II drives the pinion shaft medium of worm reduction gears 49 through the arranged in the gear box or case 2!). bevel 24 (Figs. 4, 5, and 6) of the reversing mechin association with'a flange or disc 25 keyed on the worm shaft 25 of the reduction gear is coupled to the motor spindle extends through the adjacent wall of the housing 59, and a reversing clutch 2B and opposed bevel gear box 20 is applied to the saddle 2 and the latter is mounted on the". 7

I9 is obliquely disposed.

l2 by a coupling 2'! which 22, 23 and a V the bevel gear'type both A driving 'anism is loosely mounted on the pinion shaft l9,

I shaft I9 for a purpose hereinafter set forth. A

on and in mesh with the driving bevel 24 as usual in reversing mechanism of this known type.

As regards the reversing mechanism, thefiange or disc 25 (Figs. 4 and 5) is shown of appreciable extent and is keyed on or formed with the pinion shaft i9, and the driving bevel 24, instead of being keyed on the shaft, is freely mounted thereon adjacent to the flange or disc 25 and furnished with a projection 34 arranged so as to extend into the recess 95 whereby when reversed, the bevel gear is permitted to revolve idly for part "of a turn,

i. e. before picking up the pinion shaft !9, so that r the movement of the slide is not reversed abruptly. Conveniently the bevel gear 24 is provided with two projections 94 constituted by studs or screws spaced at apart and the flange or disc 25 has two diametrically opposite peripheral recesses 95 each of rather more than 90 in extent for reception of the projections 94 so that the gear 24 is permitted to have about 90 of free movement in each direction. The'extent of the recesses may, of course, vary according to requirements. In this way there may be termed a time pick-up, as a short interval of time is allowed to elapse between the stopping of the traveling movement of the carriage 2 in one direction and the commencement of its movement in the opposite direction. This pause or dwell provides a smoother reversing action than is the case when the bevel gear 24 is keyed onthe pinion shaft [9, and obviates shocks on the mechanism. Alternatively, the flange ordisc 25 and the projections may be dispensed with and the bevel gear 24 may be keyed on the shaft.

The clutch 28 is shifted to engage it with one of the bevel pinions or theother as required, by means of a fork 32 (Figs. 5 and 6) pivotallyattached to a lever 33 also pivotally mounted freely on a shaft 34 rotatably mounted in the gear box or case 29. For operating the clutch fork lever .33 there is provided another lever 35 formed with spaced lugs 36 and rigidly fixed atone end on the same shaft 34 so that. the lugs embrace or straddie the clutch fork lever 33 as shown in Fig. 5. The

clutch fork operating lever 35 is acted upon at the other end, which is conveniently fitted with a cam roller 3? (Figs. 4 and 6), by a pointed plunger 38 slidably arranged in thegear box or case 29 formed with u is provided what in line with the dead centre of the clutch fork lever 33, as shown in Fig. 4, and urged towards the roller 31 by a spring 39 held in position by an adjusting sleeve 40. The lugs 36 on the lever 35 are spaced so that said lever passes over the dead centre in each direction of movement e. g. as shown in Fig. 4, before the appropriate lug thereon makes contact with the clutch fork lever 33, and the pointed plunger acts upon one side (see Fig. 4) or the other of the clutch fork operating lever 35, as the case may be, so that it tends to shift the clutch 28 in one direction or the other from its central or. neutral position. The purpose of this is to enable the travel mechanism for the grinder wheel I to be put into operation at the same time as the electric motor by a starting and stopping member common to both as will be described presently. To hold the clutch in neutral there is provided in the gear box or case 20 a spring-loaded bolt or detent 4| (Figs. 6, 7, 8) formed at one end for entrance into a notch 42 formed centrally in an opposing segmental portion 43 on the clutch fork lever 33, and this bolt or detent is operable to release the clutch fork lever 33 so that it is operated, under the action of the pointed plunger 38, to shift the clutch 28 into engagement with one or the other of the bevel pinions 29 and 30.

For reversing the motion of the saddle or carriage 2 automatically at each end of the stroke, the clutch operating shaft 34 is extended at one end so as to project from the gear box or case 2|) through an opening 44 (Fig. 6) in the base of the saddle or carriage 2 to the under side thereof, and a lever 45 (see Fig. 4) attached to the shaft at this end is connected by a link 46 with another similar lever 41 pivoted at one end on the under side of the aforesaid base 3 so that its free end, which may be fitted with a cam roller 48 (Fig. 4), is located in alinement with a pair of stops or abutments 49, 50 (see Fig. 3) spaced adjustably at a suitable distance apart lengthwise on the slide 5. As will be understood, as the saddle or carriage 2 approaches the end of its stroke in either direction of its travel, the said lever 41 engages and is turned by the corresponding stop, 49 or 59, so that the clutch member 28 is shifted from one of the loose bevel pinions 29, 30 to the other so that the motion of the saddle or carriage 2 is reversed. It will of course also be understood that at this time the aforesaid bolt or detent 4| is held inoperative, and that the spring-loaded pointed plunger 38 yields to allow the clutch fork operating lever 35 to pass from one side to the other of the dead centre.

Preferably and as shown, the motor II is started and stopped by means of a circuit breaker switch 5| (Figs. 3, 7, and 8). This switch 5| is mounted on the motor and it is found convenient to connector associate a contact member 52 thereof with the bolt or detent 4| so that, when the motor I is switched on, the bolt or detent is withdrawn and held inoperative, and when the said bolt or detent is released the motor is switched off. To this end, referring particularly to Figs. 3 and 4, as the motor is on the side of the housing l3 opposite to the gear box or case 29, the bolt or detent 4| is made long enough to extend transversely through the housing Hlfrom the gear box 23 towards the switch 5| (Figs. 4, 6, 7, and 8.) The bolt or detent 4| is slidably mounted in the wall of the housing H] opposite to the gear box 28 and has a compression spring 53 mounted thereon between the said wall of the housing It] and a collar 54. Conveniently the horizontally, for clearness. the arrangement is such that when the plunger switch 5| has a contact member 52 (Figs. 3, 7, 8)

The adjusting screw 55 is set so that its head is always in contact with the opposing end of the contact member 52; The movements of the contact member 52 and bolt or detent 4| are controlled by a manually operable plunger 56 having at one end a wedge 51 (Figs. 6 and '7) for en trance into a slot 58 in the bolt or detent 4|, and at the other end a handle or knob 59 for the use of the operator, said plunger being mounted in a suitable support 60 attached to the saddle or carriage 2 at right angles to the aforesaid bolt or detent. The inclined edge of the wedge 51 acts upon the periphery of a roller 6|, located in the slot on a pin 32 riveted in position, so as to facilitate withdrawal of the bolt or detent from the notch 42 in the clutch lever 33 against the combined action of the spring 53 and the spring (not shown) associated with the contact member 52. Actually the plunger 55 is obliquely disposed in relation to the gear box or case 29, as shown in Fig. l, but in Figs. 6 and '1 the wedge 51 and adjacent parts are drawn as though disposed Referring to Fig. 8,

55 is moved endwise, e. g. pushed down by the operator, the Wedge 5? acts upon the roller 6| so that the bolt or detent'is moved endwise, i. e. withdrawn from its operative position so as to enable the clutch member 28 to be engaged with either gear 29 or 30 as the result of the action of the spring-loaded plunger 38 on the roller 31 of the lever 35, .and at the same time the switch contact member 52 is operated i. e. pushed endwise correspondingly, to start the motor The grinding disc or wheel I is thus driven and' the travel of the same along the slide 5 commences.

As shown in Fig. 8 the engagement of the clutch member 28 with gear 29 or 30 also carries the aforesaid notch 42 out of register with the bolt or detent 4| so that the latter is opposed by the segmental portion 43 of the clutch fork lever 33 on one side or the other of the notch 42. At each end of the stroke of the saddle or carriage 2 the movement thereof is reversed by the mechanism provided as aforesaid and the action continues for as long as the operator wishes.

The operator can cause the stopping of the motor II at will by moving the plunger 56 in the opposite direction, e. g. pulling it out, at any time during the said travel of the carriage 2 but the motor will not be stopped until the grinding disc or wheel I is at one end or the other of its stroke according to the direction in which the saddle or carriage 2 is moving. That is to say, to stop the motor the operator moves the plunger 55 in such manner'that the wedge 51 is withdrawn from the slot 58 and consequently from contact with the roller 6| to such an extent as to leave the bolt or detent 4i and the contact member 52 free to move back to their original positions under the action of their springs. Such movement, however, does not occur until the reversing clutch 28 is next operated in the manner described and the aforesaid notch 42 (Figs. 7 and 8) is again brought into register with the bolt or detent 4 I. Thereupon the bolt or detent automatically enters the notch as shown in Fig. 7 thereby releasing the contact arm 52 (to switch off: the motor) and preventing further movement of the clutch 28 under the action of the spring-loadedpointed plunger 38. The arrangement is such that the'traveling movement of the disc or wheel I is not stopped until said disc or wheel has been carried clear of the knife crtool 8 at one end or the other. 7

A main switch 93 for the circuit of the motor 'I I, Figs. 1 and 2, mounted on one of the machine frame side members 1 at the back, has its contact member 64 connected to or with one' arm 65 of a lever pivoted on a bracket 66 attached to the main switch box and having another arm 61 located between spaced pins 68 on a member, such as a slide bar 99, mounted in the side members 1 adjacent to the switch, and connected with the mechanism employed for. starting and stopping the cylindrical knife or tool 8, so thatthe current is switched on and off accordingly. For example,

' the said operating member or bar 69 may form part of a beltshifting gear (not shown) arranged at the back of the machine and operable by means of a handle 69a at the rear of the machine to start power operation of a shaft 6% which fixedly carries pulley 69o around which passes belt 69d arranged to drive a pulley 69e'on the shaft of the rotary cutter 8. The pins or like projections 98 are so spaced from each other that the operating member or bar 69 has a certain amount of lost motion in relation to the switch lever 65, 61 before operating the latter when the starting handle 69a is moved, whereby said'tool 8 is placed in operation before the circuit of motor I I is energized.

Referring to Figs. 2 and 3, for moving the grinding disc or wheel I towards and from the tool 8 and adjusting the depth of cut, the slide 5 is movable on the top of the machine frame side members I by means of screws I arranged to turn without axial movement in V screw-threaded flanged sleeves, bushes or nuts 'II inserted fixedly into the slide at the back, and the latter is engaged by 'counterweighted bell crank levers I2 which act through the slide to press the sleeves, bushes or nuts in an axial direction on the screws for the purpose of eliminating backlash. The screws are rotatably mounted and prevented from axial movement in bearings 13, 13a fixed on the tops of the frame side members at the back of the slide so that the screws Ill extend at right angles to the length of the slide into the corresponding screwed members 'II. The counterweighted bell crank levers I2 are pivotally mounted at H on said side members I so as to engage a lengthwise extending rib I within or on the slide 5. The screws I0 may be rotated by means of worm or like gearing operable by means of a hand wheel, bevel gears, and shafts suitably arranged. Conveniently, a shaft I6 (Fig. 3) is mounted in bearings 5; provided on the bearings I3 and has at each end'a worm I8, I80. arranged so as to V mesh with a' worm wheel '19 fast on the adjacent screw 19 and for rotating the shaft I6 there is provided adjacent to one end thereof an obliquely disposed manually operable shaft 80 (Fig. 1) ex-- tending from front to rear of the machine at one end of the shaft I6, and bevel or mitre gears 8|, 82 respectively are provided on the rear end of the shaft 80 and on the adjacent end of the shaft IS. The shaft 89 is mounted in bearing 83, 84 and is furnished with a hand wheel 85 at the front end for rotating it. The bearing 83 is mounted on a bracket 86 extending upwardly from the frame 7 of the machine and the bearing 84 is provided on the adjacent bearing I3.

Means are provided in association with the reversing mechanism for the carriage 2 whereby the said mechanism may be operated manually to reverse the motion of the saddle or carriage 2 at any stage in its traveling movement. For exampla'in the particular arrangement hereinbefore described the shaft 34 on which the clutch fork operating lever 33 is mounted, is extended to the outside of the gear box or case 29 at the top and is formed or provided with means at that end to which a suitable tool, such as a key, spanner or tommy bar, can be applied so as to' enable it to be turned by the operator for the purpose stated, the effect being the same as that resulting from the action of one of the stops 49, 50 on the lever 41. For instance, as shown in the drawings, the shaft may have a square or like 7 end 360. for reception of a spanner.

Referring to Fig. 4, to enable the grinding disc or wheel .I to be readily placed in position and removed without disturbing the spindle 9, the latter is preferably fixedly mounted at one end onthe saddle or carriage 2, and has a flanged or shouldered hub 81 mounted rotatably thereon for the reception of the grinding disc or wheel, a washer 88, and a clamping nut, such as an internally screw-threaded ring 89, the hub being correspondingly'screw-threaded externally at one end to receive the nut. As shown the disc or wheel is secureiy held on the hub between the flange or shoulder 99 and the washer 88 by the clamping nut Be. A centre screw or poppet 9| is preferably provided for supporting the free end of the spindle so as to steady the samewhen the disc or wheel is rotating. Thus the disc or wheel can be readily placed on the hub and removed therefrom when worn, or changed for a different disc or wheel, simply by withdrawing the centre screw or poppet, removing the clamping nut 89 and washer 88, and slipping the wheel I on or off the hub 81 while the embodiment described and shown'in the drawings, the spindle 9 is fixedly mounted in one of the walls of the aforesaid housing I0 and the centre screw or poppet BI is provided in the opposite wall, the spindle 9 having a central recess 92 in the free end to receive the conical or pointed end of the screw or poppet 9|. The centre screw or poppet has a head 93 knurled or otherwise formed to facilitate movement thereof by the operator. In this construction and arrangement, after the centre screw or poppet 9 I has been withdrawn and the clamping nut 99 and washer 88 have been removed the disc or wheel I is passed between the end of the screw or poppet SI and V the spindle 9 when being applied to or removed from the hub. The hub 81 is preferably mounted on ball bearings and has combined therewith, or

' is attached to the pulley I3, for driving the disc or wheel. r r 7 An electric motor II of the single phase repulsion start induction type is found to be most suitable for driving the improved grinding atmounted in such a manner as automatically to eliminate backlash, so that vibration is avoided, and that the arrangement is self adjusting as regards taking up wear. Another important advantage is that the electric motor drive enables practically the whole of the driving mechanism for both rotating and effecting the traverse of the disc or wheel to be mounted on the saddle or carriage so that this constitutes a self contained unit adapted to be readily applied to and removed from the machine.

The provision of means whereby the operator can effect reversal of the motion at will,'i. e; at any stage in the traverse, is especially advantageous in connection with the grinding of new knives or tools as it enables portions which require more grinding than the remainder to be repeatedly operated upon without loss of time. Any suitable means may be provided for shielding the grinding attachment or mechanisms from shavings or other material removed from hides, skins, leather and the like by the knife or tool during working operations. Conveniently for this purpose curtains (not shown) of canvas or like material are suspended from a rod fixed adjacent to the saddle or carriage, and are attached to or acted upon by the saddle or carriage on the opposite sides of the grinding disc or wheel so as to be respectively extended and pleated as the saddle or carriage travels first in one direction and then in the other direction. V Practically the whole of the mechanism is enclosed so that it is well protected from metallic or other particles resulting from the grinding operations.

Having described my invention, what I claim as new and desire to secure byLetters Patent of the United States is:

1. In a grinder mechanism, a grinder tool, a carriage for the tool, a slide member for supporting and guiding said carriage, an electric motor mounted on said carriage and having connections to operate said grinder tool, and cooperating driving members mounted on the carriage and slide and arranged to be'driven by said motor to cause travel of the carriage along said slide during operation of said grinder tool.

2. In a grinder mechanism, a' rotary grinder tool, a carriage for the tool, a slide member for supporting and guiding said carriage, an electric motor mounted on said carriage, co-operating rack and pinion members mounted on the carriage and slide respectively, and connections between the motor as the source of power and said pinion member and rotary grinder tool whereby the latter are driven from the motor to cause simultaneously rotation of the grinder tool and travel of the carriage along said slide member to effect sharpening of a cutter during movement of the grinder tool lengthwise of said outter.

3. In a grinder mechanism, a grinder tool, a carriage for the tool, a slide member for supporting and guiding said carriage, an electric motor mounted on said carriage, co-operating driving members mounted on the carriage and slide and arranged to be driven by said motor to cause travel of the carriage along said slide member, said co-operating driving members comprising a reversing clutch member, a manually controllable member for initiating termination of the operation of said motor, said manually operable member being, operable at any point in the travel of said carriage, and a member for holding the switch operative to maintain the motor in operation until the carriage reaches a predetermined point in its path of travel.

4. In a machine having a cutter for treating hides, skins, leather and other similar pieces of work, a grinder tool, a carriage for supporting the grinder tool, and a slide member along which the carriage is moved to progress the grinder tool lengthwise of said cutter, said slide member having a carriage-supporting surface inclined toward said cutter and having further a guiding surface at a substantial angle to said-supporting 7 surface at the upper edge of the latter, and said carriage having surfaces arranged for co-operation with the surfaces on the slide member whereby the carriage is held by gravity with the grinder tool in working relation with respect to said cutter.

5. In a machine having a cutter for treating hides, skins, leather and other similar pieces of work, a grinder tool, a carriage for supporting the grinder tool, and a slide member along which the carriage is moved to progress the grinder tool lengthwise of said cutter, said slide member having a carriage-supporting surface inclined downwardly toward said cutter at an angle of about 30 to the horizontal and having further a guiding surface at a substantial angle to said supporting surface at the upper edge of the latter, said carriage having on its under surface an inverted V-shaped groove designed to co-operate with said supporting and guiding surfaces on the slide member whereby the carriage is maintained by gravity in contact with said supporting and guiding surfaces on the slide member irrespective of the amount of wear on said surfaces. 7

6. In a machine having a cutter for treating hides, skins, leather and other similar pieces of work, a grinder tool, a carriage for supporting the grinder tool, a slide member along which the carriage is moved to progress the grinder tool lengthwise of said cutter, said slide member having a carriage-supporting surface inclined toward said cutter and having further a guiding surface at a substantial angle to said supporting surface at the upper edge of the latter, said carriage having on its under surface an inverted V-shaped groove designed to cooperate with said supporting and guiding surfaces on' the slide member whereby the carriage is maintained by gravity in contact with said supporting and guiding surfaces on the slide member irrespective of the amount of wear on said surfaces, adjusting screw members engaging said slide, member and held from axial movement in bearings rigidly mounted on the machine frame, and a weighted member or members operating to press said carriage-supporting slide in a direction axially of the adjusting screw members so that there is no backlash between said slide and screw members.

'7. In a grinder mechanism, a grinder tool, a carriage for the tool, a slide member for supporting and guiding said carriage, an electric motor mounted on said carriage, co-operating driving members for the carriage mounted on said carriage and slide and arranged to be driven by said motor, said cooperating driving members comprising a reversing clutch member, a lever connected to said clutch member, and spaced stops on the slide member adjacent to the opposite ends thereof for engagement with saidv lever'as the" carriage approaches each end .of. the-slide mem,-.

bet to operate said lever to shift the clutchmem comprising a reversing clutch member, a lever to" shift the clutch member, a latch for locking said a 6 r V aossrsa ber, thereby to reverse the direction of movement of the carriage only after said grinder tool has passed beyond the corresponding end of a cutter undergoingsharpening treatment.

8. In a grinder mechanism, a grinder tool, a carriage for the tool, as'lidemember for supporting and guiding said carriage, an electric motor 'mounted on said carriage, I co-operating driving members for the carriage mounted on said carriage and slide and arranged to be driven by said motor, said cooperating driving members lever with the clutch member in neutral position,

a switch member for controlling the motor, and a manually operable member arranged to operate the latch and the switch so that said clutch member is freed for movement to clutching position 55 just prior to the starting of the motor.

9. In a grinder mechanism, a grinder tool, a carriage for the tool, a slide member for supporting and guiding saidcarriage, an electric motor mounted on said carriage, co-operatingdriving members for the carriage mounted on said car- 7 Triage and slide and arranged to be driven by said motor, said cooperating driving members comprising a reversing clutch member, a lever to shift the clutch member, a latch'for locking said I lever with'the clutch member in neutral position,

a switch member for controlling the motor, a manually operable member arranged to operate the latch and the switch so that said clutch member is freed for movement toclutching position just prior to the starting of the motor, and means for holding the switch in operative'or motor driving position until the carriage has moved the grinder tool to one end or the other of the slide member and beyondia cutter undergoing treatment. i f I V 10. In a grinder mechanism, a grinder tool, a carriage for'the tool, a. slide member for supporting'andguiding saidcarriage, an electric motor 'mounted on said carriage, co-operating driving members for the carriage mounted on said carriage and slide and arranged to be driven by said motor, said'cooperating driving'members comprising a reversing clutch member, a lever hav ing spaced lugsjtoengage said clutch member to shift the latter, a latch for locking said lever with'the rclutch'membeir in neutral position, a'

7 switch member for controlling the motor, a manually operable'member arranged to operate the latch and the switchso that said clutch member is freed for movement to clutching position just prior to the starting of the motor, and a cam surface associated with the clutch shifting lever and adapted to hold the'latchmember in nonlatching position until the carriage reaches one end or the other of its path of travel on said slide member, and said latch member when in non-latching positionbeing arranged to hold said switch in operative or motor-driving position whereby the grinder tool is driven and the car riagecontinues in movement until the grinder tool passes beyond one 'end of a cutter undergoing sharpening'treatment. V

, 11. In a grinder mechanism, a grinder tool, a carriage for the tool, a slide member for supporting and guiding said carriage, an'electric motor mounted on saidcarriage, co-operating driving members for the carriage mounted on said carriage'and slide and arranged to be driven by said motor, said cooperating driving members'coma reversing clutch member, a lever connected to shift said reversing clutch member, stops mounted on the slide member adjacent each end thereof to cooperate with said clutch, shifting lever toeffect shifting of said clutch member and V reversing of the direction of movement of said. carriage, a manually operable member to shift said clutch member whereby the operator may' effect reversal of the direction of movement of, the carriageat any point in the travel of the lat-- ter, and means to maintain said driving members in operation until the carriage travels to the point where'it was previously automatically reversed by the action of said lever and one of said stops.

12. In a machine for performing cutting opering said driving means, a switch for controlling 7' said motor, and a manually operable member for operating said starting member and having a lost motion connection with said switch whereby the tool to be, sharpened is put in operation before the grinder tool and carriage maybe moved by said motor. I V 7 13. In a grinder mechanism, a grinder tool, a

carriage for the tool, a slide member for supporting and guiding said carriage, an electric motor ,mounted on said carriage, cooperating driving members for the carriage mounted on said car-' riage and slide and arranged to be driven by said motor, driving connections between said motor and said grinder tool, a switch to start and stop said motor, a manually operable member to con-' trol said switch, and a latching member to hold said switch in operative or motor driving position after releaseof the switch by said manually operable member whereby said switch is maintained in motor-driving position until the grinder and carriage reach one end of the path of said car-:

riage on its supporting slide member. i

114. In a grinder mechanism, a grinder tool, a carriage for the tool, a slide member for supporting and guidingsaid carriage, an electric motor mounted on said carriage and arrangedto drive said grinder tool,co-operating driving members r for the carriage mounted on said carriage and slide and arranged to be driven by said motor, said co-operating driving members comprising'a reversing clutch member, a lever to shift said clutch member whereby the carriage'may be reversed in its direction of travel at each end of its path on said slide member, a yieldable member for holding the clutch shifting lever with the clutch member in engaging position, a latch mem;

ber for holding the clutch shifting member in neutral position a cam surface associated with said clutch shifting lever and adapted to hold said latch member in non-latching position, a switch for, causing operation of saidmotor, said latch member when in non-latching position serving to hold said switch'member, in its operative or motordrivingposition, and a manually operable member for moving said latch member to non-latching position and simultaneously therewith effecting movement of the switch member to motor-energizing position whereby the motor isstarted to effect travel of said grinder carriage.

GUSTAV ADOLF SCHET'I'LER."

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