US2790272A - File sharpener - Google Patents

Description

April 30, 1957 c. HAGERTY ET AL FILE SHARPENER 2 Sheets-Sheet 1 Filed April 16, 1954 mp m . INVEN TOR. Char/es 1. Ha h/////d/r7 K United States Patent FILE SHARPENER Charies L. Hagerty, El Monte, and William K. Hagerty, Alhambra, Calif., assignors to Hagerty Manufacturing Co., Inc, a corporation of California Application April 16, 1954, Serial No. 423,678

10 Claims. (Cl. 5174) The invention relates to machinery and equipment used for sharpening files, particularly of the type used in metal finishing work, and, more specifically, to such machinery and equipment utilizing a grinding wheel, which may be brought into grinding engagement with file teeth capable of being sharpened by grinding action.

An object of the present invention is to provide a file sharpener of the character described which will produce a precise, high quality sharpening action, restoring dull files to essentially new condition, whereby files resharpsued by the present machine will not only do a better filing job and last much longer between sharpenings, but also may be resharpened a greater number of times than with previously used methods and machines, thereby afiording a much more efiiective, and at the same time an increased, file life.

Another object of the present invention is to provide a file sharpener of the character above, which is fully automatic and only requires the user to insert a file to be sharpened and to start the machine, after which the machine will take over completely and, without further manual labor or skill being involved, advance the file in rapid successive steps through the machine and provide in such steps a fast, precision and successive grinding of all of the file teeth.

A further object of the present invention is to provide a file sharpener of the character described, which is made up of a minimum number of sturdily formed parts, capable of giving completely trouble free, efiicient and precise operation throughout a very long, useful life.

Still another object of the present invention is to provide a file sharpener of the character above, which may be used with files having different spacing of the teeth, and wherein the machine will be self-adjusting to handle automatically such different files.

The invention has other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by said drawings and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawings:

Figure 1 is a side elevation of a file sharpener constructed in accordance with the present invention.

Figure 2 is a longitudinal cross section of the file sharpener illustrated in Figure 1, and is taken substantially on the plane of line 2-2 of Figure 3.

Figure 3 is a plan view of the file sharpener.

'Figure 4 is an enlarged cross sectional view, taken substantially on the plane of .line 4-4 of Figure 1.

Figure 5 is a cross sectional view, taken substantially on the plane of line 55 of Figure 4.

Figure 6 is a further enlarged fragmentary detail view of the file advancing and sharpening portions of the machine shown in operative engagement with the file teeth.

The file sharpener of the present invention, as illustrated in the accompanying drawings, is arranged for use with elongated files 6, such as used in the metal working and finishing fiel-d, sometimes referred to as vixen files, and which are characterized by a plurality of longitudinally spaced, transversely extending, arcuately curved teeth 7. As an important feature of the present invention, a grinding wheel 8 is incorporated in the machine and is provided with an annular grinding surface 9, having a radius of curvature substantially equal to the radius of curvature of the teeth 7, the Wheel being journaled and power driven for rotation about the center of such curvature, with the surface 9 moving substantially in the plane of rotation and arranged to be brought into grinding engagement with the arcuate upper face 11, adjacent the leading cutting edge 12 of the file tooth to be ground, such edge being formed by an undercut forward face or shoulder 13. Cooperating with the grinding wheel 8 is a carriage means 14 for the file, which functions to advance the file in successive steps to the grinding wheel, presenting in each step one of the teeth for engagement with the grinding surface '9, as above explained.

As here shown, the several parts of the machine are unitarily assembled and supported for coordinated action by an elongated box-like base or frame 16, having rectangularly related side Walls 17 and 18, and end Walls 19 and 21. An upwardly and horizontally extending arm 22, here fastened to side wall -17, adjacent end wall 21, carries a vertical bearing 23 journaling a shaft 24 for the grinding wheel 8, the arm locating the grinding Wheel in a generally horizontal plane over the upper ends 26 and 27 of the side walls, intermediate the end walls 19 and 21. Preferably the wheel 8 is detachably mounted, centrally thereof, on the lower end 28 of the shaft 24, between clamp washers 29 and 31, here secured by a nut 32 threaded onto the lower end of the shaft. An electric motor 33 is carried by the arm 22 with the motor shaft 34 vertically arranged in horizontally spaced parallel relation to the shaft 24, and is connected thereto by a belt 36 entrained around sheaves 37 and 38, secured to the upper ends of the shafts 24 and 34 respectively. A sheet metal shroud 35 may be mounted in protective covering relation to the sheaves 37 and 38 and belt 36, and is here shown supported on the motor 33 and vertical bearing 23 by brackets 40 and 45. v c

The aforementioned carriage means 14 for the file here consists of an elongated bed 39, whichis carried by the frame 16 and supports the file for longitudinal sliding action radially of the grinding wheel 8 and substantially parallel to the plane of rotation of the wheel, whereby the file may be fed in longitudinal steps, effecting the successive grinding of the file teeth. Longitudinal movement of the file is here effected in part by supporting the bed 39 for reciprocating motion, longitudinally 'of the bed and transversely to and from the grinding wheel, the transverse component of such motion being suflicient to cause an engagement and disengagement of the upper face 11 of the file tooth being ground with the grinding surface 3 of the wheel, and the longitudinal component of such reciprocating motion being somewhat greater than the longitudinal spacing between the teeth. Cooperating with this reciprocating rocking motion of the bed is a ratchet means 41, which functions to restrain a predetermined longitudinal movement of the file with the bed upon movement of the latter away from the wheel; i e.,' to the left as viewed in Figure 2, so as to hold the file tooth in precise engagement With the Wheel 8 while effecting a sliding of the tile on the bed, the ratchet means permitting movement of the file on the bed in a reverse direction; i. e., towards the wheel and to the right as viewed in Figure 2, whereby the file will be moved in steps towards the wheel, presenting in successive order the file teeth for engagement with the grinding surface 9 of the wheel.

The rocking motion of the bed 39 is effected by an eccentric means 42 connecting one end 43 of the bed to the frame 16, adjacent the end 21 thereof; and a crank means 44 connecting the eccentric to the motor 33 for imparting an oscillating motion to the eccentric which in turn produces the aforementioned longitudinally and transversely reciprocating rocking motion of the bed. The opposite end 46 of the bedis supported to cooperate with the eccentric and its drive in producing the desired motions by the provision on the bed of a downwardly inclined slide 47 which rests upon a horizontally extending roller 48, here mounted on a supporting pin 49 extending between and supported by the opposite side walls 17 and 18 of the frame. As will be best seen from Figures 2 and 3, the slide 47 is here struck out from the bottom of the bed as a tongue portion which is inclined downwardly in the direction of the bed end 46. A spring 51 may be connected between the end of the slide and the end wall 19 of the frame for maintaining a resilient connection between the bed and the frame.

The eccentric means 42 is here composed of a crank shaft 52, having its opposite ends 53 and 54 journaled for rotation in the side walls 17 and 18 and being formed with an intermediate throw 56, to which the bed 39 is attached by means of a bearing 57. The crank drive means 44 for the eccentric here includes an arm 58, fixed at one end 59 to the end 54 of the eccentric crank for rotation therewith, and having a connection at its opposite end 61 by a link 62 to a throw 63 on a crank 64, provided at the terminal drive end of a gear reduction transmission drive means 66, forming part of and furnished as a drive head on the lower end 67 of the electric motor 33.

As an important feature of the present construction, the eccentric and drive means for the bed is arranged so that the end 43 of the bed travels upwardly and forwardly toward the opposite end 46 of the bed, and contrariwise, the bed end 43 travels downwardly during its movement toward the opposite end 21 of the frame. Cooperating with this movement of bed end 43, the cam slide 47 causes the bed end 46 to elevae slightly as the bed end 43 lowers and moves towards the frame end 21, and

contrariwise, the bed end 46 lowers slightly as the bed moves toward frame end 19; i. e., to the left as viewed in Figure 2, and while the opposite bed end '43 is elevating. At the end of the stroke of the bed to the left, as viewed in Figure 2, the bed end 43 raises and the bed end 46 lowers to approximately the same elevation. At the opposite end of the stroke; i. e., upon movement of the bed longitudinally to the right, as viewed in Figure 2, the bed end 43 is somewhat lower than bed end 46, so that the bed generally inclines upwardly from end 43 to end 46.

The ratchet means 41 here includes a movable dog, composed of an elongated rod-like member 71, hingedly secured adjacent one end 72 for swinging vertical movement of its opposite end 73 upon the file teeth 7. .As here shown, the end portion 72 of the rod 71 is threaded through a .pin 74, journaled at its opposite ends 76 and 77 in bearing lugs 78 and '79, mounted on the upper surfaces 26 and 27 of the frame side walls 17 and 18, thereby providing a pivotal connection for the end portion 72 about a transverse horizontal axis, and further providing a convenient .means for manual adjustment of the rod longitudinally of the bed, to effect a precise indexing of "the file tooth being held with the grinding wheel. A lock nut 75 may be provided on the threaded rod end for securing the same in adjusted position.

The opposite end portion 73 of the rod is preferably formed as a downwardly curved and transversely fiattened form, presenting a relatively sharpened forwardly and downwardly inclined leading edge 81 for engagement with the file teeth, and the forward portion of rod '71 is desirably provided with a swivel connection 82, so that edge 81 may be always horizontally transversely positioned for engagement with the file teeth 7, regardless of the rotated position of the rod in effecting desired longitudinal adjustment of its threaded connection to the pivot pin 74-, In the operation of the ratchet means, the rod end 81 will ride up and over the inclined upper face 11 of the file teeth upon movement of the bed in the direction of the frame end 21; i. e., to the right as viewed in Figure 2. Upon riding over the leading edge 12 of the tooth, the ratchet end 81 will fall into the trough 83 between the file teeth, and on the return stroke of the bed; i. e., to the left as viewed in Figure 2, the ratchet end 81 will engage the vertical face 13 of the tooth and hold the file against traveling with the bed, thereby causing the bed to slide longitudinally to the left under the file, so that on the return stroke of the bed the file will advance with the bed while the detent member again rides over the inclined face 11 of the file tooth. While the detent end 81 is engaged with tooth face 13, the bed raises upwardly, as above described, so as to bring the grinding surface 9 of the wheel into grinding engagement with the top face of the underlying file tooth. Upon completion of the grinding operation, the bed lowers away from the grinding wheel and moves in the direction of the grinding wheel, so that upon the ensuing return stroke the file will have been moved longitudinally an increment of length exactly corresponding to the longitudinal spacing between the file teeth, and thus present the next longitudinally adjacent tooth for grinding engagement with the stone.

In accordance with the present invention and as a particularly important feature thereof, the detent member 71 is of a length and is positioned so that the forward end 81 thereof engages the face 13 of the very tooth to be ground. in this manner, there is a precise indexing of each tooth with respect to the grinding surface 9, wherein the file tooth is positively locked in relation to the grinding surface while being ground, independent of and regardless of any minor variation in longitudinal spacing between the teeth. Also, this feature of the invention enables the machine to be automatically self-adjusting to files having different longitudinal spacing of the teeth. Files of the character arranged to be sharpened by the machine will have a nominal tooth spacing of seven or eight teeth to an inch. However, as explained, the machine will handle other variants. Preferably, the detent member 71 is mounted to one side of center, as viewed in plan in Figure 3, so as to engage properly the file teeth at openings 86 and 87, normally provided at the opposite ends of the files.

Preferably, means is provided for controlling the frictional resistance to the sliding action of the file on the bed, so as to insure the movement of the file with the bed during that portion of the alternating cycle that the file is advanced to the wheel. As here shown, the bed is constructed of channel shape, having opposed side flanges 88 and 89 for confining the opposite side edges 91 and. 92 of the file'for longitudinal sliding action on the bed, and .a plurality of flat leaf springs 93 are provided on the inside face of flange 89, preferably on opposite sides of the grinding wheel 8, for resilient engagement with the adjacent .file edge 92, for constantly urging the opposite file edge 91 into abutment with the inside face of flange 88 to insure a precision movement of .the file, and, additionally, to provide a controlled frictional resistance to the sliding of the file on the bed. As will .be seen in Figure 3, :the wheel 8 has a direction of rotation also urging the file solidly against the flange 88. .As a further feature, the provision of these springs enables slightly different widths.

As another feature of the present invention, the machine utilizes a grinding wheel of inverted cup shape having a depending peripheral rim portion 96, which here provides the grinding area 9, and enables such grinding area to enter between the teeth to grind effectively the top surfaces of the teeth. More specifically, such rim portion is beveled at its lower outside cornerto provide an annular, inclined grinding area, the plane of the inclined area, when viewed in cross section as seen in Figures 2 and 6, being substantially parallel to the top face 11 of the tooth 7 to be ground. Also, as will be seen from Figure 2, the plane of the wheel 8 inclines downwardly toward the forward end 19 of the machine, so that the plane of rotation of the grinding area 9 and the plane of the bed converge toward the front end of the machine. By reason of this important relationship, the aforementioned rocking movement of the bed effects upon the upward and forward grinding stroke of the bed a movement of the bed into substantial parallelism with the plane of rotation of the wheel, whereby the grinding action will be initiated at the central portion of the tooth being ground and will progressively; continue outwardly to the opposite ends of the tooth as the bed rises and inclines into a parallel position with respect to the wheel. The tilting of the plane of rotation of the wheel also insures the clearing of the fileteeth from the underside of the wheel during the return stroke of the bed.

Preferably, and as a further feature of the present invention, the grinding wheel 8 and its shaft 24 are mounted in the bearing 23 for axial displacement of the wheel, i. e., to and from the file supporting bed, so that a grinding engagement between the wheel and the tooth being ground may be maintained during a portion of the upward or transverse movement of the bed during the grinding cycle. Preferably, the axial displacement of the wheel is esiliently controlled, and, so that the Wheel will be normally maintained at an operating center insofar as its axial displacement is concerned, opposed helical springs 97 and 98 are mounted in mutual compression about the shaft 24 on opposite sides of the bearing 23. Spring 97 is compressed between the upper side 99 of the bearing 23 and the sheave 37. The lower spring 98 is compressed between the underside 101 of the bearing 23 and the washer 29, securing the wheel 8.

In the operation of the machine, the user need only insert a file 6 to be sharpened, onto the bed 39 at the forward end thereof, and slide the file toward the rear end of the bed until the detent edge 81 drops over the first tooth to be sharpened. The machine may then be started by energizing the electric motor, and thereafter the machine will take over completely and automatically advance the file in rapid successive steps, providing in each step for a fast and precision grinding of one of the teeth until all of the teeth have been ground. Thereafter the motor may be turned off and the sharpened file removed. The usual file of the character described is provided with teeth on its opposite sides, and where such files are sharpened in the present machine, the file is merely turned over after sharpening the teeth on the one side to effect a sharpening of the teeth on the other side. Each of the aforementioned steps is made up of two principal strokes of the bed. On the grinding stroke the bed moves upwardly and forwardly and into general parallelism with the plane of rotation of the grinding wheel. In this stroke, the detent 71 engages the forward vertical face 13 of the tooth being ground, and precisely indexes this tooth with respect to the grinding wheel, whereby the tooth and Wheel are positively locked in interengaged grinding relation. During this forward and upward stroke, the upper face 11 of the tooth being ground travels slightly across the grinding area 9, and this latter movement, coupled with the general rocking movement of the bed,

produces a somewhat round, convex shape on the face 11 behind the leading cutting edge 12, so as to better support and strengthen this edge. At ,the same time,-";the-

travel of the tooth across the grinding surface. 9 during the grinding action increases the length of the work area of the grinding wheel 8 and, consequently, its life. From time to time the grinding surface 9 of the grinding wheel 8 may be redressed as required.

We claim: g

1. A sharpener for files of elongated form having long'itudinally spaced transversely extending arcuately curved teeth comprising, a grinding wheel having an annular grinding surface with a radius of curvature substantially equal to the radius of curvature of said teeth and being journ-aled for rotation about the center of said curvature with said surface moving in substantially the plane of rotation, motor means for rotating said wheel, an elongated bed for supporting said file for longitudinal sliding action thereon positioned substantially parallel to said plane of rotation of and extending radially from said wheel for feeding said file along said bed for grinding said teeth, means supporting said bed for and causing reciprocating motion longitudinally of said bed and transversely to and from said wheel, the transverse component of said motion being sufiicient to engage and disengage said file teeth with said wheel surface and the longitudinal component of said motion being somewhat greater than the spacing between said teeth, and means restraining a predetermined longitudinal movement of said file with said bed in a direction away from said wheel to effect sliding of said file on said bed while permitting movement of said file on said bed in a reverse directionto thereby move said file in successive steps toward said wheel and presenting in each step one of said teeth for engagement with said grinding surface.

2, A sharpener for files of elongated form having longitudinally spaced transversely extending arcuately curved teeth comprising, a grinding wheel having an annular grinding surface with a radius of curvature substantially equal to the radius of curvature of said teeth and being journaled for rotation about the center ofs aid curvature with .said surface moving in substantially the plane of rotation, motor means for rotating said wheel, an elongated bed for supporting said file for longitudinal sliding action thereon positioned substantially parallel to said plane of rotation and extending radially from said wheel for feeding said file along said bed for grinding said teeth, means supporting said bed for and causing reciprocating motion longitudinally of said bed and transverselyto and from said wheel, the transverse component of said motion being sufiicient to engage and disengage said file teeth with said wheel surface and the longitudinal component of said motion being somewhat greater than the spacing between said teeth, and means positioned for engagement with the L tooth to be ground for restraining the longitudinal movement of said file with said bed in a direction away from said wheel to effect sliding of said file on said bed while permitting movement of said file on said bed in a reverse direction thereby moving said file in successive steps toward said wheel and in each step indexing the tooth to be ground in predetermined relation to said grinding surface.

3. A sharpener for files of elongated form having longitudinally spaced transversely. extending arcuately curved teeth comprising, a grinding wheel having an annular grinding surface with a radius of curvature subtantially equal to the radius of curvature of said teeth and being journaled for rotation about the center of said curvature with said surface moving in substantially the plane of rotation, motor means for rotating said wheel, an elongated bed for supporting said file for longitudinal sliding action thereon positioned substantially parallel to said plane of fotation and extendingflradially from said wheel for feeding said file along said bed for. grinding said teeth, means supporting said bed for and causing reciprocating motion longitudinally of said bed and transimely to and from said wheel, the transverse component of said motion being sufficient to engage and disengage said file teeth with said wheel surface and the longitudinal component of said motion being somewhat greater than the spacing between said teeth, and ratchet means in eluding a movable dog positioned to engage the file tooth to be ground and functioning to hold said tooth against said wheel surface and against longitudinal movement with said bedduring the transverse and longitudinal movement of said bed away from said wheel thereby causing the grinding of said tooth and the simultaneous sliding of said file on said bed, said ratchet means permitting movement of said file with said bed in the longitudinal movement thereof towards said wheel thereby causing said file to move in successive steps toward said wheel and presenting in each step one of said teeth for engagement with said grinding surface.

4. A- sharpener for files of elongated form having longitudinally spaced transversely extending arcuately curved teeth comprising, a grinding wheel having an annular grinding surface with a radius of curvature substantially equal to the radius of curvature of said teeth and being journaled for rotation about the center of said curvature with said surface moving in substantially the plane of rotation, motor means for rotating said wheel, an elongated bed for supporting said file for longitudinal sliding action thereon positioned substantially parallel to said plane of rotation and extending radially from said wheel for feeding said file along said bed for grinding said teeth, means supporting said bed for and causing reciprocating motion longitudinally of said bed and transversely to and from said wheel, the transverse component of'said motion being sufiicient to engage and disengage said file teeth with said wheel surface and the longitudinal component of said motion being somewhat greater than the spacing between said teeth, means restraining a predetermined longitudinal movement of said file with said bed in a direction away from said wheel to efiect sliding of said file on, said bed while permitting movement of said file on said bed in a reverse direction to thereby move said file in successive steps toward said Wheel and presenting in each step one of said teeth for engagement with said grinding surface, and means providing a controlled frictional resistance to said sliding of said file on said bed.

5. A sharpener for files of elongated form having longitudinally spaced transversely extending arcuately curved teeth comprising, a grinding wheel having an annular grinding surface with a radius of curvature substantially equal to the radius of curvature of said teeth and being journaled for rotation about the center of said curvature with said surface moving in substantially the plane of rotation and being supported for axial displacement of said wheel,.motor means for rotating said wheel, an elongated bed for supporting said file for longitudinal sliding action thereon positioned substantially parallel to said plane of rotation and extending radially from said wheel, for feeding said file along said be for grinding said teeth, means supporting said bed for and causing reciprocating longitudinal movement and transverse movement axially of said wheel, the transverse component of said movement being sufficient to engage and disengage said file teeth with said wheel surface and the longitudinal component of said movement being somewhat greater than the spacing between said teeth, means restraining a predetermined longitudinal movemerit of said file with said bed in a direction away from said wheel to effect sliding of said file on said bed while permitting movement of said file on said bed in a reverse direction thereby moving said file 'insuccessive steps toward. said wheel and in each step presenting one of said teeth for engagement with said grinding surface, and resilient means connected to said wheel and permitting resiliently yieldable axial displacement thereof by the file tooth being ground during said transverse movement for maintaining grinding engagement between said surface and said tooth during a portion of said transverse movement.

6. A sharpener for files of elongated form having longitudinally spaced transversely extending arcuately curved teeth comprising, a grinding wheel having an annular grinding surface with a radius of curvature substantially equal to the radius of curvature of said teeth and being journaled for rotation about the center of said curvature with said surface moving in substantially the plane of rotation, motor means for rotating said wheel, an elongated channel shaped bed for supporting said file and having opposed side flanges for confining the opposite side edges of said file for longitudinal sliding action on said bed, said bed being positioned substantially parallel to said plane of rotation and extending radially from said wheel for feeding said file along said bed for and causing grinding said teeth, means supporting said bed for reciprocating movement longitudinally of said bed transversely to and from said wheel, the transverse component of said movement being sufficient to engage and disengage said file teeth with said wheel surface and the longitudinal component of said movement being somewhat greater than the spacing between said teeth, means restraining a predetermined longitudinal movement of said file with said bed in a direction away from said wheel to effect sliding of said file on said bed while permitting movement of said file on said bed in a reverse direction to thereby move said file in successive steps towards said wheel and presenting in each step one of said teeth for engagement with said grinding surface, and a spring carried by one of said flanges and resiliently engageable with one side edge of said file for positioning the opposite side edge of said file against the other flange and providing a controlled frictional resistance to said sliding of said file on said bed.

7. A sharpener for files of elongated form having longitudinally spaced transversely extending arcuately curved teeth comprising, a frame, a grinding wheel rotatably carried thereby and having a concentric grinding surface with a radius of curvature substantiallyequal to the radius of curvature of said teeth, a motor carried by said frame and connected to said Wheel for effecting rotation thereof, an elongated bed for supporting said file for longitudinal sliding action thereon, eccentric means conneeting said bed to said frame for positioning said bed substantially parallel to the plane of rotation of said wheel and extending radially from said Wheel for feeding said file along said bed for grinding said teeth, said eccentric means supporting said bed for reciprocating longitudinal movement and transverse movement to and from said wheel for engaging and disengaging saidfile teeth with said wheel surface, crank means connecting said bed to said motor for imparting said movement to said bed, and means restraining a predetermined longitudinal movement of said file with said bed in a direction away from said wheel to effect sliding of said file on said bed While permitting movement of said file on said bed in a reverse direction to thereby move said file in successive steps toward said wheel and presenting in each step one of said teeth for engagement with said grinding surface.

8. A sharpener for files of elongated form having longitudinally spaced transversely extending arcuatcly curved teeth comprising, a grinding wheel mounted for rotation and having a concentric grinding surface in the plane of rotation and with a radius of curvature substantially equal to the radius of curvature of said teeth, a motor for rotating said wheel, an elongated bed for supporting said tile for longitudinal sliding action thereon and having an end extending radially away from said wheel with the planes of said bed and wheel surface convergently tapered toward said end, means supporting said bed for and causing reciprocating" rocking movement having a component longitudinally of said bed to providea longitudinal movement of said file and a component transversely of said bed to and from said wheel to engage and disengage said file teeth with said. wheel surface, said rocking movement providing upon movement of said bed in the direction of said wheel an orientation of said bed into substantial parallelism with the plane of said wheel surface whereby grinding action initiated at a central portion of the tooth being ground will continue outwardly to the opposite side ends of the tooth, and ratchet means engageable with said file teeth and coaacting with said rocking movement of said bed to advance said file in successive steps toward said wheel and presenting in each step one of said teeth for engagement with said grinding surface.

9. A sharpener for files having spaced arcuately curved teeth comprising, a grinding wheel journaled for rotation and having an annular grinding surface in the plane of rotation with a radius of curvature substantially equal to the radius of curvature of said teeth, motor means for rotating said wheel, a bed for supporting said file for sliding action positioned substantially parallel to said plane and extending radially from said grinding surface for feeding said file along said bed for grinding said teeth, means supporting said bed and wheel for and causing relative reciprocating motion radially of said grinding surface and transversely thereof, said transverse reciprocating motion being sulficient to engage and disengage said file teeth with said grinding surface, said radial reciprocating motion being somewhat greater than the spacing between said teeth, and ratchet means including a movable dog positioned to engage the file tooth to be ground and functioning to hold said tooth against said grinding surface and against motion with said bed radially of said grinding surface away from said wheel thereby causing a grinding of said tooth and a simultaneous sliding of said file on said bed, said ratchet means permitting movement of said file with said bed in the radial movement thereof toward said wheel thereby causing said file to move in successive steps toward said wheel and presenting in each step one of said teeth for engagement with said grinding surface.

10. A sharpener for files having spaced arcuately curved teeth comprising, a grinding wheel journaled for rotation and having an annular grinding surface in the plane of rotation with a radius of curvature substantially equal to the radius of curvature of said teeth, motor means for rotating said wheel, a bed for supporting said file for sliding action positioned substantially parallel to said plane and extending radially from said grinding surface for feeding said file along said bed for grinding said teeth, means supporting said bed for and causing a rocking reciprocating motion radially of said grinding surface and transversely thereof axially of said wheel, the transverse component of motion being sufiicient to engage and disengage said file teeth with said grinding surface, the radial component of motion being somewhat greater than the spacing between said teeth, ratchet means engaging the tooth to be ground and restraining movement of said file with said bed in a direction away from said wheel to effect sliding of said file on said bed during transverse movement of said bed to said grinding surface, said ratchet means permitting movement of said file on said bed in a reverse radial direction during transverse movement of said bed away from said grinding surface to thereby move said file in successive steps toward said wheel and presenting in each step one of said teeth for engagement with said grinding surface, and resilient means connected to said wheel and permitting resiliently yieldable axial displacement thereof by the file tooth being ground during said transverse movement of said bed to said grinding surface for maintaining grinding engagement of said surface and tooth during a portion of said transverse movement.

References Cited in the file of this patent UNITED STATES PATENTS 453,431 Schmaltz June 2, 1891 1,000,888 Beche Aug. 15, 1911 1,063,076 Simmons May 27, 1913 2,343,271 Anheuser Mar. 7, 1944 2,375,703 Swartzwelder May 8, 1945 2,627,143 Beyer Feb. 3, 1953' FOREIGN PATENTS 1,027,279 France Feb. 11, 1953

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