CUTTING TOOL SHARPENING DEVICE

The present invention relates to the sharpening and/or honing of cutting edges and, in particular, provides a manual sharpening and/or honing guide.

Background Art

Many tools having a cutting edge require to be sharpened (or ground) from time to time in order to remove material and re-obtain a cutting edge. Honing is the refinement and final finishing of that edge and is carried out more frequently. Typically an edge will have one side flat and the other side sharpened at an angle of 25° to the flat. The sharpened area will be honed at an angle of 30° to the flat giving rise to a difference of 5° between the two bevelled surfaces. This difference in angle means that the width of the honed area is smaller than the width of sharpened area, thereby reducing the total area and time required to do the honing. In addition, the angle between the two surfaces means that the cutting edge is thicker, and thus stronger, than if only a single surface were used.

It is also known that some tools have cutting edges with both sides bevelled. Thus there are two sharpened areas and two honed areas. Such cutting edges, and skew tipped blades (including the blades of side-rabbet planes), are difficult to restore once they become blunt.

There are many devices to enable sharpening and/or honing, however, in order to prevent heating or burning of the cutting edge, resulting in an increase in temper and loss of hardness, it is desirable that motorised devices not be utilised. For this reason manual sharpening and/or honing is preferred.

Various devices to manually sharpen and/or hone cutting edges are known. US Patent No. 4,733,501 (Lee Valley Tools Ltd); US Patent No. 3, 950,899 (Stanley Tools Limited); Japanese Published Specification No. 10,044,001 A2 (Etsuro); Japanese Published Specification No. 62,136,355A2 (Harao); and Japanese Published Specification No. 10,337,641 A2 (Takanobu) are representative of this art. In this art the tool with the cutting edge is rolled backwards and forwards over a stationary

grindstone, oil stone or similar device with the tool and roller being positioned above the grindstone. This is disadvantageous since the cutting edge is obscured from view and the tool must be inverted if the progress of the grinding is to be observed. Such a movement runs the risk that the cutting tool will be dislodged or bumped relative to the rolling tool holder by the movement required to view the cutting edge.

Object of the Invention

The object of the present invention is to provide a manual sharpening and/or honing guide in which the cutting edge faces upwardly so that it can be inspected without having to move the cutting edge.

Summary of the Invention

In accordance with a first aspect of the present invention there is disclosed a manual sharpening and/or honing guide for moving a grindstone by reciprocating rolling motion relative to a cutting edge of an implement to be sharpened or honed, said guide comprising a holder for the implement having the cutting edge, said holder being adjustable with respect to a frame to set the sharpening or honing angle, and a roller mounted on said frame and arranged to be in rolling engagement with said grindstone, wherein said holder positions said cutting edge facing upwardly, and said grindstone is located above and in contact with said cutting edge and roller, extends therebetween to sharpen or hone said cutting edge, and whereby said grindstone is able to be lifted from said roller and cutting edge to permit said cutting edge to be inspected without moving said cutting edge.

hi accordance with a second aspect of the present invention there is disclosed a method of manually sharpening and/or honing the cutting edge of an implement.

Brief Description of the Drawings

One embodiment of the present invention will now be described with reference to the drawings in which:

Fig. 1 is a perspective view of the device of the preferred embodiment with a first tool holder,

Fig. 2 is a side elevation of the device of Fig. 1,

Fig. 3 is apian elevation of the device of Figs. 1 and 2,

Fig. 4 is an exploded perspective view of the device of Figs. 1-3,

Fig. 5 is a perspective view of the device of Figs. 1-4 but illustrating a different tool holder,

Fig. 6 is a front elevation of the device of Fig. 5,

Fig. 7 is a plan view of the device of Figs. 5 and 6,

Fig. 8 is an exploded perspective view of the device of Figs. 5-7, and

Fig. 9 is an exploded view of the device of Figs. 1-4 but illustrating a further tool holder.

Best Mode of Carrying out the Invention

As seen in Figs. 1-4, the guide 1 of the preferred embodiment has a frame 2 which takes the form of a horizontal base 3 and a vertical wall 4. As best seen in Fig. 4, a roller 6 extends horizontally from the wall 4 and a tool holder 7 is pivoted about a horizontal axis in the form of bolt 8. The wall 4 is provided with an arcuate slot 9 through which a threaded fastener 10 passes. A wing nut 11 enables the fastener 10 to be secured and thereby hold the tool holder 7 at an angle indicated on the scale 12 reproduced on the wall 4. The wing nut 11 can be substituted by a thumb screw or other type fastener and the scale 12 can be reproduced on both sides of the wall 4..

The tool holder 7 is provided with a pair of guides 14 and a clamping piece 15 which enables a cutting tool such as a plane blade 16 (Fig. 1) to be securely clamped to the tool holder 7.

As best appreciated from Fig. 1, the plane blade 16 prior to being clamped, can be advanced along the tool holder 7 so that the surface 26 which is inclined to the

longitudinal axis of the plane blade 16, and which forms the cutting edge 27, is substantially level with the upper edge of the roller 6. In this position a grindstone 20 can be supported by the surface 26 and the upper edge of the roller 6 and manually reciprocated backwards and forwards as indicated by arrow A in Fig. 1 so as to carry out the sharpening or honing as the case may be. The grindstone 20 moves the roller 6 in opposite directions as indicated by arrows B in Fig. 2. As mentioned above, typically sharpening is carried out with the tool holder 7 at an angle of approximately 25° whereas honing is carried out with the tool holder at an angle of approximately 30°.

The reciprocating motion of the grindstone 20 is intuitive and easily learned by the user. Furthermore, the surface 26 can be inspected easily at any stage during the sharpening or honing procedure in order that the progress of the procedure may be assessed. This is able to be done without in any way changing any of the settings of the device or even moving the plane blade 16. So there is no possibility of any setting being inadvertently bumped, knocked out of alignment, etc.

Turning now to Fig. 3, it will be apparent that the plane blade 16 has a longitudinal axis which is substantially perpendicular to the cutting edge 27 and its associated surface 26. Some implements such as chisels have a cutting edge which is inclined to the longitudinal axis of the implement itself. Such a cutting edge is able to be sharpened by mounting the implement with its longitudinal axis inclined to the requisite degree to the longitudinal axis of the tool holder 7 and then clamping the implement in position. In this connection, a person skilled in the art will appreciate that the clamping piece 15 of Figs. 1-4 can be replaced by equivalent pieces of different shapes in order to accommodate differently shaped implements.

With the foregoing description of the guide 1 in mind, it will be apparent to those skilled in the art that there are some implements such as gouges 30 (Fig. 5) which are provided with a curved cutting edge 127 and a correspondingly curved adjacent surface 126. In order to permit such implements to be sharpened, the tool holding arrangements illustrated in Figs. 5-8 are provided.

As best seen in Fig. 8, the tool holder 107 of the second embodiment is more complex than the tool holder 7 of the first embodiment. The tool holder 107 takes the form of a base block 108 to which an L-shaped support 109 is secured by a pair of fasteners 31. Slidingly positioned on the support 109 is a U-shaped carrier 110 which in turn supports a pair of bearers 111 between which an axle 112 extends and rotatably supports a pair of rollers 113 (which can be ball bearings if desired).

As best seen in Fig. 5, the blade 33 of the gouge 30 has a curvature to which the outer diameter of each roller 113 has been selected to substantially match. Thus a conventional chemical laboratory retort clamp 120, for example can be used to clamp the blade 33 against the axle 112 so that the gouge 30 is rotatably supported on the rollers 113. In addition, as best seen in Fig. 6, the base block 108 is able to be pivoted to the desired sharpening angle and the U-shaped carrier 110 slid in the direction of arrows C relative to the L-shaped support 109 so that the curved surface 126 is raised to a height equal to that of the upper surface of the roller 6.

In this position, the grindstone 20 is able to be reciprocated as indicated by arrow A and B in Figs. 5 and 6 so as to sharpen or hone just a single line element which forms the surface 126. This action is carried out by the right hand of the operator as best appreciated from Fig. 5. The operator is able to move his left hand in the arc indicated by arrows E in Fig. 5 so as to rotate the blade 33 of the gouge 30 about the axle 112 as indicated by the arrows D in Fig. 6. As a consequence, the line element of the surface 126 being sharpened is able to be progressed from left to right and back again across the surface 126 thereby sharpening the entire surface 126 which is convex and faces upwardly. As before, simply by raising the grindstone 20 the operator is able to observe the sharpening or honing procedure and gauge its effectiveness to date.

The above described arrangements provide a number of substantial advantages. As indicated above, since the surface or edge sharpened or honed is uppermost, it is easily inspected during the sharpening or honing process. In addition,

all angles are able to be adjusted and thus the individual preference of different users are able to be accommodated as contrasted with some prior art arrangements where only predetermined angles are able to be used.

The scale 12, which preferably extends for an entire quadrant, enables any desired sharpening or honing angle to be set directly. This enables small differences between the sharpening surface and the honing surface to be set, by as little as 0.5°, if desired. In addition, the scale makes the sharpening or honing activity reproducible since angles can be recorded and then reset at a later date as required.

hi addition, as mentioned above, implements with skewed cutting edges can also be sharpened. With the foregoing descriptions of the guide 1 in mind, some implements with skewed cutting edges can be sharpened using to tool holding arrangements illustrated in Fig. 9.

As best seen in Fig. 9, the guide 201 of the third embodiment is similar to the guide of the first embodiment. The guide 201 includes most features of guide 1 which are similarly numbered on Fig. 9. The major difference is that the guide 201 include a variation of a tool holder 207 which has an arcuate slot 217 located therein whereby a guide bar 218 associated therewith. The guide bar 218 has a pair of fasteners 220 and 221, the fastener 220 being received within a hole 222 in the holder 207 and the other fastener 221 being received within the arcuate slot 217. The guide bar 218 is therefore able to be pivoted about the fastener 220.

The guide 201 similar to the guide 1 includes a clamping piece 215 used to clamp the tool with the skewed cutting edge (not illustrated) against the tool holder 207, and aligned with the guide bar 218, which has been set up at the angle required.

The tool is thus able to be secured via the guide 201 such that the edge of the blade is set up perpendicularly to be able to be honed and sharpened as in the first embodiment.

A further advantage of the above described arrangements is that the components are able to be disassembled and reassembled for use by a left hander, not merely a right hander as illustrated. This requires two scales 12, one on each side of the wall 4 and mirror image reversal of the operating parts. This is a substantial advantage for many left handers who find tools designed for right handers difficult to operate. The ability to operate either in right hand mode, or in left hand mode, makes it easy to sharpen skew blades of opposite hands.

The foregoing describes only three embodiments of the present invention and modifications, obvious to those skilled in the tool sharpening arts, can be made thereto without departing from the scope of the present invention.

The term "comprising" (and its grammatical variations) as used herein is used in the inclusive sense of "including" or "having" and not in the exclusive sense of "consisting only of '.