Device for sharpening a cutting tool

Abstract

This disclosure relates to a device for sharpening an edge of a cutting tool. The device comprises a base; a clamping mechanism extending upwardly from to the base and comprising: a first clamp to clamp the cutting tool at a position proximal to a first end of the cutting tool, and a second clamp, inline with the first clamp and configured to clamp the cutting tool at a position distal to the first end of the cutting tool. A pair of arms extends upwardly, each arm of the pair of arms comprising a pivot to connect the arm to the base. A pair of abrasive elements are coupled to the arms to be in contact with the edge of the cutting tool, wherein the pivots provide for rotational movement that guides the pair of abrasive elements along the edge of the cutting tool.

Description

[0001] “Device for sharpening a cutting tool”

[0002] Cross-Reference to Related Applications

[0003] [1] The present application claims priority from Australian Provisional Patent Application No 2024903100 filed on 26 September 2024, the contents of which are incorporated herein by reference in their entirety.

[0004] Technical Field

[0005] [2] This disclosure relates to a device for sharpening the edge of a cutting tool, such as, but not limited to a knife.

[0006] Background

[0007] [3] Cutting tools, such as knives, often have a metal blade with a sharpened edge. The edge is sharpened by setting a precise angle, such as 20 degrees, on that edge. It is typically difficult to form such an angle when the blade is formed. Therefore, the setting of the angle is achieved by removing material from the edge to define that angle after forming the blade. This removal of material is performed by an abrasive surface, such as a sharpening stone or an abrasive diamond coated surface. This process involves a movement of the abrasive surface relative to the blade to remove the metal from the blade. However, it is a challenge to move the abrasive surface accurately while maintaining the desired angle.

[0008] Summary

[0009] [4] This disclosure provides a sharpening device that firmly grips the cutting tool in two vices and sharpens the cutting tool from both sides to set an accurate angle on the edge of the blade. The device provides minimal flex in the cutting tool while it is adjustable to different lengths of cutting tools.

[0010] [5] A device for sharpening an edge of a cutting tool comprises: a base; a clamping mechanism extending upwardly from to the base and comprising: a first clamp to clamp the cutting tool at a position proximal to a first end of the cutting tool, and a second clamp, inline with the first clamp and configured to clamp the cutting tool at a position distal to the first end of the cutting tool, the first clamp and the second clamp defining a longitudinal axis along respective clamping surfaces; a pair of arms, extending upwardly at either side of the clamping mechanism and at a distance from the longitudinal axis of the clamping mechanism, each arm of the pair of arms comprising a pivot to pivotably connect the arm to the base; a pair of abrasive elements coupled to the respective arms at a distance from the base to be in contact with the edge of the cutting tool, wherein the pivots provide for rotational movement that guides the pair of abrasive elements along the edge of the cutting tool along the longitudinal axis to sharpen the edge from either side of the edge.

[0011] [6] In some embodiments, the second clamp is moveable along the longitudinal axis to adjust for a length of the edge.

[0012] [7] In some embodiments, the second clamp is attached to the base by a slidable engagement with a track that extends along the longitudinal axis.

[0013] [8] In some embodiments, each of the pivots comprises a spring to provide the pivotable connection to the base.

[0014] [9] In some embodiments, the spring couples two segments of the arm and the two segments comprise rounded ends located inside the spring.

[0015]

[0010] In some embodiments, the base comprises multiple receptacles to receive the arm (post that is connected to the spring), the multiple receptacles being arranged with increasing distance from the longitudinal axis to adjust an angle between the abrasive element and the edge of the cutting tool to one of multiple pre-set angles.

[0016]

[0011] In some embodiments, the arm comprises a first segment coupled to the abrasive element and a second segment, coupled to the first segment by the pivot, the second segment being adapted to be removably received by the multiple receptacles.

[0012] In some embodiments, the multiple receptacles are arranged as an array with multiple rows and multiple columns wherein each column relates to a different length of the edge and each row relates to a different angle of the edge.

[0017]

[0013] In some embodiments, the base comprises a length indicator associated with each of the multiple rows.10. The device of any one of the preceding claims, wherein the abrasive element is slidably engaged with the arm to provide for movement along the arm.

[0018]

[0014] In some embodiments, the slidable engagement provides for rotation of the abrasive element about an axis defined by the arm.

[0019]

[0015] In some embodiments, the abrasive element is a multi-faceted block with abrasive material on each side of the multi-faceted block.

[0020]

[0016] In some embodiments, the abrasive material on each side of the multi-faceted block has a different grit.

[0021]

[0017] In some embodiments, the multi-faceted block is an elongated block with a square cross-section.

[0022]

[0018] In some embodiments, the block comprises central, longitudinal metal tube to provide slidable engagement with the arm.

[0023]

[0019] In some embodiments, each of the first clamp and the second clamp comprises a fixed jaw and a moveable jaw to clamp and release the cutting tool.

[0024]

[0020] In some embodiments, the moveable jaw is slidably moveable along a track transverse to the longitudinal axis.

[0025]

[0021] In some embodiments, the fixed j aw and the moveable j aw have a top angle that is greater than a sharpening angle defined by the receptable closest to the clamping mechanism.

[0026]

[0022] In some embodiments, the first clamp and the second clamp have a slot depth to receive the cutting tool entirely subject to the edge protruding above the first clamp and the second clamp.

[0023] In some embodiments, each of the clamps comprise a friction pad on an inside gripping surface to provide a high friction grip of the cutting tool.

[0027]

[0024] A method for sharpening an edge of a cutting tool comprises: securing the cutting tool in a clamping mechanism by: tightening a first clamp to clamp the cutting tool at a position proximal to a first end of the cutting tool, and tightening a second clamp, inline with the first clamp and configured to clamp the cutting tool at a position distal to the first end of the cutting tool; bringing a pair of abrasive elements, coupled to the pair of arms, into contact with the edge of the cutting tool, the arms extending upwardly at either side of the clamping mechanism and being pivotably connected to a base by a respective pivots; applying rotational movement to the arms about the pivots to guide the pair of abrasive elements along the edge of the cutting tool to sharpen the edge from either side of the edge.

[0028] Brief Description of Drawings

[0029]

[0025] Examples will now be described with reference to the following drawings:

[0030]

[0026] Figure 1 illustrates a device for sharpening an edge of a cutting tool.

[0031]

[0027] Figure 2 illustrates the track of Figure 1 in further detail in a perspective view.

[0032]

[0028] Figures 3a and 3b illustrate the fixed bracket from Figure 1 in perspective view and bottom view, respectfully.

[0033]

[0029] Figure 4a illustrates the second clamp from Figure 1.

[0034]

[0030] Figure 4b is a top view of the block from Figure 1.

[0035]

[0031] Figure 5 illustrates a fixed jaw of the clamps from Figure 1.

[0036]

[0032] Figure 6 illustrates a moveable jaw of the clamps from Figure 1.

[0033] Figure 7 illustrates two segments of the arms from Figure 1.

[0037]

[0034] Figure 8 illustrates the base from Figure 1 with an array of receptacles for receiving the arms.

[0038] Description of Embodiments

[0039]

[0035] Figure 1 illustrates a device 100 for sharpening an edge 101 of a cutting tool 102, such as a knife. Device 100 comprises a base 103 with a flat surface, which may serve as a platform to mount the elements described below. Base 103 may be made from a range of materials, such as wood, metal, plastic and others. Preferably, the base material is rigid to prevent flex or relative movement between the elements of device 100. Further, it is preferable to have a relatively heavy base 103 to reduce movement of the base on a working surface, such as a table top, during use. In the example of Figure 1, the base 103 is square but it may equally be rectangular, circular, ovoid, or of a different shape. It should further be noted that the base may be integrally formed with other elements of device 100.

[0040]

[0036] On the flat surface of base 100, there is a clamping mechanism 110 mounted to the base 103. Clamping mechanism 103 extends upwardly from to the base 103, which means in the direction of the surface normal of the flat surface of base 103. Clamping mechanism 110 is adapted to securely hold the blade of the cutting tool with minimal movement and minimal flex of the blade during use of the device 100. Clamping mechanism 110 comprises a first clamp 111 and a second clamp 112. First clamp 111 is adapted to clamp the cutting tool 102 at a position proximal to a first end of the cutting tool. Second clamp 112 is in line with the first clamp 111, which means that their clamping surfaces are parallel and colinear so that a straight cutting tool 101 can be clamped by both clamps 111 and 112 at the same time along the length of the blade of cutting tool 102 and with minimal flex in the blade of the cutting tool 102. Second clamp 112 is adapted to clamp the cutting tool 102 at a position distal to the first end of the cutting tool. In this example of sharpening a knife, the first end of the cutting tool is the end where the handle is attached to the knife and so the first clamp I l l is proximal to the handle and the second clamp 112 is distal to the handle.

[0041]

[0037] Since the first clamp 111 and the second clamp 112 are colinear, they define a longitudinal axis 113 along respective clamping surfaces. For example, the first clamp 111 and second clamp 112 may be formed by respective vices that each have two jaws to grip the cutting tool 102 therebetween. In that case, the longitudinal axis 113 is defined along the gripping surfaces of the jaws and in line with the edge 101 of cutting tool 102.

[0042]

[0038] Device 100 further comprises a pair of arms comprising a first arm 121 and a second arm 122. The arms 121 / 122 extend upwardly at either side of the clamping mechanism 110 and may be made of solid rods or hollow tubes. The arms 121 / 122 also extend from the base 103 at a distance from the longitudinal axis 113 of the clamping mechanism 110. So, first arm 121 extends upwardly on the left side of the clamping mechanism 110 while second arm 122 extends upwardly on the right side of the clamping mechanism 110. First arm 121 comprises a first pivot 123 at a set horizontal distance from the longitudinal axis 113 to pivotably connect the first arm 121 to the base 103. Similarly, second arm 122 comprises a second pivot 124 to connect the second arm 122 to the base 103 at the same set horizontal distance from the longitudinal axis 113 (although different distances could be set in some applications).

[0043]

[0039] Further, device 100 comprises a pair of abrasive elements comprising a first abrasive element 131 and a second abrasive element 132. The first abrasive element 131 and second abrasive element 132 are coupled to the respective arms 121, 122. The distance of the abrasive elements 131 / 132 from the base, along the arm, may be adjustable and may be chosen such that the abrasive elements 131 / 132 can be brought into contact with the edge 101 of the cutting tool 102. Then, the pivots 123 / 124 provide for rotational movement that guides the pair of abrasive elements 131 / 132 along the edge 101 of the cutting tool along the longitudinal axis 113 to sharpen the edge 101 from both sides of the edge 101. More specifically, an operator of device 100 slides the abrasive elements 131 / 132 up and down on the respective arms 121 / 122 so that they are at the right height to be in contact with edge 101. The operator then moves the abrasive elements 131 / 132 along the edge 101 while maintaining contact with the edge 101 in a back and forth motion or repeatedly in one direction only. The operator can apply pressure to the abrasive elements 131 / 132 to thereby provide pressure onto the edge 101 to enable the removal of material from edge 101 to set the desired angle on edge 101. The device 100 is designed such that this applied pressure does not significantly flex the cutting tool 102 to thereby set a constant angle. In addition to that back and forth movement, the operator can also move the abrasive elements 131 / 132 up and down along the arms to influence the removal of material from the edge 101 depending on the desired outcome. The operator may increase the safety of the sharpening process by using upwards strokes sliding the abrasive elements 131 / 132 along arms 121 / 122 upwardly and therefore away from the edge 101. This way the operator is less likely to cut their hand accidentally. This motion can be performed with relatively little sliding motion along the edge 101.

[0044]

[0040] The pivots 123 / 124 permit rotational movement which is constrained by the edge 101 when the abrasive elements 131 / 132 are in contact with the edge. As a result, there is only a single degree of freedom for the arms 121 / 122, which is a rotation in a plane that defines the angle of edge 101. There is a small variation of the angle on edge 101 along the length of the edge because the ends of edge 101 are further away from the pivots 123 / 124 than the middle of edge 101. This means that the movement of the arms is not perfectly circular with the pivot as the centre. However, this variation in angle is negligible for practical lengths of cutting tools and the angle can be considered constant along the edge 101.

[0045]

[0041] It is further noted that the pair of arms 121 / 122 provide a further advantage in the way the set-up reduces the time to sharpen edge 101. With single arm designs, the edge is sharpened on one side and then turned over the deburr the other side. Turning over the knife multiple times, takes considerable amount of time. With the design disclosed herein, both sides of the edge 101 are worked on at the same time, which means the cutting tool 102 does not need to be turned over, which significantly reduces the time required to sharpen edge 101.

[0046]

[0042] Returning to clamping mechanism 110, it is noted that second clamp 112 may be moveable along the longitudinal axis 113 to adjust for a length of the edge 101. This addresses the issue that longer knives tend to have more flex at the ends when using a single clamp. At the same time, shorter knives would not fit between clamps that are designed for long knives. Therefore, clamping mechanism 110 comprises a track 114 that extends longitudinally across base 103. Clamping mechanism 110 further comprises a movable bracket 115 that slidably engages with track 114 such as by a C shape that straddles the track 114 or a different engagement that allows longitudinal movement. Track 114 further comprises a channel 116 to receive a screw 117 that secures the second clamp 112 against movement in direction of the longitudinal axis 113 when the screw 117 is tightened. Transverse movement is restricted by the mating engagement between bracket 115 and track 114.

[0043] This provides for a rigid clamping of the cutting tool 102 in the device 100. Further, the adjustable second clamp 112 allows for adjustment for different knife lengths. It is noted that if both clamps 111 and 112 are placed close together relative to the length of the edge 101, there may be flex in the edge due to the pressure applied to the abrasive elements 131 / 132. At the same time, short edges and long edges need a different distance between the clamps 111 / 112. Therefore, the disclosed clamping mechanism 110 can securely clamp cutting tools of vastly different lengths securely with minimal flex to provide a constant cutting angle along edge 101. Similar to second clamp 112, first clamp 111 may be secured to track 114 by a fixed bracket 118.

[0047]

[0044] For knives that are relatively long with a relatively narrow blade, there can be a problem of flex since the blade is more flexible that other knives. To address this issue, the clamping mechanism 110 can be used to apply tension to the knife. This works by first inserting the knife into the fixed clamp 111 and tightening the fixed clamp. Then, while screw 117 is loose, sliding the moveable clamp 112 to the desired length of the knife. Then, while screw 117 is still loose, tighten the grip of the moveable vice 112. Now, the base of the moveable clamp 112 can be moved forward slightly at the base (at bracket 115), which results in a slight tilting of the movable clamp 112 since the knife holds the top of moveable clamp

[0048] 112 back. At this stage, screw 117 is tightened to secure the moveable clamp 112 in a tilted position on one side. A second screw, which is not shown in Figure 1 but in Figure 2, on the other side of the clamp 15 can now be tightened to pull down that side of the clamp. This pulls the top of the clamp 112 forward thus applying tension to the knife which further reduces flex. In yet a further use case, it is possible to sharpen blades that are significantly longer that the track 114, such as swords. This can be achieved by sharpening those blades in sections starting at one end of the blade, sharpening a first section and then moving the blade forward in the clamps 111 / 112.

[0049]

[0045] Figure 2 illustrates track 114 in further detail in a perspective view where the bottom side is shown. Channel 116 is visible while it is noted that channel 116 is wider or recessed at the bottom so that screw 117 can engage with a nut 203 that is inserted into the recessed part of the channel 116. When the screwl 17 is tightened, the top surface of the nut 203 abuts the bottom surface of the narrower part of the channel 116 to thereby secure the second clamp

[0050] 112. There may be a second screw in movable clamp 115 (not shown Figure 1 as it is covered by second clamp 112) and the nut 203 may be a single elongated flat piece of metal (as shown) with two threaded holes in it that spans the distance between both screws. This increases the contact area between the upper side of the nut and the underside of the channel 116 and therefore increases friction to secure the second clamp 112 more tightly.

[0051]

[0046] Track 114 further comprises four screw holes (one is indicated at 201) for fixing track 114 to base 103. Further, track 114 comprises three screw holes (one is indicated at 202) to secure the fixed bracket 118 to the track 114. Screw holes 202 may be countersunk so that the top of the screw heads are flush with the underside of track 114 so that the track can be mounted on the base 103 with direct contact across the entire underside of track 114.

[0052]

[0047] Figures 3a and 3b illustrate fixed bracket 118 in perspective view and bottom view, respectfully. Fixed bracket 118 comprises three threaded screw holes 301 at the bottom to engage screws that are fed upwardly through screw holes 202 of track 114 (see Figure 2). Tightening those screws secures the fixed bracket 118 to the track 114. Further, fixed bracket 118 comprises two jaw mounting holes 302 to secure a fixed jaw of the first clamp 111 to the bracket 118.

[0053]

[0048] Each of the first clamp 111 and the second clamp 112 comprise a fixed jaw and a moveable jaw to clamp and release the cutting tool 102. Figure 4a illustrates second clamp

[0054] 112, noting that first clamp 111 operates in a similar manner and is not separately described herein. Second clamp 112 comprises fixed jaw 401 (also shown in Figure 5) and the moveable jaw 402 (also shown in Figure 6). It is noted that clamp 112 is shown from the opposite view than shown in Figure 1. Moveable jaw 402 is slidably moveable along a channel 403 transverse to the longitudinal axis 113. Fixed jaw 401 has a first screw hole 404 to receive a first screw to close the clamp 112 by tightening the screw. That is, movable jaw 402 has a threaded hole 501 that corresponds (or is in line with) the first screw hole 404 to receive the first screw.

[0055]

[0049] Further, fixed jaw 401 has a second screw hole 405 that is threaded but there is no corresponding hole in movable jaw 402. As a result, tightening the screw inserted into second screw hole 405 will push the bottom end of moveable jaw 402. As a result, moveable jaw 402 pivots about the screw hole 501 acting as a fulcrum. As a result, the cutting tool 102 is gripped more firmly. The distance between the first screw hole 404 and the second screw hole 405 provides leverage that increases the gripping force and thereby increases the friction on the cutting tool 102 to hold it in place more firmly. Figure 5 also shows the threaded screw holes that correspond to holes 302 shown in Figures 3a and 3b. It is further noted that the bottom of moveable jaw 402 is chamfered 502 to allow for the pivoting or rotational movement caused by tightening the second screw in the second screw hole 405.

[0056]

[0050] It is noted that, as shown in Figure 1, the angle that is set on the blade is adjustable by changing the horizontal distance between longitudinal axis 113 and pivots 123 / 124. This can be achieved by moving the point where the arms 121 / 122 are attached to the base 103 closer or further away from the clamping mechanism 110. To this end, the base 103 comprises multiple receptacles, such as receptacle 141 that receives the arm 121. These receptacles 141 may be round threaded holes that correspond with a thread on the bottom of the arms, such as the pin 704 of the second segment 702 of the arm, which can be tightened by twisting a nut 705 (see Figure 7). , or of another shape, such as square, hexagonal, etc.

[0057]

[0051] At the closest point to the clamping mechanism, the sharpening angle of the edge 101 becomes very small, such 10 degrees or less, which may almost be impractical for a cutting tool, except in specialty applications, such as sharpening a cut throat. In addition, in order to use the closest receptacle, the clamps 111 / 112 would need to have a very small angle at the top (e.g. less than 10 degrees), which would reduce their rigidity. However, it has been found that the very small angle setting is useful for removing a burr from an already sharpened edge. This may be particularly useful when sharpening serrated knives that are sharpened only from one side. This would leave a burr on the other side, which can be conveniently removed from the other side with a very small angle. In that case, it is not necessary to move along the entire length of edge 101. Therefore, it is an advantage that the fixed jaw 401 and the moveable jaw 402 have a top outside angle 503 that is greater than the sharpening angle defined by the receptable closest to the clamping mechanism. Even though the abrasive elements 131 / 132 would be blocked by the jaws, it is possible to debur the part of the edge that is between the first clamp 111 and the second clamp 112, while maintaining a high rigidity in the clamps.

[0058]

[0052] It is noted that the clamps 111 / 112 define a slot for inserting the cutting tool 102 and the depth of that slot is defined by the distance between the top of the jaws 401 / 402 and the first screw hole 404 because the first screw inserted into the first screw hole 404 blocks further insertion of the cutting tool. Ideally, the first screw hole 404 would be higher to increase the leverage from the second screw. However, this would reduce the size of the cutting tool that can be inserted into the clamps 111 / 112. In some examples, the first clamp 111 and the second clamp 112 have a slot depth to receive the cutting tool entirely, subject to the edge protruding above the first clamp and the second clamp. That is, the abrasive elements 331 / 332 just clear the jaws 401 / 402 when they are moved along the edge 101. This prevents flex in the cutting tool and therefore provides for a more accurate edge angle.

[0059]

[0053] Further, each of the clamps 111 / 112 comprises a friction pad 504 / 505 on an inside gripping surface to provide a high friction grip of the cutting tool. The friction pads 504 / 505 may be made of a range of materials and preferably, made of a material that provides for high friction and also high compression strength because the compression created by the screw mechanism described above is considerable. In some examples, the friction pads 504 / 505 are made of material used in flexible fridge magnets, such as ferrite powder mixed with flexible binders such as rubber or plastic. This combination results in a pad that is both flexible and durable, providing excellent friction due to the rubber content, while the ferrite powder imparts magnetic properties. Additionally, neodymium magnets embedded in a flexible polymer matrix can also be used, offering superior magnetic strength along with high friction and compressive resistance. Another material is a composite of magnetic powders and thermoplastic elastomers, which can be engineered to balance flexibility, strength, and frictional properties, making them suitable for this application where maintaining a firm grip is desirable.

[0060]

[0054] Turning now to the pivots 123 / 124 in Figure 1, it is noted that each of the pivots 123 / 124 may comprise a spring to provide the pivotable connection to the base 103. In that sense, the spring couples two segments of the arm and the two segments comprise rounded ends located inside the spring. Figure 7 illustrates a first segment 701 and a second segment 702, while the spring between them is not shown for clarity but would be located at spring location 703 to connect the first segment 701 to the second segment 702. An advantage of the spring configuration is that the spring allows for temporary, mild increase of sharpening angle at the end of the upwards motion of the abrasive elements 131 / 132, which allows stropping or deburring the top of the blade. This is particularly useful when using the finest grit on the abrasive elements 131 / 132.

[0061]

[0055] The second segment 702 comprises a base pin 704 (which may be threaded) that is received by receptacle 141 (see Figure 1) and a nut 705 that also serves as a stop. The thread on pin 704 allows screwing the arm into the base. This way, the arm 121 is securely attached to base 103 but at the same time, can be removed easily to adjust the angle or to adjust for the length of the edge 101. Again, at location 703, both ends of the first segment 701 and the second segment 703 are rounded to provide unimpeded movement. There may also be a ball joint formed between the first segment and the second segment, such as by forming a concave surface in first segment 701 and a matching convex surface on second segment 702 or vice versa.

[0062]

[0056] As show in Figure 1 and in more detail in Figure 8, base 103 comprises multiple receptacles 801 to receive the arm, that is the pin 704 that is connected to the spring. The multiple receptacles 801 are arranged with increasing horizontal distance from the longitudinal axis 113 to adjust an angle between the abrasive elements 131 / 132 and the edge 101 of the cutting tool to one of multiple pre-set angles. The multiple receptacles 801 are arranged as an array with multiple columns 802 and multiple rows 803. Each column relates to a different length of the edge 101. Further, each row 803 relates to a different angle of the edge. Base 103 may further comprise a length indicator associated with each of the multiple rows. In some examples, the length indicator may be a number (e.g. in cm of the edge 101) or a colour coded indication. In Figure 8, there is a coloured dot 804 located under each column 802. The same colour is used at the edge of base 103 at a first end 805 and a second end 805 to represent a scale. The operator can now align the edge 101 with the scale and dependent on whether the edge 101 fits within the coloured indicators, can decide which column 802 to use for inserting the arms 121 / 122 to sharpen the current cutting tool. There may be another scale to indicate a knife that is too long and should be sharpened in multiple sections. For example, there may be a knife that still fits into the clamps 111 / 112 at their maximum length configuration. However, moving the abrasive elements 131 / 132 along the length of such a long edge 101, while moving upwardly along the length of the abrasive elements 131 / 132 results in hardly any upwards movement along the edge 101. In some cases, it is desired to have an angle of about 45 degrees (forward and upward) of movement across the edge.

[0063] Therefore, longer edges may be sharpened in sections to achieve such an angle.

[0064]

[0057] Returning to the abrasive elements 131 / 132, it is noted that they are slidably engaged with the arm to provide for movement along the respective arm 121 / 122. The slidable engagement provides for rotation of the abrasive element 131 / 132 about an axis defined by the arm 121 / 122. In some examples, the abrasive element 131 / 132 is a multi-faceted block with abrasive material on each side of the multi-faceted block and the abrasive material on each side of the multi-faceted block has a different grit. For example, each surface of the block may have a graduated grit so that the operator can rotate the block by one face to use a finer grit. In some examples, the multi-faceted block is an elongated block with a square cross-section and may comprise a central, longitudinal metal tube to provide slidable engagement with the arm. That is, the metal tube receives metal arm 121 / 122. The fit between the tube and the arm may be a loose fit to allow a sliding motion but sufficiently tight to prevent movement other than rotation and sliding along the arm. An advantage of having a metal tube, such as a brass tube, is that it is harder wearing compared to plastic. It is noted that the brass tube may be glued into the centre of the block.

[0065]

[0058] Further, the block may be a hollow box or tube with a square cross-section and open ends. Figure 4b is a top view of one block, showing the box 451. At the ends, respective plastic plugs with a central hole may provide support for the central brass tube. Each plastic plug may be formed out of four separate triangles. Figure 4b shows four triangles 452, 453, 454, 455 which comprise respective downward facing protrusions (not shown) that together match the inner shape of the box (rounded square). Therefore, they slot into the box 451 snugly. The triangles are slightly larger than the box to form a flange that sits on top of the box. Each triangle may have a different colour to indicate grit size on that side of the box. The plastic triangles may be produced by 3D printing. Each triangle has a circular cutout at the central comer to form a round opening 456 to receive the metal tube that receives the respective medal arms 121 and 122.

[0066]

[0059] It is noted that the clamping mechanism 110 including track 114, brackets 115 and 118, clamps 111 and 112 may be made of aluminium, such as by machining an aluminium block. This may involve the use of a computer numerical control (CNC) machine that automatically machines the aluminium block to produce a part that is provided to the machine by a three-dimensional digital model. The arms 121 / 122 may be made of steel. However, other materials, such as other metals or plastic may be used to make the clamping mechanism and the arms 121 / 122. The abrasive elements 131 / 132 may be made of plastic with diamond sheets glued thereon.

[0067]

[0060] It will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

1. A device for sharpening an edge of a cutting tool, the device comprising: a base; a clamping mechanism extending upwardly from to the base and comprising: a first clamp to clamp the cutting tool at a position proximal to a first end of the cutting tool, and a second clamp, inline with the first clamp and configured to clamp the cutting tool at a position distal to the first end of the cutting tool, the first clamp and the second clamp defining a longitudinal axis along respective clamping surfaces; a pair of arms, extending upwardly at either side of the clamping mechanism and at a distance from the longitudinal axis of the clamping mechanism, each arm of the pair of arms comprising a pivot to pivotably connect the arm to the base; a pair of abrasive elements coupled to the respective arms at a distance from the base to be in contact with the edge of the cutting tool, wherein the pivots provide for rotational movement that guides the pair of abrasive elements along the edge of the cutting tool along the longitudinal axis to sharpen the edge from either side of the edge.

2. The device of claim 1, wherein the second clamp is moveable along the longitudinal axis to adjust for a length of the edge.

3. The device of claim 2, wherein the second clamp is attached to the base by a slidable engagement with a track that extends along the longitudinal axis.

4. The device of any one of the preceding claims, wherein each of the pivots comprises a spring to provide the pivotable connection to the base.

5. The device of claim 4, wherein the spring couples two segments of the arm and the two segments comprise rounded ends located inside the spring.

6. The device of any one of the preceding claims, wherein the base comprises multiple receptacles to receive the arm, the multiple receptacles being arranged with increasingdistance from the longitudinal axis to adjust an angle between the abrasive element and the edge of the cutting tool to one of multiple pre-set angles.

7. The device of claim 6, wherein the arm comprises a first segment coupled to the abrasive element and a second segment, coupled to the first segment by the pivot, the second segment being adapted to be removably received by the multiple receptacles.

8. The device of claim 6 or 7, wherein the multiple receptacles are arranged as an array with multiple rows and multiple columns wherein each column relates to a different length of the edge and each row relates to a different angle of the edge.

9. The device of claim 8, wherein the base comprises a length indicator associated with each of the multiple rows.

10. The device of any one of the preceding claims, wherein the abrasive element is slidably engaged with the arm to provide for movement along the arm.

11. The device of claim 10, wherein the slidable engagement provides for rotation of the abrasive element about an axis defined by the arm.

12. The device of any one of the preceding claims, wherein the abrasive element is a multi-faceted block with abrasive material on each side of the multi-faceted block.

13. The device of claim 12, wherein the abrasive material on each side of the multifaceted block has a different grit.

14. The device of claim 12 or 13, wherein the multi-faceted block is an elongated block with a square cross-section.

15. The device of any one of claims 12 to 14, wherein the block comprises central, longitudinal metal tube to provide slidable engagement with the arm.

16. The device of any one of the preceding claims, wherein each of the first clamp and the second clamp comprises a fixed jaw and a moveable jaw to clamp and release the cutting tool.

17. The device of claim 16, wherein, the moveable jaw is slidably moveable along a track transverse to the longitudinal axis.

18. The device of claim 16 or 17, wherein the fixed jaw and the moveable jaw have a top angle that is greater than a sharpening angle defined by the receptable closest to the clamping mechanism.

19. The device of any one of the preceding claims, wherein the first clamp and the second clamp have a slot depth to receive the cutting tool entirely subject to the edge protruding above the first clamp and the second clamp.

20. The device of any one of the preceding claims, wherein each of the clamps comprise a friction pad on an inside gripping surface to provide a high friction grip of the cutting tool.

21. A method for sharpening an edge of a cutting tool, the method comprising: securing the cutting tool in a clamping mechanism by: tightening a first clamp to clamp the cutting tool at a position proximal to a first end of the cutting tool, and tightening a second clamp, inline with the first clamp and configured to clamp the cutting tool at a position distal to the first end of the cutting tool; bringing a pair of abrasive elements, coupled to the pair of arms, into contact with the edge of the cutting tool, the arms extending upwardly at either side of the clamping mechanism and being pivotably connected to a base by a respective pivots; applying rotational movement to the arms about the pivots to guide the pair of abrasive elements along the edge of the cutting tool to sharpen the edge from either side of the edge.

Images