Hand-held sharpener with multi-stage sharpening capabilities

Abstract

A multi-stage hand-held sharpener. In some embodiments, the sharpener has a handle adapted to be gripped by a hand of a user, the handle extending along a longitudinal axis between opposing first and second ends. A primary sharpening stage is provided in the handle between the first and second ends, the primary sharpening stage having a first abrasive surface extending at a first angle to facilitate a primary sharpening operation by a user upon the tool. An abrasive rod extends from the first end of the handle in a direction parallel to the longitudinal axis. The handle includes a substantially flat guide surface linearly extending from the first end toward the abrasive rod at a second angle, the abrasive rod and the guide surface forming a second sharpening stage adapted to facilitate a secondary sharpening operation by the user upon the tool.

Description

BACKGROUND

Cutting tools such as knives are used in a variety of applications to cut or otherwise remove material from a workpiece. A cutting tool often has one or more laterally extending, straight or curvilinear cutting edges along which pressure is applied to make a cut. The cutting edge is often defined along the intersection of opposing surfaces that intersect along a line that lies along the cutting edge.

Cutting tools can become dull over time after extended use, and thus it can be desirable to subject a dulled cutting tool to a sharpening operation to restore the cutting edge to a greater level of sharpness. A variety of sharpening systems adapted to carry out a sharpening operation are known in the art, including, but not limited to, grinding wheels, whet stones, abrasive cloths, abrasive belts and sharpening steels.

SUMMARY

Various embodiments of the present invention are generally directed to a multi-stage hand-held sharpener adapted to sharpen a cutting edge of a tool, such as a kitchen knife.

In some embodiments, a sharpener includes a handle having a longitudinal axis and an outer grip surface which surrounds said longitudinal axis, the outer grip surface adapted to be grasped by the hand of a user. A first sharpening stage is incorporated into the handle and includes a first abrasive surface. The first sharpening stage is adapted to facilitate a primary sharpening operation by a user upon the tool responsive to the user contactingly advancing the cutting edge of the tool against the first abrasive surface to define a first beveled portion of the first side surface that nominally extends at a first angle with respect to a centerline passing through a center of the blade portion and the cutting edge. A second sharpening stage is removably attachable to the handle. The second sharpening stage includes an elongated member which, when attached to the handle, extends from the handle in a direction parallel to the longitudinal axis, the second sharpening stage further having a substantially flat guide surface attached to the elongated member that linearly extends in a non-orthogonal direction with respect to a second abrasive surface on the elongated member at a second angle. The second sharpening stage is adapted to facilitate a secondary sharpening operation by the user upon the tool responsive to the user contactingly engaging the first side surface of the tool with the guide surface to orient the tool at said second angle, and advancing the cutting edge of the tool against the second abrasive surface while maintaining the tool at the second angle to define a second beveled portion of the first side surface between the first beveled portion and the cutting edge that nominally extends at the second angle with respect to the centerline.

In other embodiments, a knife sharpener is provided for sharpening a cutting tool having a blade portion with opposing first and second sides and a cutting edge therebetween. The sharpener has a handle adapted to be gripped by a hand of a user, the handle extending along a longitudinal axis between opposing first and second ends. A primary sharpening stage is provided in the handle between the first and second ends, the primary sharpening stage including a first abrasive surface extending at a first angle to facilitate a primary sharpening operation by a user upon the tool. An abrasive rod extends from the first end of the handle in a direction parallel to the longitudinal axis. The handle has a substantially flat guide surface linearly extending from the first end toward the abrasive rod at a second angle, the abrasive rod and the guide surface forming a second sharpening stage adapted to facilitate a secondary sharpening operation by the user upon the tool.

In further embodiments, a knife sharpener is provided for sharpening a cutting tool having a blade portion with opposing first and second sides and a cutting edge therebetween. The sharpener has a handle adapted to be gripped by a hand of a user, the handle extending along a longitudinal axis between opposing first and second ends. A motor is disposed within the handle. A first abrasive surface is disposed within the handle configured for rotation by the motor. A second abrasive surface extends from the first end of the handle in a direction substantially parallel to the longitudinal axis. A substantially flat guide surface linearly extends from the first end of the handle toward the abrasive rod at a selected angle.

These and other features and advantages that may characterize various embodiments can be understood with a review of the following detailed description section in conjunction with the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A provides a side elevational view of a two-stage hand-held sharpener in accordance with some embodiments.

FIG. 1B is a side elevational cross-sectional view of the sharpener of FIG. 1A in a retracted orientation.

FIG. 2A is an isometric depiction of the sharpener of FIGS. 1A-1B in conjunction with a cutting tool being presented against a first sharpening stage of the sharpener.

FIG. 2B is a close-up side elevational view of the first sharpening stage.

FIG. 2C is a close-up top plan view of the first sharpening stage.

FIG. 3A generally illustrates an exemplary primary (coarse) sharpening operation in accordance with various embodiments.

FIG. 3B generally illustrates an exemplary secondary (fine) sharpening operation in accordance with various embodiments.

FIG. 4 is an isometric representation of a two-stage hand-held sharpener in accordance with further embodiments.

FIG. 5A is a side elevational representation of the sharpener of FIG. 4.

FIG. 5B provides a cross-sectional elevational view corresponding to FIG. 4.

FIG. 6 presents an isometric representation of a two-stage hand-held sharpener in accordance with still further embodiments.

FIG. 7A is a side elevational view of the sharpener of FIG. 6.

FIG. 7B is a top elevational view of the sharpener of FIG. 6.

FIG. 8A depicts a cutting tool being presented for sharpening against an abrasive rod generally similar to the second stage abrasive rods of FIGS. 1-7.

FIG. 8B is a cross-sectional elevational view of a distal cutting edge of the cutting tool of FIG. 8A.

FIG. 8C depicts presentation of the cutting tool against a first-stage sharpener surface as depicted in FIGS. 1-7.

FIG. 8D depicts presentation of the cutting tool against a second-stage sharpener surface as depicted in FIGS. 1-7.

FIG. 9 shows alternative cross-sectional shapes for the elongated member of the embodiments of FIGS. 1-7.

DETAILED DESCRIPTION

Various embodiments are generally directed to a multi-stage hand-held sharpening system adapted to sharpen cutting tools, such as but not limited to kitchen knives and the like.

The sharpening system generally takes the overall form of a sharpening steel. As will be recognized by the art, a sharpening steel is a style of sharpener that facilitates a manual sharpening operation upon a cutting tool. Generally, a sharpening steel is a “dirk-like” member having an elongated abrasive member that extends from a user handle. The blade of the cutting tool, such as a knife, is sharpened by drawing the blade axially down along and laterally across the abrasive member. The term “steel” denotes the general style, rather than the material composition, of the sharpener.

As embodied herein, the sharpening system generally comprises a handle that incorporates a primary sharpening system, or stage, such as but not limited to a ripper, an electrically driven abrasive disc, a flat abrasive block, etc. The primary sharpening stage is adapted to provide a relatively coarse sharpening operation upon the tool.

A secondary sharpening stage of the sharpener provides a relatively fine sharpening operation upon the tool after use of the primary sharpening stage. The secondary sharpening stage includes an elongated abrasive member with an associated guide surface that establishes a presentation angle for the tool as the tool is advanced along the abrasive member.

For reference, the term “abrasive” will be understood broadly to describe a medium adapted to carry out one or more of the following sharpening operations upon a cutting tool to enhance its cutting effectiveness: smoothing, shaping, straightening, deforming, polishing, burnishing, filing, abrading or otherwise altering some physical characteristic of the tool, irrespective of whether or not material is removed from the cutting tool during the sharpening process.

The various exemplary abrasive rods disclosed herein can take any number of suitable forms, such as but not limited to steel, carbide, ceramic or diamond coated abrasive. The outer surface may be smooth or textured, and may be provided with regions with different types of surface features. A criss-crossing or otherwise ridged texture may be provided to the outer surface, or the surface may be smooth without any human observable gaps, ridges or undulations.

The abrasive media disclosed herein, which includes but is not limited to abrasive rods, may have any suitable shape including circular, rectangular, triangular, elliptical, segmented, disc-shaped, flat, etc. The abrasive media may be subjected to hardening, coating or other processing to enhance the sharpening characteristics. It is contemplated although not required that the abrasive media will have a hardness that is greater than a hardness of the cutting tool blade and that the abrasive media will exhibit little or no wear over time.

FIGS. 1A-2C show a hand-held sharpener 100 constructed and operated in accordance with some embodiments. The sharpener 100 includes a handle 102 with an outer surface 104 sized and shaped to be grasped by a hand of a user.

A pair of leg flanges 106, 108 extends from opposing proximal and distal ends of the handle 102. The leg flanges 106, 108 are dimensioned to contactingly engage a base surface (not separately shown) such as a countertop to allow the user to steady the sharpener 100 during use. The leg flanges 106, 108 may provide clearance for fingers of the user to wrap around an underside portion of the outer grip surface 104 of the handle 102. A through-hole aperture may be formed in the distal end leg flange 108 to facilitate hanging storage of the sharpener 100 when not in use.

An elongated member 110 extends from the handle 102 in a direction parallel to, and preferably centered about, a longitudinal axis 112 of the handle 102. The elongated member 110 is characterized as an abrasive rod, although such is not necessarily required as other forms of elongated abrasive members can be used. The axis 112 is shown to nominally pass orthogonally through the geometric center of the handle (and the rod), although it will be appreciated that this is merely illustrative and not limiting.

The abrasive rod 110 takes a generally cylindrical shape, although other elongated shapes can be used including tapered (frusto-conical) shapes. The rod 110 may be permanently affixed to the handle 102, or may be displaceable with respect to the handle.

In some embodiments, the rod 110 can be partially or fully retracted along the longitudinal axis 112 so as to be nestingly received within an interior passageway of the handle to shorten the overall length of the sharpener 100, as represented in FIGS. 1B and 2. This allows the rod 110 to be extended when needed (FIG. 1A). Suitable internal locking mechanisms can be used to facilitate sliding movement of the rod 110, such as end cap 113A and bias spring 113B.

In other embodiments, the rod 110 may be removable from the handle 102 to facilitate detachment and reattachment as required. It will be appreciated that the attached rod provides a general “steel type” configuration for the sharpener 100, and a detached rod provides a “two piece” configuration for the sharpener.

A first sharpening stage is denoted at 114 and is characterized as a “pull-through ripper” type sharpener. As best shown in FIGS. 2A-2C, the first sharpening stage 114 comprises first and second crossed, hardened metal sharpening blades 116, 118. The sharpening blades 116, 118 form a v-shaped gap through which a cutting tool, such as kitchen knife 120 in FIG. 2A, can be drawn during a primary sharpening operation. The exemplary kitchen knife 120 is shown to include a knife handle 120A and a knife blade 120B. A cutting edge along the lower distal extent of the blade 120B is denoted at 120C.

FIG. 2B shows a blade guide channel 122 formed in the handle 102 of the sharpener 100 by opposing sidewalls 124, 126 which extend into the handle 102 in a direction toward the longitudinal axis 112. The blade guide channel 122 forms an aperture through which the sharpening blades 116, 118 extend and provides guide surfaces to contactingly engage one or both sides of the knife blade 120B to maintain the knife 120 at a desired presentation angle as the knife is drawn against the sharpening blades 116, 118.

The sharpening blades 116, 118 can be made of a suitably hard material, such as but not limited to tungsten carbide or a so-called super-abrasive (e.g., diamond, CBN, tungsten carbide, etc.) coated steel. Non-metallic blades may also be used. The blades 116, 118 may be spring biased to receive and act upon the knife 120. Depending on the initial condition of the knife 120, the first sharpening stage 114 may be capable of removing relatively large amounts of material from the knife along the vicinity of the cutting edge to provide a primary, or coarse, sharpening operation upon the knife.

A second sharpening stage 128 includes the abrasive rod 110, which is used in some embodiments to provide a secondary, or fine, sharpening operation upon the knife after the primary sharpening operation of the first sharpening stage. One or more blade guides, such as opposing blade guides 130, 132, may be incorporated into the second sharpening stage 128. The blade guides 130, 132 extend at a selected angle with respect to the longitudinal axis to assist the user in establishing a suitable presentation angle for the knife 120 against the rod 110. The blade guides are relatively long and narrow to allow clearance for the sharpening of the base portion of a blade next to the handle. It is contemplated that the secondary sharpening stage will tend to remove less material than the first stage from the knife (if any material is removed at all during the secondary operation).

FIGS. 3A-3B generally illustrate an exemplary sharpening sequence using the sharpener 100. To sharpen the knife 120, a user grasps the handle 102 of the sharpener 100 with a firsthand 140 (such as the left hand) and lowers the handle 102 onto a countertop 142 or other suitable work surface so that the leg flanges 106, 108 contactingly engage the countertop 142. The user may apply a small downwardly directed bias force to maintain the leg flanges 106, 108 in stationary contact with the countertop. This orientation is depicted in FIG. 3A.

The user next grasps the knife handle 120A with a second hand 144 (such as the right hand), and inserts the base of the knife blade 120B into the channel 122 of the primary sharpening stage 114. This will bring the base of the cutting edge 120C of the knife 120 into the v-shaped gap defined by the blades 116, 118. The user thereafter draws the knife 120 back through the channel 122 along the length of the blade 120B.

Depending on the curvature of the blade 120B, the user may need to induce some forward canting of the knife blade as the knife is drawn back to ensure the entirety of the longitudinal extent of the blade passes through the v-shaped gap and contactingly engages the blades 116, 118. Depending on the state of dullness and/or the extent of damage existing in the knife, the knife may be drawn through the first sharpening stage a number of successive times, such as 3-5 times or more.

Once the primary sharpening operation is completed, the user, while retaining the handle 102 in the left hand 140 and the knife handle 120A in the right hand 144, removes the knife 120 from the channel 122, and raises the sharpener 100 from the base surface so that the abrasive rod 110 is pointing away from the user's body.

The user next places the base of the blade 120B against the abrasive rod 110 while contactingly engaging a side of the blade against a selected one of the blade guides 130, 132, as depicted in FIG. 3B. While maintaining the knife blade at this angular orientation, the user advances the blade 120B along the rod 110 while laterally drawing the blade across the rod. This sequence may be repeated a suitable number of successive times, such as 3-5 times or more.

The user then repeats these steps using the remaining one of the blade guides 130, 132 so that both sides are honed against the abrasive rod. The user may wish to rotate the knife 120 in the right hand 144 so as to access the remaining blade guide 130, 132.

It will be noted that the primary sharpening operation may not be required every time the knife 120 is sharpened; rather, once the knife has been sharpened using both primary and secondary stages, the knife may be returned to its former sharpness after use by simply employing the second stage.

FIGS. 4-5B generally illustrate another hand-held sharpener 200 constructed and operated in accordance with some embodiments. The sharpener 200 is generally similar to the sharpener 100 discussed above. One difference is that the sharpener 200 uses a motor-driven abrasive disc to provide primary sharpening operations upon a tool such as the knife 120.

The sharpener 200 includes a handle 202 with an outer grip surface 204 and opposing leg flanges 206, 208. As before, the leg flanges 206, 208 can provide clearance for the fingers of the user when the sharpener is placed on a base surface (denoted at 209 in FIG. 5A).

An elongated member 210 extends from the handle 202 parallel to a longitudinal axis 212 passing through the handle 202. As before, the elongated member 210 may be in the form of an abrasive rod, although such is not limiting. The rod 210 may be permanently affixed to the handle 202 or removable from the handle.

A first sharpening stage 214 is incorporated into the handle 202. As best shown in FIGS. 5A-5B, the first sharpening stage 214 includes an abrasive disc 216 which is rotated by an internal motor 218 via an interconnecting shaft 220. The motor 218 may be powered by an internal power supply 222 (e.g., battery pack), or may be powered by an external power source (e.g., transformed AC input voltage) through an electrical cord (not separately shown). Rechargeable batteries and a wireless recharging base station can be readily incorporated as desired. A user depressible, pressure sensitive switch 224 is mounted to the side of the handle 202. When depressed, the switch 224 initiates rotation of the disc 216.

Guide channels 226, 228 are formed by respective sidewalls 230, 232. The guide channels 226, 228 extend into the handle 202 to provide apertures that facilitate presentation of the knife blade 120B (FIG. 2) at suitable presentation angles against opposing sides of the rotating disc 216. The disc 216 is shown to have frusto-conical grinding surfaces, although other shapes and styles of discs can be used including flat discs, flexible discs, spring-loaded discs, etc.

A second sharpening stage 234 includes the abrasive rod 210 as well as a collar guide member 236. The collar guide member 236 supports a proximal end of the rod 210 and includes features that enable the member 236 to be removably affixed to the handle 202. The member 236 includes opposing blade guides 238, 240 to facilitate presentation of the tool against the rod 210 at a desired presentation angle.

As before, when the collar member 236 is affixed to the handle (e.g., FIG. 4), the sharpener 200 takes a general sharpening steel configuration. Two-stage sharpening can be carried out in a manner similar to that set forth above for the sharpener 100, using the motor driven disc 216 to effect the primary sharpening and the rod 210 and guides 238, 240 to effect secondary sharpening.

FIGS. 6-7 illustrate another hand-held sharpener 300 constructed and operated in accordance with some embodiments. The sharpener 300 is generally similar to the sharpeners 100, 200 except that the sharpener 300 employs a planar grinding surface in the handle to provide primary sharpening operations.

The sharpener 300 includes a handle 302 with an outer grip surface 304 adapted to be gripped by the hand of a user. The grip surface 304 includes a scalloped lower surface portion 306 to accommodate the fingers of the user and a thumb-stop upper surface portion 308 accommodates a thumb of the user. As desired, the scalloped projections along portion 306 can be extended to operate as base support surfaces as with the leg flanges discussed above. An abrasive rod 310 (or other elongated member) is arranged to extend from the handle 302 parallel to a longitudinal axis 312 of the handle 302 as before.

A first sharpening stage 314 comprises an abrasive block 316 affixed to a side of the handle 304. The abrasive block is shown to be substantially rectilinear in shape, although other suitable shapes can be used including shapes that follow the contour of the handle outline. The abrasive block is recessed into and extends through the handle 302 to provide a planar abrasive surface 318 for coarse sharpening operations.

A second sharpening stage 320 includes the abrasive rod 310 as well as opposing blade guide surfaces 322, 324 which are incorporated into the handle 302. As before, the blade guide surfaces 322, 324 are provide on opposing sides of the abrasive rod 310 adjacent a proximal end thereof to facilitate presentation of the tool against the abrasive rod 310 at a selected presentation angle.

It is contemplated that the rod 310 is retractable into an interior channel of the handle 302 as depicted in FIG. 7. In some embodiments, an elastomeric button 326 may be affixed to the proximal end of the rod 310. Engagement features incorporated into the handle (not separately shown) may cooperate with the elastomeric button 326 to allow a user to transition the rod between an extended position (FIG. 6) and a retracted position (FIG. 7). In this configuration, depression of the button 326 by the user serves to advance the rod 310 a short portion of the way toward the extended position, and the user can grasp the distal end of the rod and slide the rod to the fully extended position.

As before, two-stage sharpening can be carried out in a manner similar to that discussed above for the sharpener 100. Primary sharpening can be carried out by holding or fixturing the handle 302 against a base surface and manually presenting the cutting edge of the blade against the abrasive surface 318. Secondary sharpening can be carried out using the abrasive rod and guides as before. It will be noted that the abrasive block 316 can advantageously be used for blade reshaping efforts to repair a damaged blade. It will be further noted that abrasive blocks such as 316 can be readily incorporated into the sharpeners 100, 200 to provide additional sharpening capabilities.

As desired, a flip-top cover 328 can be incorporated into the handle 302, as generally depicted in FIG. 7B. The cover 328 can be used to cover the abrasive block 316 when not in use. The cover 328 can be hinged and configured to extend at a suitable guide angle to facilitate the imparting of a suitable presentation of the cutting tool against the abrasive surface 318 when the abrasive block 316 is in use. As desired, the block 316 may be affixed to the cover so that the block flips out and the body of the handle 302 may be used as a guide surface at the desired angle.

FIGS. 8A-8D illustrate various features associated with the foregoing embodiments. Another exemplary knife that can be readily sharpened by the sharpeners 100, 200, 300 is shown at 800 in FIG. 8A. The knife 800 includes a user handle 802 and a blade 804. The knife 800 can be sharpened by each of the various embodiments disclosed herein against an abrasive rod 806 by concurrently advancing the knife in an axial direction 808 while drawing the knife laterally across the rod 806 in a lateral direction 810. In this way, the entire length of the blade contactingly engages the rod. The user maintains the knife at the same reference orientation established by associated rod guide surface (not shown).

The blade 804 may be formed of any suitable material such as high carbon content stainless steel. While the knife 800 is a single bladed knife that tapers to a single cutting edge 812 (as shown in FIG. 8B), it will be noted that double bladed knives, as well as other types of cutting tools, can be readily sharpened by these systems by sharpening each cutting edge at a time.

The blade 804 in FIG. 8B is shown to have a micro-beveled configuration with respective beveled side surfaces 814A and 814B, beveled side surfaces 816A and 816B, and opposing parallel side surfaces 818A and 818B. The beveled surfaces 816A-B taper at a first sharpening angle θ₁, and the beveled surfaces 814A-B taper to a second, greater sharpening angle θ₂. These angles are relative to a centerline 819 that passes through the center of the blade 804 and through the cutting edge 812 as shown.

Suitable values for these sharpening angles of the knife 800 may be on the order of around 20 degrees for the first angle θ₁ and 25 degrees for the second angle θ₂, although other angles can be used. The shallower angle θ₁ enhances cutting strength and sharpness, and the deeper angle θ₂ improves durability of the cutting edge 812. The respective axial lengths of the angled surfaces can vary as required so that the various aspect ratios and dimensions are merely representative and not limiting.

FIG. 8C generally represents a first stage sharpening operation in accordance with the foregoing embodiments. In FIG. 8C, the knife 800 is presented by the user against an abrasive surface 820 to establish the first angle θ₁. It is contemplated that the first abrasive surface 820 may correspond to a selected one of the crossed blades 116,118 of the pull-through ripper of FIGS. 1-3, a selected side of the rotatable disc 216 of FIGS. 4-5, the abrasive block 316 of FIGS. 6-7, or some other abrasive surface (including but not limited to an abrasive rod).

Generally, the knife may be presented at the first angle θ₁ by a first guide surface 822 (denoted by dashed lines). This first guide surface may be provided, for example, by the sidewalls 124, 126 of the channel 122 and/or the respective blades 116, 118 in FIGS. 2A-2C, the opposing the sidewalls 230, 232 of the guide channels 226, 228 in FIG. 5A, the cover member 328 in FIG. 7B, or some other surface.

The contacting engagement of the knife against the first abrasive surface 820 will generally operate to remove relatively large amounts of material from the edge of the blade 804. Depending on the amount of material removed, the previously existing cutting edge and side surfaces may disappear and new ones formed. During this primary (coarse) sharpening, the beveled surfaces 816A and 816B will be formed and may extend to the end of the blade material and meet to form a first cutting edge 823.

FIG. 8D generally represents a second stage sharpening operation in accordance with the foregoing embodiments. In FIG. 8D, the blade 804 is subsequently presented by the user against a second abrasive surface 824 to establish the second angle θ₂. A suitable guide surface 826 can be used to set this angle. The second abrasive surface 824 in FIG. 8D can correspond to the outer abrasive surfaces of the abrasive rods 110, 210 and 310 in FIGS. 1-7, and the guide surface 826 can correspond to the respective abrasive rod guides 130, 132, 238, 240, 322 or 324. Other configurations can be used, however. For example, one or more reference guide surfaces can be disposed in other locations, such as but not limited to a position adjacent the distal end of the abrasive rod opposite the handle.

The second stage sharpening operation depicted in FIG. 8D generally operates to remove material from the distal end of the tip of the blade 804, thereby forming the side surfaces 814A-B and the cutting edge 812.

It will be appreciated that, given sufficient time and repetitive sharpening strokes, a dull blade could be honed to form the side surfaces 814A-B and cutting edge 812. However, it has been found that, in the case of a particularly dull, damaged or worn knife, that portion of the knife proximate the cutting edge may not contactingly touch the abrasive, so that the sharpening operation serves as a side-honing operation without affecting the characteristics of the cutting edge.

The various embodiments discussed above have used cylindrically shaped rods as the respective elongated members in the secondary sharpening stages. Other shapes and forms of elongated members can be used. For example, FIG. 9 shows a number of alternative cross-sectional shapes of elongated members that can be readily incorporated into the foregoing embodiments.

The views in FIG. 9 correspond to an end view (looking toward the distal end of the respective members). These alternatives include a square shaped member 902, a triangularly shaped member 904, a frusto-conical (tapered) member 906, a rectilinearly shaped member 908 and a curvilinearly shaped member 910. Other shapes and forms can be used, including hollow members. While it has been contemplated that the abrasive surface of the second sharpening stage will extend fully around the outer surface of the elongated member, such is not necessarily required. It will be appreciated that associated rod guide surfaces can be disposed at various angular orientations corresponding to the various surfaces in FIG. 9.

Accordingly, a multi-stage hand sharpener as disclosed herein can be beneficial in sharpening the blade of a cutting tool. It has been found that sharpeners configured as described herein can quickly and easily impart razor or “scary” sharpness levels to a wide variety of different types and constructions of knives.

At least some of the various embodiments disclosed herein allow the use of a replaceable and/or retractable rod (or other elongated member). This can provide a number of benefits, including the ability to use different forms, types and/or shapes of rods, including ceramic rods and diamond coated rods, tapered rods, rods of different lengths, rods with different grits, and so on. Also, as very hard ceramic can be brittle, the ability to retract or remove a ceramic rod can reduce the possibility of damage due to the sharpening system being inadvertently dropped or otherwise subjected to a shock event.

The ability to retract a rod also can be a space-saving feature, which can be useful in both a kitchen setting where space may be at a premium, as well as in a portable setting where the sharpening system is taken on a camping trip or other outing. While it is contemplated that rods are relatively hard and durable, it is contemplated that from time to time such rods may become damaged or worn, necessitating replacement which can be easily effected.

It will be noted that in at least some of the various exemplary embodiments discussed above the second sharpening angle imparted to the blade by the second sharpening stage (e.g., 128, 234, 320) will be nominally the same as the first sharpening angle imparted to the blade by the first sharpening stage (e.g., 114, 214, 314). For example, the pull-through ripper stage 114 of FIG. 1 can be configured to nominally remove material at a selected angle (e.g., 25 degrees) and the respective guides 130, 132 can also be set at this same selected angle (e.g., 25 degrees).

In such case, the knife or other tool is drawn through the ripper to nominally set the opposing sides of the cutting edge at the desired angle during the primary sharpening operation, and then the secondary sharpening operation along the abrasive rod performs fine honing of the cutting edge at this angle. This would generally result in a knife having the configuration in FIG. 8C with side surfaces 816A-816B tapering to cutting edge 823.

Alternatively, the primary and secondary stages can be configured to impart different sharpening angles to the knife 800 to provide micro-beveling (different angled tapers on the same side or opposing sides of the cutting edge). For example, the ripper stage 114 of FIG. 1 can be set to impart a relatively lower angle (e.g., 20 degrees) and the respective guides 130, 132 can be set at a relatively higher sharpening angle (e.g., 25 degrees), providing a micro-beveled blade as in FIGS. 8B, 8D.

Another benefit of the various embodiments disclosed herein is the ability to incorporate the guide surfaces adjacent the handle at the base (proximal end) of the rod (or other elongated member). This can enhance safety since the guides can serve as a hand guard, thereby protecting the hand of the user that grasps the handle. Moreover, the orientation of the sharpener is such that the blade of the tool is pointed and moved away from the hand and the body of the user during secondary sharpening against the rod.

While not limiting, it is contemplated that it may be beneficial to set the secondary guide angle to be equal to or greater than the primary guide angle associated with a previous sharpening operation to provide a so-called micro-bevel configuration to the finally sharpened tool, such as illustrated in FIG. 8B. This sequencing allows for some user error when honing on the sharpening rod with regard to presentation angle, force, contact uniformity, etc.

This sequencing also may facilitate an efficient subsequent re-sharpening with minimal (or no) material removal by use of the secondary abrasive. It will be appreciated that while such sequencing is preferred, such is not necessarily required. For example, it is readily contemplated that a sharpening sequence may take place at the greater angle followed by the lesser angle. This may operate to remove material and thin the blade, which may be desirable in some circumstances.

Various additional alternatives and configurations will readily occur to the skilled artisan upon a review of the present disclosure, and all such alternatives and configurations are encompassed by the present application. While the various embodiments disclosed herein have been generally directed to a sharpener suitable for sharpening a knife, it will be appreciated that other types of cutting tools can be readily sharpened as desired.

It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this detailed description is illustrative only, and changes may be made in detail, especially in matters of structure and arrangements of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims

1. A sharpener for sharpening a cutting tool having a blade portion with opposing first and second side surfaces and a cutting edge therebetween, the sharpener comprising: a handle having a longitudinal axis and an outer grip surface which surrounds said longitudinal axis, the outer grip surface adapted to be grasped by the hand of a user;a first sharpening stage incorporated into the handle and comprising a first abrasive surface and a first stage guide surface having a line contact portion that linearly extends at a first angle with respect to the first abrasive surface, the first sharpening stage adapted to facilitate a primary sharpening operation by a user upon the tool responsive to the user contactingly engaging the first side of the blade against the first stage guide surface and contactingly advancing the cutting edge of the blade portion against the first abrasive surface to define a first beveled portion on the second side surface; anda second sharpening stage comprising an elongated member which extends from the handle in a direction parallel to the longitudinal axis, the second sharpening stage further comprising a second stage guide surface having a line contact portion that linearly extends in a non-orthogonal direction with respect to a second abrasive surface on the elongated member at a single second angle, the second sharpening stage adapted to facilitate a secondary sharpening operation by the user upon the tool responsive to the user contactingly engaging the first side surface of the tool with the second stage guide surface to orient the tool at said second angle, and advancing the cutting edge of the tool against the second abrasive surface while maintaining the tool at the second angle to define a second beveled portion of the first side surface between the first beveled portion and the cutting edge.

2. The sharpener of claim 1, wherein the elongated member is characterized as an abrasive rod having a proximal end adapted for insertion into a corresponding recess in the handle to attach the second sharpening stage to the handle, and wherein the second stage guide surface is affixed to the elongated member adjacent the proximal end and extends toward an opposing distal end of the elongated member.

3. The sharpener of claim 2, wherein the abrasive rod is nominally cylindrically shaped.

4. The sharpener of claim 2, wherein the abrasive rod is nominally frusto-conically shaped.

5. The sharpener of claim 2, wherein the abrasive rod is nominally rectilinearly shaped.

6. The sharpener of claim 1, wherein the first sharpening stage comprises first and second crossed metal sharpening blades.

7. The sharpener of claim 1, wherein the second angle is greater than the first angle.

8. The sharpener of claim 1, wherein the second stage guide surface is a first guide surface on a first side of the elongated member, and the second sharpening stage further comprises a second guide surface attached to a second side of the elongated member and which has a line contact portion that linearly extends in a non-orthogonal direction with respect to the second abrasive surface on the elongated member at a single third angle.

9. The sharpener of claim 8, wherein the second and third angles are equal.

10. The sharpener of claim 8, wherein the second and third angles are not equal and both are greater than the first angle.

11. The sharpener of claim 1, wherein the first guide surface comprises a line contact that linearly extends toward the first abrasive surface so that the first angle extends from the first guide surface to the first abrasive surface.

12. The sharpener of claim 1, wherein the second angle is nominally 25 degrees or less.

13. A sharpener for sharpening a cutting tool having a blade portion with opposing first and second sides and a cutting edge therebetween, the sharpener comprising: a handle adapted to be gripped by a hand of a user, the handle extending along a longitudinal axis between opposing first and second ends;a primary sharpening stage in the handle between the first and second ends, the primary sharpening stage comprising a first abrasive surface extending at a first angle with respect to a first guide surface to facilitate a primary sharpening operation by a user upon the tool; andan abrasive rod extending from the first end of the handle in a direction parallel to the longitudinal axis, the handle comprising a second guide surface having a line contact portion that linearly extends from the first end toward the abrasive rod to provide a single second angle from the second guide surface to a second abrasive surface of the abrasive rod, the abrasive rod and the second guide surface forming a second sharpening stage adapted to facilitate a secondary sharpening operation by the user upon the tool.

14. The sharpener of claim 13, wherein the primary sharpening stage is characterized as a pull through ripper comprising a pair of crossed blade members.

15. The sharpener of claim 13, wherein the abrasive rod is substantially rectilinear in cross-sectional shape.

16. The sharpener of claim 13, wherein the handle further comprises a flat support surface configured to be contactingly placed on a base surface during a sharpening operation, and a recessed surface to provide clearance between the handle and the base surface.

17. The sharpener of claim 13, wherein the abrasive rod tapers at a distal end thereof opposite the handle.

18. The sharpener of claim 13, wherein the second guide surface is on a first side surface of the handle, and the handle further comprises a third guide surface on a second side surface of the handle, the third guide surface having a line contact portion that linearly extends from the first end toward the abrasive rod to provide a single third angle from the third guide surface to the abrasive rod.

19. The sharpener of claim 18, wherein the second and third angles are equal to or greater than the first angle.

20. The sharpener of claim 18, wherein the second and third second angles are not equal and both are greater than the first angle.

21. The sharpener of claim 13, wherein the handle further comprises an aperture extending through the second end of the handle.

22. The sharpener of claim 13, wherein the second angle is nominally 25 degrees or less.