Patent Publication Number: US-9833879-B1

Title: Hand-held sharpener with multi-stage sharpening capabilities

Description:
RELATED APPLICATIONS 
     The present application is a continuation of co-pending U.S. patent application Ser. No. 13/315,101 filed Dec. 8, 2011, which makes a claim of domestic priority to U.S. Provisional Patent Application No. 61/420,953 filed Dec. 8, 2010, the contents of which are hereby incorporated by reference. 
    
    
     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  113 A and bias spring  113 B. 
     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  120 A and a knife blade  120 B. A cutting edge along the lower distal extent of the blade  120 B is denoted at  120 C. 
       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  120 B 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  120 A with a second hand  144  (such as the right hand), and inserts the base of the knife blade  120 B into the channel  122  of the primary sharpening stage  114 . This will bring the base of the cutting edge  120 C 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  120 B. 
     Depending on the curvature of the blade  120 B, 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  120 A 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&#39;s body. 
     The user next places the base of the blade  120 B 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  120 B 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  120 B ( 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  814 A and  814 B, beveled side surfaces  816 A and  816 B, and opposing parallel side surfaces  818 A and  818 B. The beveled surfaces  816 A-B taper at a first sharpening angle θ 1 , and the beveled surfaces  814 A-B taper to a second, greater sharpening angle θ 2 . 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 θ 1  and 25 degrees for the second angle θ 2 , although other angles can be used. The shallower angle θ 1  enhances cutting strength and sharpness, and the deeper angle θ 2  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 θ 1 . 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 θ 1  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  816 A and  816 B 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 θ 2 . 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  814 A-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  814 A-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  816 A- 816 B 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.