Patent Abstract:
Apparatus and method for sharpening a tool, such as a chisel. A sharpening guide applies a clamping force to secure the tool and advances a beveled leading edge surface of the secured tool against an abrasive surface to sharpen a cutting edge while the guide is in an upright orientation. An alignment plate nestingly receives the guide in an inverted orientation to align the tool prior to sharpening. During alignment, a back surface of the tool slidingly contacts an upper plate surface and the cutting edge contactingly abuts an alignment feature which projects from the plate surface. In some embodiments, the alignment feature comprises a removable alignment pin selectively insertable into a plurality of spaced apart apertures, each providing a final bevel angle for the sharpened tool.

Full Description:
RELATED APPLICATIONS 
     This application makes a claim of domestic priority to U.S. Provisional Application No. 61/098,573 filed Sep. 19, 2008. 
    
    
     BACKGROUND 
     Cutting tools are used in a variety of applications to cut or otherwise remove material from a workpiece. A variety of cutting tools are well known in the art, including but not limited to knives, scissors, shears, blades, chisels, machetes, saws, drill bits, etc. 
     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 techniques are known in the art, including the use of grinding wheels, whet stones, abrasive cloths, etc. A limitation with these and other prior art sharpening techniques is the inability to precisely define the opposing surfaces at the desired angles to provide a precisely defined cutting edge. 
     SUMMARY 
     Various embodiments of the present invention are generally directed to an apparatus and method for sharpening a tool, such as a chisel. 
     In accordance with various embodiments, a sharpening guide has opposing first and second body portions which are configured to contactingly apply a clamping force to respective side surfaces of a tool to secure the tool to the guide. The guide is configured to present a beveled leading edge surface of the secured tool adjacent an abrasive surface to sharpen a cutting edge of the tool while the guide is in an upright orientation. The guide is further configured to present a back side of the secured tool against the abrasive surface to hone a portion of the back surface disposed between the first and second body portions while the guide is in an inverted orientation opposite the upright orientation. 
     In further embodiments, an alignment plate is configured to align the tool within the guide prior to application of said clamping force. The plate is configured to nestingly secure the guide to the plate while the guide is placed in the inverted orientation, and the tool is advanced through the inverted guide so that the back surface slides adjacent an upper plate surface and the cutting edge contactingly abuts an alignment feature which projects from the plate surface. The guide and the plate are further configured such that the clamping force is subsequently applied while said contacting abutment between the cutting edge and the alignment feature is maintained. 
     In further embodiments, the alignment plate comprises a plurality of spaced apart apertures which extend into the upper plate surface, wherein the alignment feature comprises an alignment pin with a body portion and a peg extension, the peg extension configured for insertion into each of the apertures in turn to establish different overall projection distances of the beveled leading edge surface from the guide to provide different final bevel angles for the sharpened tool. As desired, the body portion of the alignment pin comprises at least two opposing, outwardly facing contact surfaces each a different respective distance from a central axis of the peg extension to provide at least two different selectable bevel angles for the sharpened tool when the alignment pin is placed in each of the apertures in the alignment plate. 
     In still further embodiments, the first and second body portions each comprise a long side surface of a first length and a short side surface of a second length shorter than the first length. In this way, a selected tool can be alternately installed between the first and second body portions so that a cutting surface thereof extends from the guide adjacent the respective long side surfaces or the respective short side surfaces. 
     Various other features and advantages of the various embodiments of the present invention will be understood from a review of the following detailed description and associated drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevational depiction of a wideblade sharpening guide constructed in accordance with various embodiments of the present invention. 
         FIG. 2  illustrates various exemplary types of tools that can be sharpened using the guide of  FIG. 1 . 
         FIG. 3  is an isometric view of the guide of  FIG. 1  in conjunction with a selected tool from  FIG. 2 . 
         FIG. 4  is an end elevational view of the guide of  FIGS. 1 and 3 . 
         FIG. 5  generally illustrates an alignment assembly utilized in accordance with various embodiments to install a selected tool into the guide. 
         FIGS. 5A-5B  respectively show a preferred use of angle finder and perpendicularity features of the alignment assembly of  FIG. 5 . 
         FIG. 6  is a side elevational view of an alignment pin of the alignment assembly of  FIG. 5 . 
         FIG. 7  shows a corresponding top plan view of the alignment pin. 
         FIG. 8  is an isometric view of the guide and alignment assembly. 
         FIGS. 9 and 10  show top plan views of the guide and alignment assembly. 
         FIG. 11  shows a methodology for sharpening a leading edge of a selected tool on a stationary abrasive surface. 
         FIG. 12  shows an alternative methodology for sharpening a leading edge of a selected tool on a rotating abrasive surface. 
         FIG. 13  illustrates a methodology for honing a backplane of the tool on the stationary abrasive surface. 
         FIG. 14  illustrates an alternative methodology for honing the backplane of the tool on the rotating abrasive surface. 
         FIG. 15  shows a cross-sectional view of another tool with multiple beveled leading edge surfaces obtained using the guide and alignment assembly. 
         FIG. 16  sets forth an alternative embodiment for the alignment assembly. 
         FIGS. 16A and 16B  provide respective views of the alignment pin of  FIG. 16 . 
         FIGS. 17A and 17B  show respective isometric views of the alignment assembly of  FIG. 16  in conjunction with the guide and a selected tool. 
         FIG. 18  shows the guide in conjunction with another, relatively short tool 
         FIG. 19  shows an alignment of the tool and guide of  FIG. 18 , with the tool extending from a long side of the guide. 
         FIG. 20  shows a corresponding alignment of a relatively long tool in the guide, with the long tool extending from an opposing short side of the guide, and with the alignments of both  FIGS. 19 and 20  to the same bevel angle. 
         FIG. 21  sets forth a sharpening operation upon the aligned tool and guide of  FIG. 19 . 
         FIG. 22  sets forth a sharpening operation upon the aligned tool and guide of  FIG. 20 . 
         FIG. 23  shows a honing operation upon the aligned tool and guide of  FIG. 21 . 
         FIG. 24  shows a honing operation upon the aligned tool and guide of  FIG. 22 . 
         FIG. 25  is an exploded view of a quick-release attachment assembly of the guide. 
         FIG. 25A  is an elevational depiction of a release member of  FIG. 25 . 
         FIG. 26  is a side elevational view of the guide to further illustrate the quick-release attachment assembly. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is generally directed to improvements in the manner in which tools are sharpened, such as chisel-type tools having an elongated cutting edge. One problem associated with the prior art is the difficulty in presenting a tool at a desired geometry against an abrasive surface in an accurate and repeatable manner. 
     As discussed below, various embodiments of the present invention are generally directed to an apparatus and method for sharpening a tool. The various embodiments generally employ a sharpening guide which is used to advance the tool against an abrasive surface during a sharpening operation. The sharpening guide includes notches that facilitate honing of a back surface of the tool along an area disposed between respective body portions used to clamp respective sides of the tool. 
     In further embodiments, an alignment plate facilitates alignment of the tool within the guide prior to the sharpening operation. The guide and plate cooperate to provide accurate and repeatable sharpening geometries in a fast and easy to use manner. 
       FIG. 1  shows an exemplary wideblade sharpening guide  100 . The sharpening guide  100  facilitates the sharpening of a variety of cutting tools, including chisel-style tools such as shown at  102  and  104  in  FIG. 2 . The term “wideblade” generally denotes the ability to accommodate laterally extending tools of various widths, so that both extremely narrow and extremely wide tools can be respectively sharpened using the exemplary guide  100 . This is merely illustrative, however, and not limiting to the claimed subject matter. 
     The guide  100  is configured to support a selected tool, such as the tool  104 , at a selected angle and projection distance to enable sharpening of the tool against an abrasive surface  106 . The surface  106  can be stationary, in which case the guide  100  can be reciprocatingly advanced and retracted on the surface  106  via wheels  108 . Alternatively, the surface  106  can be moveable, such as in the case of a moving belt or rotating wheel (disc), in which case the guide  100  can be reciprocatingly advanced and retracted adjacent the moving surface. The orientation of the guide in  FIG. 1  will be referred to herein as an upright orientation. 
     The tool  102  in  FIG. 2  is characterized as a chisel with a user handle  110  and a blade portion  112 . The blade portion  112  includes opposing top and bottom surfaces, with the top surface denoted at  114  and the bottom surface (back surface) not visible in  FIG. 2 . The blade portion  112  has opposing edge surfaces, with one edge surface identified at  116  and the other edge surface not visible in  FIG. 2 . A beveled leading edge surface  118  extends from the respective top and edge surfaces to meet with the bottom surface along a cutting edge  120 . The leading edge surface  118  extends at a selected bevel angle, such as 25 degrees, although other bevel angles can be readily used. 
     The tool  104  is characterized as a plane (or plane iron) with a single piece, elongated construction. As with the chisel  102 , the plane  104  has opposing top and bottom (back) surfaces, edge surfaces and beveled leading edge surface. The top surface is denoted at  122 , one of the edge surfaces is denoted at  124 , and the beveled leading edge surface is denoted at  126 . The beveled surface  126  extends at an acute angle with the back surface (such as 25 degrees) to form a cutting edge  128 . 
       FIG. 3  shows the chisel  102  of  FIG. 2  installed onto the guide  100  of  FIG. 1 , and reveals the aforementioned bottom (back) surface  130  of the chisel  102 . The side of the chisel  102  opposite the side  116  is not visible in  FIG. 2 , but is denoted at  132 .  FIG. 4  shows a side elevational view of the sharpening guide  100  in a stand alone fashion without the cutting tools  102 ,  104 . 
     As set forth by  FIGS. 3 and 4 , the guide  100  includes opposing body portions  134 ,  136  which act as a vice to apply a clamping force to a selected tool on the respective edge surfaces such as  116 ,  132  of chisel  102 . A pair of rails  138 ,  140  facilitates sliding passage of the body portion  134  with respect to the body portion  136 . A worm gear is established by a threaded shaft  142  with user activated knob  144 . 
     The rails  138 ,  140  provide reference surfaces in that the back surface of the tool (e.g., surface  130 ) is maintained in contacting engagement with the rails  138 ,  140  when the tool is installed into the guide  100 . The guide  100  is configured to project the leading edge surface (e.g.  118 ,  126 ) of the tool at an appropriate angle for sharpening against the abrasive surface  106 . The tool further extends from the guide  100  a sufficient distance to facilitate a honing operation upon the bottom surface (e.g.,  130 ) against the abrasive surface when the guide  100  is inverted. 
       FIG. 5  shows an alignment assembly  150  used to install a selected tool onto the guide  100 . The alignment assembly  150  includes an alignment plate  152  and a removable alignment pin  154 . The plate  152  is preferably L-shaped as shown, although other configurations can readily be utilized as desired. 
     The alignment plate  152  nestingly secures the guide  100  while the guide is disposed in an inverted orientation. It will be appreciated that the inverted orientation is opposite the normal upright orientation used during sharpening of the leading beveled edge of the tool. 
     An array of slots  156  extends along one side of the plate  152  to serve as an angle finder to identify an existing angle of a given tool. For example,  FIG. 5A  shows insertion of the beveled leading edge  120  of the tool  102  into the slot  156  corresponding to an angle of 25 degrees, thereby identifying the angle of the beveled leading edge  118  as nominally corresponding to this value. Human readable indicia (15, 20, 25, etc.) are provided adjacent the corresponding slots  156  to identify the corresponding angular values. The indicia can be printed, molded, stamped, etc. as desired. 
     The angle finder capability provided by the slots  156  can be helpful when the particular angle of a given tool is initially unknown, and the user desires to maintain the tool with this same nominal angle. It will be appreciated, however, that the guide  100  can be used to provide a different final angle for the leading edge of the tool; for example, the user may desire to reshape a tool with an initial angle (e.g., 25 degrees, etc.) to a different final angle (e.g., 30 degrees, etc.). In such cases, the angle finder capability need not be utilized. 
     Continuing with  FIG. 5 , the plate  152  further includes a base portion  158  configured to matingly receive the inverted guide  100 , and an extension portion  160  configured to set an outermost distal extent of the tool during alignment. The base portion includes a base surface  162  and opposing, laterally extending lip flanges  164 ,  166  which nestingly receive the body portions  134 ,  136  of the guide  100 , as shown below. 
     The flange  164  further provides a reference surface  168  which can be utilized as shown in  FIG. 5B  to evaluate perpendicularity of the cutting edge  120  of the tool  102  prior to installation. A pair of elongated mounting apertures  170 ,  172  extends through the base portion  158  to facilitate hanging storage of the plate  152  when not in use, and/or to facilitate the mounting of the plate  152  to a suitable horizontal work surface during use. 
     The alignment pin  154  is shown in  FIG. 6  to include a substantially triangular body portion  174  and a cylindrical shaft, or peg  176 . The peg  176  is sized to be selectively placed in a number of different annular apertures  178  in the extension portion  160  of the plate  152  (see  FIG. 5 ). As with the angle finder slots  156 , human readable indicia (15°, 20°, 25°, etc.) are provisioned adjacent the respective apertures  178 . It will be appreciated that the apertures  178  for smaller bevel angles are located increasingly farther away from the base portion  158 , whereas the apertures  178  for larger bevel angles are located increasingly closer to the base portion  158 . 
       FIG. 7  shows a top plan view of the alignment pin  154 . In some embodiments, the alignment pin has three opposing abutment surfaces  180 ,  182  and  184 , marked with corresponding indicia of 0, +1 and −0.5. The relative shapes and/or placement of the peg  176  therewith are selected such that controlled deviations from a base bevel angle can be achieved. More specifically, when the alignment pin  154  is placed into a corresponding aperture  178  in the extension portion  160 , the user has the option of placing any one of the three abutment surfaces  180  (0),  182  (+1) or  184  (−0.5) in facing relation to the base portion  158  so that the tool abuts that selected surface. 
     For example, when the alignment pin  154  is placed in the 25° aperture so that the surface  180  is in the aforedescribed facing relation, the tool will be set to provide a finished bevel angle of nominally 25°. Use of the surface  182  will nominally provide a finished bevel angle of 25+1=26°, whereas use of the surface  184  will nominally provide a finished bevel angle of 25−0.5=24.5°. Such adjustability can be advantageous in certain situations, such as to compensate for angular drift over a succession of sharpening operations on a given tool. 
       FIG. 8  shows a preferred manner in which a selected tool, in this case the chisel  102 , is installed onto the guide  100  using the alignment assembly  150 . The alignment pin  154  shown to be installed in the aperture  178  of the plate  152  corresponding to a bevel angle of 25°. 
     Initially, the user loosens the user activated knob  144  to separate the respective body portions  134 ,  136  of the guide  100  to permit sliding passage of the blade portion  112  of the tool  102  therebetween. The user next places both the guide  100  and the tool  102  onto the plate  152  so that the body portions  134 ,  136  nest onto the base portion  158  of the plate, and the tool  102  rests upon the respective rails  138 ,  140 . The user next advances the tool through the guide  100  and along the rails  138 ,  140  until the beveled leading edge  118  comes into contacting abutment against the alignment pin  154 . 
     At this point, while maintaining contact of the tool against both rails  138 ,  140  and against the alignment pin  154 , the user tightens the knob  144  so as to establish a clamping force upon the tool  102  and maintain the tool in this position via the respective body portions  134 ,  136 . Respective top plan views of this operation are generally shown in  FIGS. 9 and 10 . In  FIG. 9 , the alignment pin  154  is set so as to provide abutment against the 0 degree surface  180 , whereas in  FIG. 10  the alignment pin  154  is set so as to provide abutment against the +1 degree surface  182 . It will be noted that the alignment pin  154  may rotate so as to ensure parallel alignment of the facing surface with the presented beveled leading edge. 
     Once the tool has been installed onto the sharpening guide  100 , the guide and tool are removed from the alignment plate  152 , and the beveled leading edge  118  is thereafter presented against a suitable abrasive surface for sharpening thereagainst.  FIG. 11  shows installation of the cutting tool  104  onto the sharpening guide  100  and reciprocal movement of the sharpening guide  100  and cutting tool  104  along a stationary abrasive surface  190 , such as a layer of sandpaper or similar media adhered to a glass block  192  or other suitable substrate. As noted previously, controlled forward and backward motion can be achieved by the user grasping the tool and/or the guide  100  and advancing and retracting the tool and guide. A three-point contact is established by the respective wheels  108  and the beveled leading edge of the tool. 
       FIG. 12  shows the use of a sharpening assembly  200  in conjunction with the guide  100 . The sharpening assembly  200  utilizes a motor (not shown) within a housing  202  to controllably rotate an abrasive disc  204  at a selected rotational rate. A table structure  206  is preferably provided adjacent the disc  204  to provide a surface along which the guide  100  can be rolled to advance and retract the tool  104  against the disc  204 . Preferably, the table surface is nominally at the same elevational height as the disc  204  in order to maintain the desired geometries during the sharpening operation. Any number of other moveable or stationary abrasive surfaces can be provisioned for use with the guide  100 . 
     As those skilled in the art will appreciate, the sharpening of the beveled leading edge in a manner such as illustrated in  FIGS. 11-12  can result in accumulation of removed material (e.g., a burr) that extends from the cutting edge. Accordingly, in a preferred sharpening sequence, the beveled leading edge and the back surface are alternately presented for sharpening against the associated abrasive surface while maintaining the guide in the inverted orientation. 
     With respect to the use of the stationary abrasive layer  190  in  FIG. 11 , after a relatively small number of forward and backward cycles (e.g., 5-6), the guide  100  and associated tool are inverted as shown in  FIG. 13  so that the bottom surface of the tool can be brought into flat contact with the abrasive layer  190 . As before, light pressure is applied by the user while moving the guide and the tool forward and backward (or side to side) as shown to hone the back surface and remove such burred material from the cutting edge. 
     The skilled artisan will appreciate that it may not be necessarily required to advance and retract the guide and tool when a moveable abrasive is utilized such as with the sharpening assembly  200  of  FIG. 14 , since a sharpening operation will take place as a result of the abrasive medium moving adjacent the stationary tool. Nevertheless, forward and backward movement of the guide and tool in  FIG. 14  is preferably employed to further ensure uniformity of the sharpening process. 
     As before, after a relatively short period of grinding with the tool  104  and guide  100  oriented as shown in  FIG. 12 , the guide is inverted as shown in  FIG. 14  to present the bottom surface against the abrasive disc  204  to carry out a corresponding honing operation thereon. It is contemplated that a relatively small number of sharpening/honing cycles, such as on the order of 3-5 or more, may be sufficient to achieve the requisite sharpness for a given tool. A variety of factors, including the material composition and condition of the tool, as well as any desired changes in tool geometry (such as the implementation of a different bevel angle), may require the use of a significantly greater number of additional cycles. 
     Different levels of abrasiveness of the various abrasive layers may further be desired; for example, a relatively coarse grit (e.g.,  120  grit, etc.) may be initially used to remove relatively large amounts of material from the tool, followed by one or more finer grits (e.g., 400, 1200, etc.) to successively provide finer sharpening of the respective surfaces. 
     It may be desirable to provide a tool with multiple beveled lead edge surfaces at different angles, such as exemplified by another tool  210  in  FIG. 15 . The tool  210  is shown in cross-section for clarity of illustration, and may correspond to a chisel such as  102 , a plane such as  104 , or some other style of cutting tool. The tool  210  includes opposing top and bottom surfaces  212 ,  214 , and first and second beveled leading edge surfaces  216 ,  218 . The first leading edge surface  216  extends at a first angle, such as about 25°. The second leading edge surface  218  has a greater second angle, such as about 45°, and meets the bottom surface  214  to form a cutting edge  220 . The use of the second leading edge surface  218  generally provides a stronger cutting edge  220  as compared to a cutting edge  222  (shown in broken line fashion) formed using a lower angle, and therefore may provide different cutting characteristics and greater wear resistance. 
     The tool  210  can be provisioned with the characteristics shown in  FIG. 15  by providing a first sharpening sequence whereby the tool  210  is aligned in the alignment assembly  150  to provide a bevel angle of 25°, followed by sharpening/honing operations such as shown by  FIGS. 11 and 13  or  FIGS. 12 and 14 . This forms the first leading edge surface  216  and the first cutting edge surface  222 . 
     The tool  210  is then be reinserted into the guide  100  and realigned with the alignment assembly  150  for the second bevel angle of 45°, after which the sharpening/honing operations are repeated with this new setting. This results in the removal of the material bounded by the broken lines in  FIG. 15  and formation of the second beveled leading edge surface  218  and final cutting edge surface  220 . It will be appreciated that multiple abrasive levels can be utilized during either or both of these respective sharpening sequences. In a preferred embodiment, a relatively coarse grit is used for the first sequence, followed by the use of a relatively fine grit for the second sequence. 
       FIG. 16  shows an alternative alignment assembly  230  generally similar to the alignment assembly  150  set forth above. The alignment assembly  230  includes an L-shaped alignment plate  232 , and a rectangular alignment pin  234  ( FIG. 16A ). As before, the plate  232  includes a number of slots  236  that serve as an angle finder, a base portion  238  to nestingly receive the guide  100  (see  FIGS. 17A-B ) and an extension portion  240  with a plurality of alignment apertures  242  to receive the alignment pin  234 . 
     As shown in  FIG. 16A , in some embodiments the alignment pin  234  only utilizes a single abutment surface  244  against which an associated tool is brought into contact, such as shown for the tool  104  in  FIGS. 17A-B . In other embodiments, however, the alignment pin  234  can utilize a peg  246  that is offset with respect to a body portion  248  thereof, as generally represented in  FIG. 16B , in which case incremental positive or negative adjustments to the bevel angle can be provided as set forth above. 
     Reference is now made to  FIGS. 18-24 , which generally illustrate the ability of the guide  100  to accommodate a wide variety of tool lengths. In this context, “tool length” generally refers to a dimension of the tool normal to the cutting edge (for example, with respect to the chisel  102  in  FIG. 2 , the distance from the cutting edge  120  to the distal end of the handle  110 ). 
       FIG. 18  shows the guide  100  with a relatively short bladed tool  250  installed therein so as to be clamped between the respective body portions  134 ,  136 . It is noted that the respective body portions  134 ,  136  are substantially triangular in shape, each with a so-called long surface  134 A,  136 A and a so-called short surface  134 B,  136 B. 
     For reference, the side of the guide  100  adjacent the long surfaces  134 A,  136 A is generally referred to herein as the “long side,” and the other side of the guide  100  adjacent the short surfaces  134 B,  136 B is generally referred to herein as the “short side.” It will be noted that the short bladed tool  250  is installed in  FIG. 18  so as to extend from the long side of the guide  100 , although such is not limiting. 
       FIG. 19  shows a side elevational view of the guide/tool arrangement of  FIG. 18  in conjunction with the alignment plate  230  of  FIG. 16 . A cutting edge  252  of the tool  250  is brought into contacting abutment with the alignment pin  234  of  FIG. 17  to align the tool  250  for a selected angle (in this case, a bevel angle of 30 degrees). 
     It will be noted that the respective profiles of the body portions  134 ,  136  are substantially identical and take what can be referred to as an asymmetric arrow-head configuration. The respective angled surfaces  136 A,  136 B are substantially normal one to the other (i.e., about 90 degrees apart), although other configurations can be used in other embodiments. 
     A base surface is denoted at  136 C, and long and short side shoulders, or notches, are formed by respective shoulder surfaces  136 D/ 136 E and  136 F/ 136 G. For reference, similarly identified features are denoted on the other body portion  134  in other figures in which the other body portion  134  is visible, such as in  FIG. 20 . As explained below, the notches are nominally symmetric and provide clearance during back side honing operations. 
       FIG. 20  shows the guide  100  with a relatively long tool  260  installed therein so as to project from the short side of the guide  100 . As in  FIG. 19 , the guide  100  and tool  260  are mated with the alignment plate  230  of  FIG. 16 , so that a distal cutting edge  262  of the long tool  260  contactingly engages the alignment pin  234 . As in  FIG. 19 , the tool  260  in  FIG. 20  is also set to establish a selected bevel angle of 30 degrees. 
     At this point, reference is again made to the alignment plates  150 ,  230  of  FIGS. 5 and 16 . It can be seen that each plate includes two separate sets of pin apertures ( 178  and  242 ), with a first set of apertures arranged along the left side of the associated plate  150 ,  230  and a second set of apertures arranged along the right side of the associated plate. The left-side apertures are utilized to set the bevel angle when the tool extends from the long side of the guide  100  (see e.g.,  FIG. 19 ), and the right-side apertures are utilized to set the bevel angle when the tool extends from the short side of the guide  100  (see e.g.,  FIG. 20 ). 
     This provides a number of benefits, including the ability to have sufficient distance to clamp and align a relatively short tool, such as the tool  250 . It will be noted, for example, that there may not be sufficient tool length distance to clamp and align the short tool  250  to a bevel angle of 30 degrees if the short tool  250  is made to extend from the short side of the guide  100 . Generally, the guide  100  as embodied herein can accommodate substantially short tool lengths, such as down to about 1½ inches. There is generally no upper maximum limit on tool length. 
       FIGS. 21-22  respectively show preferred sharpening operations on the tools  250 ,  260  on an associated abrasive surface  264 . The wheels  108  allow the aforementioned reciprocal movement of the guide  100  with respect to the abrasive surface  264 , and the angular orientation of the guide  100  with respect to the abrasive surface  264  will be maintained to present the tool at the desired bevel angle. 
       FIGS. 23-24  respectively show corresponding back-side honing operations on the tools  250 ,  260 . The notches in the respective body portions  134 ,  136  provide clearance to facilitate maximum exposure of the associated back-sides of the tools  250 ,  260  to the abrasive surface  264 . Specifically, the relative elevation of the shoulder surfaces  134 D/ 134 F and  136 D/ 136 F are set so as to not mechanically interfere (contact) the abrasive surface. This is achieved by setting the elevations of the shoulder surfaces to be “lower” than the elevational height of the reference surfaces provided by the rails when the guide is inverted. 
     The back side of a given tool can thus be honed all the way back to the respective surfaces  134 E/ 134 G and  136 E/ 136 G; that is, that portion of the backside between the respective body portions (forward extending ends adjacent  134 D/ 134 F and  136 D/ 136 F) can be honed because the forward extending ends will not mechanically interfere with the abrasive surface. This can be particularly important during the sharpening of short tools with very little stickout from the end of the guide. 
       FIG. 25  provides an exploded view of the guide  100  to illustrate preferred quick-release clamping features of the guide. It will be recalled that the body portion  134  is advanced or retracted with respect to the body portion  136  via a worm gear arrangement established by the threaded shaft  142  and user activated knob  144 . While this arrangement can be fixed, such as in a conventional vise so that the body portion  134  remains permanently engaged with the threads of shaft  142 , in preferred embodiments a spring biased release assembly  270  is used to allow the body  134  to be quickly and easily advanced along the shaft  142 . This can be useful, for example, when a relatively wide (or narrow) tool is presented for sharpening via the guide  100 , and the user desires to quickly open (or close) the width of the body portions  134 ,  136  to conform to the width of the tool. 
     The release assembly  270  generally includes a locking member, such as a spring nut  272 , to capture a base of the shaft  142  adjacent the knob  144  to the body portion  136 . The shaft  142  is inserted through an unthreaded aperture  274  in the body portion  136 , and the spring nut  272  engages the shaft  142  on a side of the body portion  136  opposite the knob  144  to retain the knob  144  adjacent the body portion  136 . 
     A deflectable release member  276  is retained in a channel  278  of the body portion  134 , and an upwardly directed bias force (as oriented in  FIG. 25 ) is placed upon the release member  276  by a biasing member  280  (in this case, a coiled spring). The release member  276  includes an elongated, half-nut aperture  282 , as generally denoted in  FIG. 25A , with a threaded portion  284  along a bottom surface of the aperture  282 . An upper portion of the aperture  282  remains unthreaded and sized to allow the shaft  242  to pass freely therethrough. 
     The bias force provided by the biasing member  280  normally retains engagement of the threads of the shaft  242  with the threads  284  in the aperture  282 . In this way, during normal operation, rotation of the shaft  242  via knob  244  induces the aforedescribed worm gear linear advancement of the body portion  134  with respect to the body portion  136 . However, when the user presses downwardly upon the release member  276  via press surface  286  ( FIG. 25 ), the threads  284  are disengaged from threads of shaft  242 , and the body portion  134  can be freely advanced along the length of the shaft  242 . 
     Preferably, the release member  276  and channel  278  are canted with respect to the threads of the shaft  142  so that the release member  276  does not disengage when a clamping force is placed onto a tool. That is, any attempt by the release member  276  to disengage from the shaft  142  during tightening upon a tool will induce inward movement of the body portion  134  toward the body portion  136 , and the clamped tool will prevent such inward movement as a result of mechanical interference. Hence, once a tool has been tightly clamped between the body portions  134 ,  136 , it may be necessary for the user to first release the clamped pressure by rotating the knob  144  and advancing the body portion  134  away from the tool a slight distance before the release member  276  can be depressed. 
     It will be appreciated that the various embodiments set forth herein provide advantages over the prior art. The guide as exemplified at  100  provides an easy to use, accurate and repeatable mounting mechanism for any number of tools, particularly those characterized as having relatively wide blade widths. The alignment assembly such as exemplified at  150  and  230  enables a given tool to be accurately placed within the guide for any number of different sharpening geometries. 
     Any number of different styles of abrasive surfaces, including stationary blocks, grinding/whet stones, grinding wheels, abrasive discs, belts, abrasive sandpaper affixed to a flat glass block, etc. can be utilized with the sharpening guide, alone or in combination, to effect extremely sharp cutting surfaces, approaching or exceeding razor sharpness. Multiple and/or successively finer grits of abrasiveness can further be utilized as desired, depending on the requirements of a given application. 
     Moreover, while side-clamping is preferably used to clamp the tool within the guide, it will be appreciated that other clamping orientations, such as clamping of the top and bottom surfaces of the tool, can be alternatively or additionally provided. 
     For purposes of the appended claims, the term “acute angle” and the like will be understood consistent with the foregoing description as an angle of less than 90 degrees. The term “honing” and the like requires concurrent contact by the abrasive surface along the entire width of the back side of the tool (from side to side) as opposed to just a portion of the width of the back side to ensure flatness of this back side. 
     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.

Technology Classification (CPC): 1