Abstract:
Apparatus, systems and methods in accordance with the present invention are related to sharpening blades for rotary cutters. In one illustrative embodiment of a system in accordance with the present invention, an elongated sharpening stone is held at a desired angle between underlying support structures on a base and a securing cap. A planar edge of the stone is exposed in an adjustable channel between the stone and a slidably adjustable sidewall. The angle of the sharpening stone corresponds to correct angle for a sharpened edge on a rotary blade disposed on a hand held rotary cutter, which is inserted into the channel. By advancing the cutter through the channel an edge of the rotary blade may be honed and/or sharpened.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/572,914, filed Oct. 2, 2009, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to honers and sharpeners for blades, and, in particular, to devices and methods for sharpening blades for rotary cutters. 
       BACKGROUND 
       [0003]    Rotary cutters are used fir cutting fabric in quilt making and hobby sewing, among other uses. Such rotary cutters come in many different designs, each of which includes a handle portion and a “wheel blade” or rotary cutting blade. The various designs for rotary cutters include differing handle shapes, for ease of use or user preference, with a rotary cutting blade rotatably mounted near one end. Various designs include differing blade guard features which are intended to reduce the potential for injury to a user. 
         [0004]    The rotary cutting blades for such cutters typically come in two standard sizes, a 45 mm a diameter rotary cutting blade and a 60 mm diameter rotary cutting blade. One known problem with rotary cutters is the relatively high replacement cost of the blades for these popular fabric, craft and hobby cutting tools. Additionally, as noted in the prior art, many rotary cutting blades lack perfect roundness. 
         [0005]    Known sharpeners for rotary cutting blades include sharpeners for the large rotary blades of commercial cutters for meat slicing and the like, which are used with the motor driven blade. Also, known are smaller manual sharpeners for hand held rotary cutters, such as those disclosed in U.S. Pat. Nos. 7,238,096 and 5,660,582, the disclosures of each of which are incorporated by reference herein. However, this type of manual sharpener requires the wheel blade to be removed from the cutter and secured within a sharpener housing. This requires the user to remove and replace the blade from two different devices, which increases the downtime required for sharpening and exposes the user to potential injury while handling the unguarded blade. 
         [0006]    Accordingly there exists a need for assemblies and devices that address these problems. A system or assembly that allowed for a rotary blade to be honed or sharpened without removing the wheel blade from a hand held rotary cutter would be an improvement in the art. 
       SUMMARY 
       [0007]    Apparatus, systems and methods in accordance with the present invention are related to sharpening blades for rotary cutters. In one illustrative embodiment of a system in accordance with the present invention, an elongated sharpening stone is held at a desired angle between underlying support structures on a base and a securing cap. A planar edge of the stone is exposed in an adjustable channel between the stone and a slidably adjustable sidewall. The angle of the sharpening stone corresponds to the correct angle for a sharpened edge on a rotary blade disposed on a hand held rotary cutter, which is inserted into the channel. By advancing the cutter through the channel an edge of the rotary blade may be honed and/or sharpened. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]    It will be appreciated by those of ordinary skill in the art that the elements depicted in the various drawings are not necessarily to scale, but are for illustrative purposes only. The nature of the present invention, as well as other embodiments of the present invention may be more clearly understood by reference to the following detailed description of the invention, to the appended claims, and to the several drawings attached hereto. 
           [0009]      FIG. 1  is a perspective view of an illustrative embodiment of an assembled sharpening assembly in accordance with the principles of the present invention. 
           [0010]      FIGS. 2A and 2B  are perspective bottom and top views of the base of the embodiment of  FIG. 1 . 
           [0011]      FIGS. 3A and 3B  are perspective bottom and top views of the cap of the embodiment of  FIG. 1 . 
           [0012]      FIG. 4  is a perspective view of the sharpening stone of the embodiment of  FIG. 1 . 
           [0013]      FIGS. 5A and 5B  are perspective bottom and top views of the slide of the embodiment of  FIG. 1 . 
           [0014]      FIG. 6  is a front view of a portion of the channel of  FIG. 1 , depicting the embodiment of  FIG. 1  interacting with a hand held rotary cutter. 
       
    
    
     DESCRIPTION 
       [0015]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0016]      FIG. 1  depicts a perspective view of an illustrative embodiment of an assembled sharpening assembly  10  in accordance with the principles of the present invention. A channel C is defined between the inner sidewall of an adjustable slide  50  and an opposite sidewall defined by the assembled components of a sharpening stone  40 , resting upon support structures disposed on a base  20  and retained by a retaining cap  30 . 
         [0017]      FIGS. 2A and 2B  depict the base  20  in isolation in more detail. Base  20  may be formed as a generally planar body  200 , which may have a generally rectangular shape. A series of mounting holes  202  may be disposed along the long sides of the rectangular body, each mounting hole passing through the body  200  from the top surface  201  to the bottom surface  203 . A beveled recess may be formed in the top surface  201  around each mounting hole  202  to allow the head of a mounting screw placed therethough to reside in the recess. By inserting screws through the mounting holes, the base  20  and assembly  10  can be secured to a work surface, such as a craft table, ensuring it does not slip during use. 
         [0018]    Additionally, a number of non-slip pads or feet  204  may be disposed on the bottom surface  203  of the body  200  to reduce slipping where the assembly  10  is used without a more permanent screw-type mounting. Each pad  204  may be formed of a softer material, such as a rubber or silicon bumper type material and may be placed inside a surrounding ridge located on the bottom surface  203 . The pads  204  may be attached by a suitable adhesive, or as otherwise known in the art. 
         [0019]    In addition to the mounting holes  202 , adjustment slots  206  may be disposed through the body  200  for attachment of adjustable slide  50  to the base  20  by attachment bolts inserted through each slot  206 . Roughened or knurled areas  207  may be disposed on the upper surface  201  around each adjustment slot  206 , or at a midway point, as depicted. 
         [0020]    A support wall  210  extends upwards from the top surface  201  of the body  200 . Support wall  210  extends longitudinally, parallel to the long sides of the rectangular base  20  from one shorter side to the other. Support wall  210  has a channel side sidewall  212  which is formed as a continuous plane perpendicular to the general plane of top surface  201  and which faces adjustment slots  206  and extends from the top surface  201  to the support wall top  214  ( FIG. 6 ). As best depicted in  FIG. 6 , support wall top  214  is a planar surface placed at an angle other than parallel or perpendicular to the general plane of top surface  201 . The exact nature of this angle will be discussed further herein. The back sidewall  216  of support wall  210  is depicted as including a number of reinforcing members extending out therefrom away from the support wall to provide additional strength and stability, but it will be appreciated that other embodiments without these supports may be used. 
         [0021]    As depicted, a recess  220  may be formed in the top surface  201  of the base  20  from the back sidewall  216  towards the longitudinal side of the base, extending to a recess wall  222 , to form a space for the retaining cap  30  to reside when installed. As depicted, at each of the shorter ends of the base  20 , a shorter end wall  224  may be formed which extends across the recess  220  to provide additional support for securing the retaining cap  30 . 
         [0022]    One or more mounting structures may be disposed in the recess  220  for supporting the retaining cap  30  upon installation thereon. As depicted, the mounting structures may be a series of tabs or mesas  230  formed in a line parallel to the longitudinal axis of the base  20 . As depicted, each mesa  230  has a planar top  232  parallel to the top surface  201  of the base, with a slanted front sidewall  234  facing the back sidewall  216  of support wall  210  and a generally perpendicular rear sidewall  236 . Upon installation of the retaining cap  30 , each mesa  230  resides in a corresponding recess of the retaining cap  30 . It will be appreciated that although a single set of aligned individual mesas  230  formed as two groups of five mesas  230  are depicted that any suitable structure, such as a single elongated mesa, two aligned elongated mesas, or a single or divided wall having perpendicular or slanted sidewalls may be used. 
         [0023]    Turning to  FIGS. 3A and 3B  the retaining cap  30  is depicted in additional detail. Cap  30  is formed as an elongate body  300  having a planar upper surface  302  and an opposite planar lower surface  304 , each extending from a first end to a second end. A back sidewall  306  also extending from the first end to the second end, may be generally planar and at an angle generally perpendicular to the plane of the upper surface  302 . A front sidewall  308  (best depicted in  FIG. 6 ) has a lower portion  310  which runs parallel to back sidewall  306  to a corner  311 . From corner  311 , the front sidewall  308  extends as a planar section disposed at an angle tipped inward towards back sidewall  306  to form angled portion  312 . Angled portion  312  extends to an upper corner  313  where it intersects with upper wall  314 . Upper wall  314  may also be formed as a plane that extends from first end to second end of body  300  at an angle generally perpendicular to the plane of angled portion  302 . Upon installation to base  20 , the angle of upper wall  302  may be parallel to the angle of support wall top  214 , as depicted in  FIG. 6 . 
         [0024]    in some embodiments, an upper portion of inner sidewall, designated upper inner sidewall  318  ( FIG. 3B ) may extend from upper wall  314  to planar upper surface  302 . 
         [0025]    A number of receiving recesses  320  or sockets may formed in lower surface  304  passing into body  300  of retaining cap  30 . Each socket  320  corresponds to a mounting structure, such as a mesa  230 , on the base and allows for attachment to the base  20  by placement thereon. It will be appreciated that the recesses  320  may be formed with sidewalls that correspond to the mounting structures on the base  20 . 
         [0026]    Lower surface  304  may be sized and configured to fit within the recess  220  of base  20 , with the lower portion  310  of front sidewall  308  disposed against the back sidewall  216  of support wall  210  and the back sidewall  306  disposed against the recess wall  222 . Corner  311  may be disposed adjacent to the rear surface of support wall top  214 . ( FIG. 6 ). At either end of retaining cap  30 , a notch  309  may be formed in the lower corner of body  300  at lower surface  304  to reside on the shorter end wall  224 . This close fit between the various parts secures cap  30  on the base  20  for use. As depicted in  FIG. 6 , upon attachment, the angled portion  312  of front sidewall  308 , and upper wall  314  together with support wall top  214  may form a recess having a square cross section with an open side that extends the length of the assembly  10 . This recess is placed at an angle to the perpendicular lower portion of sidewall  212  of the support wall. 
         [0027]      FIG. 4  depicts a sharpening stone  40  which is formed as an elongated member having a square cross section that may be placed in the recess formed by the cap  30  and base  20 . As depicted in  FIG. 6 , upon installation in the recess, one side of the stone is exposed at an angle A, extending beyond the cap  30 . Angle A, when measured against the general plane of the base may be from about 75 to about 85 degrees, depending on the embodiment. In the depicted embodiment, the angle is at about 80 degrees and corresponds to the angle of the cutting edge of a rotary cutter blade. Sharpening stone  40  may be a natural or synthetic stone suitable for sharpening a blade, as known to those of ordinary skill in the art. It will be appreciated that by using a stone  40  with a square cross-section, as the exposed side of the stone  40  is worn down by use, a user may rotate the stone in the channel (by removing and replacing cap  30 ) to allow all sides of the stone to be equally used. It will further be appreciated that although a single stone is depicted, that embodiments of the present invention that utilize a series of stone having the required cross section and placed in a. common channel to form a continuous abrasive surface may be used. 
         [0028]    In addition to sharpening stones  40  with a square cross-section, it will be appreciated that sharpening stones having other shapes, such as ovoid or round, polygonal with flat or curved surfaces may be used, with the shape of the recess in the retaining cap  30  altered to match the cross-section of the selected sharpening stone  40 . Additionally, it will be appreciated that the sharpening stone  40  may be a thin stoned with a flat surface that is mounted into the plastic in the slot and may be adjustable in its angle. 
         [0029]      FIGS. 5A and 5B  depict the adjustable slide  50  in more detail. Slide  50  may be formed as an elongate body  500 . A planar section  502  may have a planar upper surface  501  and an opposite planar lower surface  503 . As depicted, one or more ridges  504  or  506  may be disposed on the upper or lower surfaces for use in adjusting the slide  50 . Bolt holes  505  pass through the planar section  502  allowing the slide  50  to be secured to the base  20  by tightening nuts ( 52 ,  FIG. 1 ) disposed on bolts passing through the adjustment slots  206  and a bolt hole  505 . Lower surface  503  may also feature roughened or knurled areas  509 , which may correspond to the similar areas  207  on the base, for additional resistance to slipping upon attachment. 
         [0030]    Along the channel side of the slide  50 , sidewall  510  is disposed. Sidewall  510  rises from the planar section  502  to a planar top surface  512 . Upon installation on base  20 , the planar top surface  512 , may have a height roughly equivalent to the planar upper surface  302  of an installed retaining cap  30  ( FIG. 6 ). The transition from planar section  502  may be an outer sidewall  514  that is generally perpendicular to the planar section  502  and top surface  512 . 
         [0031]    An inner sidewall  516  extends downwardly from top surface  512  as a plane which angles back from an upper corner to the planar portion  502 . As depicted in  FIG. 6 , the angle of inner sidewall  516  may parallel the desired angle of the exposed surface of sharpening stone  40 . Upon assembly, a channel C is formed between inner sidewall  516  of slide  50  and the support wall  210 , stone  40 , cap  30  structure. The width of the channel C may be adjusted as desired by loosening nuts  52 , sliding the slide  50  to a desired location and then retightening the nuts  52 . For storage, the slide  50  may be moved so that inner sidewall  516  contacts the stone  40 . In some embodiments, the inner sidewall  516  may include a sharpening surface, such as an additional sharpening stone or other abrasive, so that both sides of the blade of a rotary cutter can be sharpened simultaneously by contacting each sharpening surface. 
         [0032]    it will be appreciated that base  20 , retaining cap  30 , and slide  50  may be constructed from any suitable materials, including injected molded plastics having sufficient strength and rigidity. 
         [0033]    As depicted in  FIG. 6  is a front view of a portion of the channel of  FIG. 1 , depicting the embodiment of FIG I interacting with a hand held rotary cutter  60 . As depicted cutter  60  has a handle  602  with an axle  603  and a guide  605 . A wheel blade  604  is disposed on axle  603 . It will be appreciated that rotary wheel cutters are known that have a variety of different handle shapes, guide features, and guard features. The depicted rotary cutter  60  is simplified to depict common features of various hand held rotary cutters which may be sharpened by systems in accordance with the present invention and omits a number of these different features. 
         [0034]    For sharpening, a user inserts the wheel blade  604  of the cutter  60  into channel C. It will be appreciated that although the channel C is depicted as having parallel walls along its entire length, that in some embodiments, either end (or both ends) of the channel C may be widened by having the adjustable slide  50  or retaining cap  30  and stone  40  angle back from the channel C axis, in order to increase the size of the channel C opening at that portion to make it easier for a user to insert the wheel blade  604  in the channel C. 
         [0035]    The cutter  60  is held vertically over the channel and any guide  605  on the cutter may reside atop the planar upper surface  302  of cap  30  or planar top surface  512  of slide  50 . It will be appreciated that where the cutter  60  includes an “automatic” blade guard which is pushed back from the blade surface by a ruler or by the material being cut during use, the planar upper surface  302  of cap  30  or planar top surface  512  of slide  50  ma will similarly act to push back the guard to allow sharpening. 
         [0036]    The cutting edge  606  of wheel blade  604  contacts the exposed surface of stone  40 . The angle of the stone  40  created by the recess formed by cap  30  and support wall  210  is set at the desired angle for the cutting edge of the wheel blade. A user simply moves the cutter  60  along channel C to rotate the blade  604  around axle  603  to thereby hone and sharpen the cutting edge  606  on the side contacting the stone  40 . To treat the opposite side of the wheel blade  604 , the user simply physically rotates the cutter to expose the opposite cutting edge to the stone and repeats the movements. It will be appreciated that the assembly  10  may have a long axis of sufficient length to allow for complete rotation of the blade  604  in channel C to facilitate sharpening. 
         [0037]    While the present invention has been shown and described in terms of preferred embodiments thereof, it will be understood that this invention is not limited to any particular embodiment and that changes and modifications may be made without departing from the true spirit and scope of the invention as defined and desired to be protected.