Abstract:
A method and apparatus for sharpening clockwise rotating standard blades, counter-clockwise rotating standard blades and mulching style blades of either clockwise or counter-clockwise rotation is provided. The present invention comprises a base with a blade fixture which is reversible to accommodate both clockwise and counter-clockwise rotating blades. Uprights, a slide shaft, a slide bushing and a handle shaft connected to a disc grinder provide a means for setting a primary cutting angle for sharpening the primary cutting edges of a blade. An adjusting wheel rotatable attached to the handle shaft and pivotably coupled to the disc grinder provide a means for quickly and easily adjusting the cutting angle in order to accommodate sharpening the secondary cutting edges of a mulching style blade and returning the disc grinder back to its original cutting angle.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates generally to a method and apparatus for blade sharpening. More specifically, the invention provides a method and apparatus for sharpening rotary law mover blades and, in particular, sharpening both clockwise rotating and counter-clockwise rotating blades as well as sharpening both standard and mulching type lawnmower blades. 
         [0002]    As civilization has progressed from its primeval beginnings, small groups of people formed mobile communities that worked together to hunt and gather food for themselves. As their knowledge and technology advanced, they became more settled and found ways to cultivate the earth and domesticate animals for their own use and benefit without the need to be constantly on the move. As civilizations advanced further, these groups became larger communities and even large cities for trade, commerce and other activities. These activities generated greater wealth for some individuals such that they could own their own homes and have servants to take care of many, if not all, of the domestic chores such as, but not limited to, washing clothes, cleaning the household, caring for the children, preparing and cleaning up meals and so forth. At some point in time, the exact date being unknown, wealthy home owners decided to hire servants to tend the household yards in order to make more enjoyable use of the property they owned. One of the tasks required to tend the yards was to keep the lawn mowed in a neat and pleasing appearance. At that time, the process for mowing the lawns consisted of hiring a group of servants with hand sickles to cut the lawn by hand. As would be apparent to anyone considering this activity, it was a constant and laborious task to accomplish. 
         [0003]    With more advances in technology came manual hand powered lawnmowers and later gasoline powered lawnmowers. It is only in recent history that riding lawnmowers have become available for property owners personal use. While these obvious advances are plain for most individuals to see and appreciate, there have been many more advances that most people are unaware of or take no notice of. These advances include such things as a better means for leveling a power lawnmower desk so as to provide a more even appearance to a cut lawn. Wide, low air pressure filled tires allow a lawn tractor to traverse over most ground surfaces without leaving tire marks in the ground or grass. A better understanding of how to properly cut grass led to a better understanding of the proper blade cutting edge and angle that a lawnmower blade should have. A further advancement was the development of an automatic means for collecting the grass clippings and debris as the lawn was being mowed, typically known as a bagger. This allowed for easy disposal of the clippings and debris and greatly reduced the time for yard maintenance. 
         [0004]    As an alternative to collecting the grass clippings and disposing of them, came the development of what is known in the art as mulching lawnmower blades. Mulching lawnmower blades cut the grass into much smaller pieces which, when left back on the ground, decompose quickly and leave their nutrients back into the soil to aid in the growth of new grass. A standard, or non-mulching, clockwise rotating lawnmower blade  1 , as shown in  FIG. 1 , has two (2) primary cutting edges  2  and  3  that are on the same horizontal plane. There is a mounting hole  4  at the center of the blade  1  for mounting the lawn mower blade  1  to a driven shaft (not shown). A mulching clockwise rotating lawnmower blade  6 , as shown in  FIG. 2 , has four (4) cutting edges along with a mounting hole  4 . The lower two cutting edges are the primary cutting edges  2  and  3  and lie on a first horizontal plane. The top two cutting edges are secondary cutting edges  7  and  8  and lie on a second horizontal plane above the first horizontal plane. Both the standard clockwise rotating blade  1  and the mulching type clockwise rotating blade  6  have upturned ends  5  of the non-cutting primary edges which causes the cut grass to be lifted upwards above the blade  1  or  6 . With a mulching type lawnmower blade  6 , as the grass is cut for a first time with the primary cutting edges  2  and  3 , the portion of grass that was cut off is lifted by air pressure created by the rotating mulching lawnmower blade  6  and the upturned ends  5  such that the cut off portion of grass encounters the secondary cutting edges  7  and  8  which further cuts the grass portion into finer bits of grass for quicker decomposition. 
         [0005]    For many people, the use of mulching type lawnmower blades  6  is a preferable alternative as there is no need to spend time and effort to collect and then dispose of the grass clippings and it has the further advantage of returning the nutrients back into the soil for further plant growth. 
         [0006]    In addition to the standard clockwise rotating lawnmower blade  1  and the mulching type clockwise rotating lawnmower blade  6 , there are also two categories that define the type of lawnmower blade that is utilized in lawnmowers. These are the clockwise rotating lawnmower blades  1  or  6  and the counter-clockwise rotating lawnmower blades  9 , of which only the standard blade  9  is shown in  FIG. 3 .  FIG. 1  depicts a standard clockwise rotating lawnmower blade  1  and  FIG. 3  depicts a counter-clockwise rotating lawnmower blade  9 . The primary difference between a clockwise rotating lawnmower blade  1  or  6  and a counter-clockwise rotating blade  9  is that the cutting edges  2  and  3  of a counter-clockwise rotating blade  9  are on the opposites sides of a clockwise rotating blade  1  or  6  as are the upturned ends  5 . Counter-clockwise rotating mulching blades are also available similar to the mulching style blade  6  depicted in  FIG. 2  but with the secondary cutting edges  7  and  8  on the opposite sides when compared to a clockwise rotating mulching blade  6 . 
         [0007]    Cutting grass is a very abrasive process. If a user starts with a lawnmower blade, sharpened properly and at the correct cutting angle, as they mow the lawn, the process of cutting grass quickly dulls the sharp cutting edges of the blade. As the cutting edges of the blade becomes duller and duller, instead of cutting the grass the blade starts to tear the grass. This not only leads to an unappealing lawn surface, but can damage the grass thereby increasing the grass&#39; susceptibility to disease. 
         [0008]    Consequently, there is a need to sharpen the lawnmower blade or blades on a regular basis. Professional lawn care providers often sharpen their lawnmower blades after every day&#39;s use. The same is often true for those individuals responsible for the care of lawns at golf courses and recreational areas such as playgrounds and parks. Individual home owners sharpen their lawnmower blades at their own discretion. 
         [0009]    In re-sharpening a lawnmower blade, great care must be taken in a variety of areas. First and foremost is the need for safety. Regardless of the method of sharpening used, care should be taken to securely clamp or hold the lawnmower blade in place so that it does not come loose and injure someone or something. Secondly, if some form of powered sharpening mechanism is utilized, such as bench or disc grinders, there should be a means to trap and arrest any hot sparks resulting from the sharpening process in order to prevent burns or fires. Thirdly, it is important to retain the original angle of the cutting edges of both the primary,  2  and  3 , and secondary,  7  and  8 , cutting edges in order to maintain the proper grass cutting action. Fourth, when sharpening a lawnmower blade, it is important to maintain the balance of the blade. This means that in re-sharpening a lawnmower blade, all of the cutting edges on a given plane should have the same amount of material removed from them. If not, the high rotary speed of the blade in use can cause the grass to be cut unevenly leading to an unaesthetic appearance. Other areas where care is needed are well known in the art. 
         [0010]    The means for re-sharpening a lawnmower blade are varied and numerous. In one method, a user clamps a lawnmower blade in a vice and utilizes a metal file to hand sharpen the blade. However, this can lead to erroneous and uneven cutting edge angles and cause the blade to become out of balance. 
         [0011]    U.S. Pat. Pub. 2004/0142645 published on Jul. 22, 2004 to Harold Maus discloses a rotary lawnmower blade sharpener that can be utilized with a bench grinder to sharpen the primary cutting edges of a lawnmower blade. This sharpening device being distinguishable from the present invention in that there is no means provided for sharpening the secondary cutting surfaces of a mulching type blade as the fixture clamps the lawnmower blade about the center where the secondary cutting edges are located and does not allow the center of a mulching type blade to come in contact with the grinding wheel. In addition, the apparatus, as best understood and described, is only suitable for sharpening either clockwise rotating blades or counter-clockwise rotating blades but not both with the same apparatus. 
         [0012]    U.S. Pat. Pub. 2004/0244538 published on Dec. 9, 2004 to Johannes Franzen, et al. discloses an apparatus for sharpening multiple blade knives. This sharpening device being distinguishable from the present invention in that there is no means provided for sharpening the secondary cutting surfaces of a mulching type blade as the fixture clamps the lawnmower blade about the center where the secondary cutting edges are located and does not allow the center of a mulching type blade to come in contact with the grinding wheel. In addition, the apparatus, as best understood and described, is only suitable for sharpening either clockwise rotating blades or counter-clockwise rotating blades, depending upon the relative position of the fixture to the grinding medium, but not both with the same apparatus. 
         [0013]    U.S. Pat. No. 4,736,544 issued on Apr. 12, 1988 to Lawrence Greenquist discloses a blade holder for sharpening lawnmower blades. This sharpening device being distinguishable from the present invention in that there is no means provided for sharpening the secondary cutting surfaces of a mulching type blade as the fixture clamps the lawnmower blade about the center where the secondary cutting edges are located and does not allow the center of a mulching type blade to come in contact with the grinding wheel. As shown and described, the apparatus depicts the holder as being utilized to sharpen counter-clockwise rotating blades. In order to utilize the device to sharpen clockwise rotating blades, either the fixture or the grinding wheel must be physically removed and repositioned to the reverse side of the work bench which is a laborious and time consuming process. 
         [0014]    U.S. Pat. No. 6,761,623 issued on Jul. 13, 2004 to Wayne Baker discloses an apparatus and method for sharpening blades at a predetermined angle. As disclosed, the blade is mounted on a clamping fixture above a disc grinder, the disc grinder being pivotally mounted at its base. This sharpening device, as best understood by the specifications and drawings, being distinguishable from the present invention in that there is no means provided for sharpening the secondary cutting surfaces of a mulching type blade. In addition, the apparatus is only suitable for sharpening either clockwise rotating blades or counter-clockwise rotating blades, depending upon the relative position of the fixture to the grinding medium, but not both with the same apparatus. 
         [0015]    It is, therefore, an object of this invention to provide an apparatus and a method for sharpening both standard and mulching style lawnmower blades to the proper cutting edge angle. 
         [0016]    It is a further object of this invention to provide an efficient and easy apparatus and method for sharpening both clockwise rotating lawnmower blades and counter-clockwise rotating lawnmower blades. 
         [0017]    It is still a further object of this invention to assure the safety of the user and area by trapping and arresting any sparks generated during the process of re-sharpening a lawnmower blade for easy disposal later. 
         [0018]    It is still a further object of this invention to make the process of loading, sharpening all cutting edges and unloading a quick, simple and accurate process for the user. 
         [0019]    Other features and advantages of this disclosure will become apparent to one skilled in the art upon examination of the following drawings and detailed description. It is intended that all such additional features and advantages be included within the scope of the present invention. 
       SUMMARY OF THE INVENTION 
       [0020]    The present invention recognizes and addresses the various drawbacks and limitations of the various apparatuses for the sharpening of lawnmower blades of both the clockwise rotating lawnmower blade type and the counter-clockwise rotating lawnmower blade type as well as sharpening both standard type lawnmower blades and mulching type lawnmower blades. Additional objects and features of the invention are set forth in, or will be apparent to those of ordinary skill in the art, from the detailed description that follows. It should be further appreciated that modifications and variations to the specifically illustrated and disclosed features and materials hereof may be practiced in various embodiments and uses of this invention without departing from the spirit and scope thereof. Such variations may include, but are not limited to, substitutions of the equivalent means, features, and materials for those shown or discussed and the functional, or positional reversal of various parts, features or the like. 
         [0021]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and together with the description serve to explain the principles of the invention. 
         [0022]    In one exemplary embodiment, there is provided an apparatus and method for sharpening both clockwise rotating blades and counter-clockwise rotating blades at the proper angle comprising a base with a blade fixture that is easily and quickly reversible depending upon the type of blade being sharpened. By positioning the blade fixture in a first position on the base the apparatus is ready for sharpening clockwise rotating blades. By repositioning the blade fixture in a second position on the base the apparatus is ready to sharpen counter-clockwise rotating blades. 
         [0023]    Simultaneously, there is provided an apparatus and method for quickly and easily sharpening a primary cutting edge of a blade and then quickly and easily changing the angle of sharpening such that a secondary cutting edge of a mulching style blade can be properly sharpened to a proper cutting angle for the secondary cutting edge. This comprises an adjusting wheel, a spring loaded ball detent and an offset pivotable coupling tied to both the handle shaft and the sharpening mechanism. By turning the adjusting wheel, the pivotable offset coupling changes the angle of the sharpening mechanism which allows a user to easily adjust grinding angles between the primary cutting edge and the secondary cutting edge which are typically about one inch difference in height. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    A system and a method according to the invention will be described in more detail by with reference to the appended drawings in which: 
           [0025]      FIG. 1  is a perspective view of a prior art clockwise rotating standard lawnmower blade; 
           [0026]      FIG. 2  is a perspective view of a prior art clockwise rotating mulching lawnmower blade; 
           [0027]      FIG. 3  is a perspective view of a prior art counter-clockwise rotating standard lawnmower blade; 
           [0028]      FIG. 4  is a perspective view of a first embodiment of the present invention; 
           [0029]      FIG. 5  is a perspective view of the mechanism for adjusting the angle of the sharpening mechanism of the present invention; 
           [0030]      FIG. 6  is a cross sectional planar view of the adjusting wheel of the present invention; 
           [0031]      FIG. 7  is a bottom planar view of the adjusting wheel; 
           [0032]      FIG. 8  is an alternate embodiment of the handle shaft of the present invention; 
           [0033]      FIG. 9  is a perspective view of the slide bushing of the present invention; 
           [0034]      FIG. 10  is a perspective view of the blade fixture assembly of the present invention; 
           [0035]      FIG. 11  is a perspective view of the blade stop assembly of the present invention; 
           [0036]      FIG. 12  is a perspective view of the present invention with a clockwise rotating standard blade mounted into the blade fixture; 
           [0037]      FIG. 13  is a perspective view of the present invention with a clockwise rotating mulching blade mounted into the blade fixture; and 
           [0038]      FIG. 14  is a perspective view of the present invention with a counter-clockwise rotating standard blade mounted into the blade fixture. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0039]    Reference will now be made in detail to the description of the invention as illustrated in the drawings. Although the invention is described in connection with the drawings, there is no intent to limit the invention to the embodiment or embodiments disclosed therein. On the contrary, the intent is to include all alternatives, modifications, and equivalents included within the scope and spirit of the invention as defined by the appended claims. 
         [0040]    The present invention  10  is primarily concerned with a method and apparatus for sharpening lawnmower blades, and in particular, the sharpening of both clockwise and counter-clockwise rotating blades and with both standard type blades and mulching type blades. As depicted in  FIG. 4 , there is a base plate  12 . Removably mounted to the base plate  12  is a blade fixturing means  20  with two adjustable blade stop assemblies  21 , a blade fixture adaptor  22  and a sharpening mechanism rest  23 . The rest  23  preferably being made out of a resilient material such as nylon, polyurethane or the like to prevent damage to the base plate  12  and/or the sharpening mechanism  19 . Fixedly mounted to the base plate  12  are two uprights  13  and  14 . Mounted between the upper ends of the uprights  13  and  14  is a slide shaft  15 . Slideably and rotatably mounted to the slide shaft  15  is a slide bushing  16 . Perpendicularly attached to the top of the slide bushing  16  is a handle shaft  17  and on the underside of the slide bushing  16  is a removably mounted spark trap  24 . At a first end of the handle shaft  17  is attached a cushioned handle grip  18  and at a second end of the handle shaft  17  is mounted a sharpening mechanism  19 . The specific details of the means for mounting the sharpening mechanism  19  to the handle shaft  17  is discussed in greater detail below. 
         [0041]      FIG. 5  discloses the preferred embodiment for attaching the handle shaft  17  to the sharpening mechanism  19 . There is an angled bracket  25  through which a bolt  26  passes and is attached to the sharpening mechanism  19  (shown in  FIG. 4 ). On the top surface of the angled bracket  25  is a first post  27  to which is attached a first end of a pivotable coupling  28  by a screw  29 . The handle shaft  17  is connected to the base of the angled bracket  25  by a bolt  30  and nut (not shown). On the top side of the handle shaft  17  is mounted a spring loaded detent ball  31  shown in  FIG. 6 . Rotatably mounted to the handle shaft  17  by a bolt  35  is an adjusting wheel  32  which is in selective contact with the spring loaded detent ball  31  as shown in  FIG. 6 . On the top of the adjusting wheel  32  is an offset second post  33  to which is attached the second end of the pivotable coupling  28  by a screw  34 . There is also a scribe line  41  on the handle shaft  17  which is utilized in setting the primary cutting angle of the sharpening mechanism  19  (shown in  FIG. 4 ) as will be described later. 
         [0042]      FIG. 6  is a cross-sectional view of the handle shaft  17 , adjusting wheel  32 , spring loaded detent ball  31  and a portion of the pivotal coupling  28 . The adjusting wheel  32  rotates about the bolt  35  selectively engaging the spring loaded ball detent  31  on the underside of the adjusting wheel  32  in the pockets  37 . The pivotal coupling  28  pivots about the pivot ball  38 . The hole  36  in the handle shaft  17  is utilized to attach the handle shaft  17  to the angle bracket  25  (shown in  FIG. 5 ). 
         [0043]      FIG. 7  depicts the underside of the adjusting wheel  32  which has a pivot hole  39  for mounting the adjusting wheel  32  to the handle shaft  17  (shown in  FIG. 5 ), an offset hole  40  used to mount the second offset post  33  and a plurality of recessed pockets  37  for accepting the spring loaded detent ball  31  (shown in  FIG. 6 ). 
         [0044]      FIG. 8  depicts an alternate embodiment  64  for attaching the handle shaft  17  to the sharpening mechanism  19  (shown in  FIG. 4 ). In this embodiment there is a bracket  42  fixedly attached to the handle shaft  17 . The bracket  42  has a mounting hole  43  for a bolt to attach the bracket  42  to the sharpening mechanism  19  (shown in  FIG. 4 ). There is a through-hole  44  in the end of the handle shaft  17  for bolting the handle shaft  17  to the sharpening mechanism  19  (shown in  FIG. 4 ). There is a scribe line  41  on the handle shaft  17  which is utilized in setting the primary cutting angle of the sharpening mechanism  19  (shown in  FIG. 4 ) as will be described later. 
         [0045]      FIG. 9  depicts the slide bushing  16  which comprises a metal housing  45 , spark and heat resistant bushing slide  46  and a split bar clamp  47 . The split bar clamp  47  has a through-hole  48  for accepting the handle shaft  17  (shown in  FIG. 4 ) and a locking screw  49  for tightening down the split bar clamp  47  in order to clamp the handle shaft  17  (shown in  FIG. 4 ) in place. There is a plurality of line markings  50  on the face of the split bar clamp  47  around the outside edge of the through-hole  48 . The reference line  41 , shown in  FIGS. 5 and 8 , that is scribed on the handle shaft  17  (shown in  FIGS. 5 and 8 ) is used in aligning the angle of the sharpening mechanism  19  (shown in  FIG. 4 ) with the line markings  50  on the split bar clamp  47 . By rotating the handle shaft  17  (shown in  FIG. 4 ) in the split bar clamp  47 , the angle that the sharpening mechanism  19  (shown in  FIG. 4 ), in relationship to a lawnmower blade, can be determined by referring to the reference line  41  in the handle shaft  17  (shown in  FIG. 4 ) to the line markings  50  on the split bar clamp  47 . In this way, fine adjustments can be made to the resulting cutting angle of the lawnmower blade cutting edges. 
         [0046]      FIG. 10  depicts a perspective view of the blade fixture  20 . The blade fixture  20  comprises a fixture base plate  51  which has two mounting bolts  52  (only one is shown). Attached to the base plate are two uprights  53  and  54 . Attached to the uprights is an angled fixture plate  55  which has two slots  59  and  60  and a threaded hole (not shown). There are two slideable blade stop assemblies  21  (shown in  FIG. 11 ), each of which has a bar  56 , a blade stop  61 , an underside guide pin  75  that is inserted into the slot  59  or  60 , a clamping pin  76  to which is movably attached an offset cam with a lever  77 . Inserted into the threaded hole is the tapered lawnmower blade clamp  58 . Other means of clamping are well known in the art. 
         [0047]      FIG. 11  depicts one of the adjustable blade stop assemblies  21 . In use, each of the adjustable blade stop assemblies  21  is slideably attached to the fixture plate  55  with the guide pin  75  slideably inserted into the slot  59  or  60  on the fixture plate  55 . A lawnmower blade  1 ,  6  or  9  is then placed on the blade stop assemblies  21  and the blade clamp  58  is loosely secured to the fixture plate  55 . The blade stop assemblies  21  are then slid into the proper position such that the blade stop pins  61  abut the back edge of the lawnmower blade  1 ,  6  or  9 . The offset cams  77  are then rotated in order to secure the blade stop assemblies  21  to the fixture plate  55 . The blade clamp  58  is then tightened to secure the lawnmower blade  1 ,  6  or  9  to the blade fixture  20 . 
         [0048]      FIG. 12  depicts a perspective view of the apparatus  10  with a standard clockwise cutting lawnmower blade  1  clamped into the blade fixture  20  by the blade clamp  58  with the blade stop pin  61  abutting the blade  1 . The arrow  63  depicts the relative available movement of the sharpening mechanism  19  along the slide shaft  15 . 
         [0049]      FIG. 13  depicts the apparatus  10  with a clockwise rotating mulching type lawnmower blade  6  installed on the blade fixture  20 . To sharpen a clockwise rotating mulching lawnmower blade  6  with the apparatus  10 , a user removes the blade clamp  58 , places the blade  6  horizontally on the blade stop assemblies  21  (as shown in  FIG. 10 ) and loosely secures the blade clamp  58  onto the blade fixture  20 . The user then slides the blade stop assemblies  21  to abut the blade stop pins  61  to the lawnmower blade  6  and then secures the blade stop assembly  21  by rotating the offset cam  77 . The user then tightens down the blade clamp  58 . If not already preset, the user then loosens the locking screw  49  in the slit bar clamp  47  (as shown in  FIG. 9 ), rotates the handle shaft  17  which rotates the attached sharpening mechanism  19  until the sharpening mechanism  19  is parallel with the primary cutting edge  2  or  3  and retightens the locking screw  49  to keep the handle shaft  17  and sharpening mechanism  19  in the proper position for sharpening the primary lawnmower blade cutting edge  2  or  3 . Once the proper cutting angle is set for either cutting edge  2  or  3 , the user can sharpen the primary blade cutting edge  2  or  3  by powering up the sharpening mechanism  19  and moving the sharpening mechanism  19  across the primary cutting edge  2  or  3  as indicated by the arrow  63 . 
         [0050]    If the user makes no adjustments to the cutting angle of the sharpening mechanism  19 , attempting to sharpen the secondary cutting edges  7  or  8  of the mulching type lawnmower blade  6  will result in an improper angle of the secondary cutting edges  7  or  8  as the secondary cutting edges  7  and  8  are approximately one inch above the plane of the primary cutting edges  2  and  3  thereby changing the angular relationship of the sharpening mechanism  19  to the secondary cutting edge  7  or  8 . In its preferred embodiment, to adjust the angle of the sharpening mechanism  19  quickly and easily, in order to sharpen the secondary cutting edges  7  and  8  of a mulching type lawnmower blade  6 , a user turns the adjusting wheel  32  which in turn causes the offset pivotal coupling  28  to push outward or pull backward, depending upon the direction the adjusting wheel  32  is turned, which causes the sharpening mechanism  19  to re-angle itself relative to the lawnmower blade  6 . Once the sharpening mechanism  19  is set at the correct angle for the secondary cutting edge  7  or  8 , the user then powers up the sharpening mechanism  19  and moves the sharpening mechanism  19  along the direction indicated by the arrow  63  to sharpen the secondary cutting edge  7  or  8 . 
         [0051]    The user then removes the blade clamp  58 , rotates the lawnmower blade  6  180 degrees, repositions the lawnmower blade  6  parallel to the blade fixture  20  and abutting the blade stop  61  and re-attaches the blade clamp  58 . The user can then power up the sharpening mechanism  19  to sharpen the other secondary cutting edge  7  or  8 , turn the adjusting wheel  32  back to its original position and re-sharpen the other primary cutting edge  2  or  3 . When the blade sharpening is completed and the sharpened lawnmower blade  6  removed from the blade fixture  20 , the spark trap  24  can be removed and the trapped debris properly disposed of. 
         [0052]    In the alternate handle design  64  depicted in  FIG. 8 , once the angle of the sharpening mechanism  19  is set, the user can then utilize the apparatus  10  to clamp a standard lawnmower blade  1  or  9  into the blade fixture  20 , sharpen one of the primary edges  2  or  3  of the lawnmower blade  1  or  9 , unclamp the lawnmower blade  1  or  9  from the blade fixture  20 , rotate the blade  1  or  9  180 degrees, re-clamp the blade  1  or  9  and sharpen the other primary edge  2  or  3  and then unclamp the blade  1  or  9 . With this alternative handle  64 , in order to sharpen the secondary cutting edges  7  and  8  of a mulching type blade  6  the user needs to sharpen both primary edges  2  and  3  and then loosen the split bar clamp  47  by loosening the screw  49  (shown in  FIG. 9 ), rotate the handle shaft  17  to the proper angle and tighten the split bar clamp screw  49  thereby tightening the split bar clamp  47  about the handle shaft  17 . The user can then sharpen the secondary cutting edges  7  and  8  by powering up the sharpening mechanism  19  and drawing the sharpening mechanism  19  over a secondary cutting edge  7  or  8 , unclamping the blade  6 , rotate the blade  6  180 degrees, re-clamping the blade  6  in the blade fixture  20 , powering up the sharpening mechanism  19  and drawing the sharpening mechanism  19  over the other secondary edge  7  or  8  and then unclamping the blade  6 . 
         [0053]      FIG. 14  depicts the apparatus  10  setup to sharpen counter-clockwise rotating blades  9 . To convert the apparatus  10  from being utilized to sharpen clockwise rotating blades  1  or  6  to utilizing the apparatus  10  to sharpen counter-clockwise rotating blades  9 , or vice versa, a user removes the two bolts  52  (only one of which is shown in  FIGS. 4 and 10 ) which attach the blade fixture  20  to the base  12 , rotates the blade fixture  20  180 degrees and re-attaches the bolts  52  through the blade fixture  20  to secure the blade fixture  20  into its new position on the base plate  12 . Counter-clock wise rotating blades, of either the standard or mulching type can now be sharpened in a manner similar the method described above for sharpening clockwise rotating blades. 
         [0054]    The tapered blade fixture adapter  22 , shown in  FIG. 4 , is inserted into the blade mounting hole  4 , shown in  FIGS. 1 ,  2  and  3 , when the blade mounting hole  4  is larger than the blade clamp  58 . This allows the blade clamp  58  to secure the blade and fixture adapter  22  to the blade fixture  20 . 
         [0055]    Although the preferred embodiments of the invention has been described using specific terms, devices and drawings, such description is for illustrative purposes only. The words and terminology used are words of description rather than of limitation. It is to be understood that changes and variations may be made by those of ordinary skill in the art without departing from spirit and scope of the present invention, which is set forth in the following claims. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiments contained herein.