Patent Publication Number: US-2018036900-A1

Title: Arbors for circular saws and associated systems and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims priority to U.S. Provisional Patent Application No. 62/370,104, entitled “ARBORS FOR CIRCULAR SAWS AND ASSOCIATED SYSTEMS AND METHODS,” filed Aug. 2, 2016, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The following disclosure relates generally to arbors for circular saws and, more particularly, to arbors for securely attaching saw blades to drive shafts of circular saws and associated systems and methods. 
     BACKGROUND 
     A variety of existing circular saws include a motor-driven, rotatable drive shaft. Typically, a saw blade is removably coupled to the drive shaft via an arbor. The arbor is generally a two-piece device that includes an interior portion and an exterior portion. The interior and exterior portions are positioned on opposite sides of a central hole in the saw blade, with the interior portion positioned between the saw blade and a body of the saw. A bolt can be extended through the exterior and interior portions of the arbor and the central hole in the saw blade, and threaded into the drive shaft to secure the saw blade to the drive shaft. A friction fit or a shaped opening (e.g., a knockout opening) is typically used to reduce slippage between the saw blade and the drive shaft. With a friction fit, the bolt is tightened to drive the interior and exterior portions of the arbor towards each other and press against the blade positioned therebetween. If the bolt is insufficiently tightened and/or if the blade is subjected to significant drag forces, the blade can slip with respect to the drive shaft and the arbor. Slippage of the blade can interrupt cutting operations and/or produce inaccurate or otherwise defective cuts. 
     With knockout openings, the interior portion of the arbor includes an engagement feature that is positionable within a complimentary-shaped knockout opening in the saw blade. The engagement feature and the knockout opening often have complimentary diamond shapes, and the engagement feature extends outwardly, away from the drive shaft, and into the knockout opening to engage the blade. The engagement feature is generally designed to extend outwardly a distance that is less than or equal to the thickness of the saw blade. The bolt can then drive the interior and exterior portions of the arbor toward each other and against the blade, without the engagement feature contacting the exterior portion and preventing the interior portion and exterior portion from securely contacting the blade. In most cases, the diamond shaped engagement feature and the corresponding knockout opening can help reduce slippage between the blade and the drive shaft. Slippage can still occur, however, if the engagement feature does not stay positively engaged within the blade via the knockout opening. If a relatively thick saw blade is used, for example, the engagement feature may not extend a significant enough depth into the knockout opening. Excessive forces on the blade and/or insufficient tightening of the bolt can then result in movement of the blade that disengages the engagement feature from the knockout opening and results in blade slippage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are isometric front and rear views, respectively, of an arbor configured in accordance with an embodiment of the present technology. 
         FIG. 2A  is an isometric front view of an arbor coupler configured in accordance with an embodiment of the present technology, and  FIG. 2B  is an isometric rear view of an arbor flange configured in accordance with an embodiment of the present technology. 
         FIG. 3  is an exploded isometric view of an arbor positioned for engagement with a saw blade in accordance with an embodiment of the present technology. 
         FIG. 4  is a cross-sectional overhead view of an arbor engaged with a saw blade in accordance with an embodiment of the present technology. 
         FIG. 5A  is an isometric view of a circular saw blade mounted to a saw in accordance with an embodiment of the present technology, and  FIG. 5B  is an exploded isometric view illustrating installation of a circular saw blade on a circular saw via an arbor configured in accordance with an embodiment of the present technology. 
     
    
    
     DETAILED DESCRIPTION 
     The following disclosure describes various embodiments of arbors for circular saws and associated systems and methods. In several embodiments, an arbor includes a coupler and a flange. The coupler can include an interior mounting face and an engagement feature, and the engagement feature can be shaped to extend through an opening in a saw blade. The flange can include an exterior mounting face and a recess, and the recess can be shaped to at least partially receive the engagement feature. The flange and the coupler can be configured to fixedly attach the saw blade to a drive shaft of the circular saw, with the saw blade clamped at least partially between the interior mounting face and the exterior mounting face. 
     In other embodiments, the arbors described herein and the associated devices, systems and methods can have different configurations, components, and/or procedures. Still other embodiments may eliminate particular features, components and/or procedures. A person of ordinary skill in the relevant art, therefore, will understand that the present technology, which includes associated devices, systems, and procedures, may include other embodiments with additional elements or steps, and/or may include other embodiments without several of the features or steps shown and described below with reference to  FIGS. 1-5B . 
     As discussed above, existing arbors may not adequately prevent slippage of a saw blade relative to a corresponding drive shaft. The present technology includes several embodiments of arbors and associated systems and methods that have engagement features for significantly reducing or even preventing the opportunity for slippage between a saw blade and the arbor. In some embodiments, such arbors can be referred to as “slipless arbors.” As used herein, the term “slipless arbors” refers to arbors that prevent or significantly reduce opportunities for slippage between an arbor and an associated saw blade. Certain details are set forth in the following description and  FIGS. 1-5B  to provide a thorough understanding of various embodiments of the disclosure. To avoid unnecessarily obscuring the description of the various embodiments of the disclosure, other details describing well-known structures and systems often associated with arbors, circular saw blades, circular saws, and the components or devices associated with the manufacture of conventional arbors, circular saw blades and circular saws are not set forth below. Moreover, many of the details and features shown in the Figures are merely illustrative of particular embodiments of the disclosure. Accordingly, other embodiments can have other details and features without departing from the spirit and scope of the present disclosure. In addition, the various elements and features illustrated in the Figures may not be drawn to scale. Furthermore, various embodiments of the disclosure can include structures other than those illustrated in the Figures and are expressly not limited to the structures shown in the Figures. 
     In the Figures, identical reference numbers identify identical, or at least generally similar, elements. To facilitate the discussion of any particular element, the most significant digit or digits of any reference number refers to the Figure in which that element is first introduced. For example, element  102  is first introduced and discussed with reference to  FIG. 1A . 
       FIG. 1A  is an isometric front view of an arbor  100  configured in accordance with an embodiment of the present technology. In the illustrated embodiment, for example, the arbor  100  includes an exterior portion or flange  102  positioned toward a distal end  103  and an interior portion or coupler  104  positioned toward a proximal end  105 . When the flange  102  and the coupler  104  are mated as shown in  FIG. 1A , an annular gap  106  exists between the flange  102  and the coupler  104 . As described in more detail below, the gap  106  is configured to receive a portion of a saw blade to secure the blade to a drive shaft. 
       FIG. 1B  is an isometric rear view of the arbor  100  of  FIG. 1A . Referring to  FIGS. 1A and 1B  together, the arbor flange  102  includes a flange bore  108   a  and an exterior face  109 , and the arbor coupler  104  includes a coaxial coupler bore  108   b . The flange bore  108   a  and the coupler bore  108   b  are identified collectively as the arbor bore  108 . As further described below, a bolt can extend through the bore  108  to secure a saw blade to a drive shaft of a circular saw via the arbor  100 . 
     In the illustrated embodiment, the coupler bore  108   b  includes two opposing flat surfaces  112  (only one flat surface  112  visible in  FIG. 1B ). The coupler bore  108   b  can be sized and shaped so that the flat surfaces  112  securely contact complimentary flat surfaces on the drive shaft to prevent rotation of the coupler  104  with respect to the drive shaft. The coupler  104  also includes an interior face  115  at the proximal end  105 , and a shoulder  117  within the coupler bore  108   b . The shoulder  117  can be positioned to abut a corresponding shoulder on the drive shaft of the circular saw. 
       FIG. 2A  is an isometric front view of the coupler  104  configured in accordance with an embodiment of the present technology. In the illustrated embodiment, the coupler  104  includes a body  202  having a cylindrical portion  204  and an annular portion  206 . The coupler bore  108   b  extends through the cylindrical portion  204  and the annular portion  206 , with the flat surfaces  112  extending within the cylindrical portion  204 . The annular portion  206  includes an interior mounting face  208  and an engagement feature  210 . The engagement feature  210  extends outwardly, away from the interior mounting face  208 . The engagement feature  210  includes a forward face  211 , an inner wall  214 , and a hexagonal wall  212  having six flat portions. 
       FIG. 2B  is an isometric rear view of the flange  102  configured in accordance with an embodiment of the present technology. In the illustrated embodiment, the flange  102  includes a body  216  having a circular cylindrical portion  218  and a coaxial annular portion  220 . In some embodiments, the cylindrical portion  218  is sized and configured for a close-fit with the inner wall  214  of the engagement feature  210 . The flange bore  108   a  extends through the cylindrical portion  218  and the annular portion  220 , and the annular portion  220  includes an exterior mounting face  222  and a recess  224 . The recess  224  extends into the annular portion  220  adjacent to the cylindrical portion  218  and has a hexagonal shape at least partially defined by a hexagonal outer wall  226  having six flat portions. The recess  224  is shaped to engage the engagement feature  210  and, as described in more detail below, the engagement feature  210  can be at least partially received in the recess  224 . Although the engagement feature  210  includes the hexagonal wall  212  and the recess  224  includes the hexagonal outer wall  226 , in other embodiments engagement features and corresponding recesses can include other shapes (e.g., oval, star, square, etc.). 
       FIG. 3  is an exploded isometric view of the arbor  100  positioned for engagement with a saw blade  300  in accordance with an embodiment of the present technology. In the illustrated embodiment, the saw blade  300  includes a central opening  302  positioned in a cupped central mounting portion  304  and shaped to receive the engagement feature  210 . Specifically, the opening  302  has a hexagonal shape that is sized to snugly receive the engagement feature  210 . The saw blade  300  also includes an exterior planar surface  305 . In the illustrated embodiment, the saw blade  300  can be mounted on the arbor  100  with the exterior face  109  of the flange  102  coplanar with the exterior planar surface  305 . In other embodiments, the exterior face  109  can be recessed within the cupped portion  304  (i.e., offset from the exterior planar surface  305  in a direction toward the proximal end  105  of the arbor  100 ). 
       FIG. 4  is a cross-sectional overhead view of the arbor  100  engaged with the saw blade  300  in accordance with an embodiment of the present technology. In the illustrated embodiment, the arbor  100  securely engages the saw blade  300  to reduce or prevent slippage of the blade  300  relative to the arbor  100 . In particular, the engagement feature  210  of the coupler  104  extends through the opening  302  in the saw blade  300  and into the recess  224  of the flange  102 , “locking” at least a portion of the saw blade  300  between the interior mounting face  208  and the exterior mounting face  222 . The hexagonal opening  302  of the saw blade is aligned in a close-fit with the hexagonal wall  212  of the engagement feature  210 , preventing rotation of the saw blade  300  with respect to the arbor  100 . Additionally, the hexagonal wall  212  of the engagement feature  210  is aligned in a close-fit with the hexagonal outer wall  226  of the flange  102 , preventing rotation of the flange  102  with respect to the coupler  104 . Moreover, the interior mounting face  208  and the exterior mounting face  222  are driven toward each other by a bolt (not shown in  FIG. 4 ) and clamp the saw blade  300  therebetween. 
     In the illustrated embodiment, the engagement feature  210  extends past the opening  302  in the saw blade  300 , such that the saw blade  300  is axially offset from the forward face  211  of the engagement feature (i.e., offset in a direction along an axial axis A). The axial offset between the saw blade  300  and the forward face  211  of the engagement feature  210  can help to prevent the saw blade  300  from moving off of the engagement feature  210 , and thereby significantly reduce the opportunity for slippage between the saw blade  300  and the arbor  100 . Specifically, when the saw blade  300  is positioned on the coupler  104  with the engagement feature  210  extending through the hexagonal opening  302 , the close fit of the hexagonal opening  302  and the hexagonal wall  212  prevents rotation of the saw blade  300  with respect the arbor  100 . Absent deformation of the saw blade  300  or the arbor  100 , slippage of the saw blade  300  with respect to the arbor  100  is only possible when the engagement feature  210  moves out of the opening  302 . The axial offset of the saw blade  300  and the forward face  211  of the engagement feature  210  reduces undesired movement of the engagement feature  210  out of the opening  302 , and thereby reduces the opportunity for slippage. In several embodiments, the axial offset between the saw blade  300  and the forward face  211  of the engagement feature  210  can be at least partially dependent on an axial offset between the forward face  211  and the interior mounting face  208 . In some embodiments, the axial offset between the forward face  211  and the interior mounting face  208  can be 3 mm. In other embodiments, the axial offset between the forward face  211  and the interior mounting face  208  can be between 1 mm and 5 mm, or between 1 mm and 30 mm. 
       FIG. 5A  is an isometric view of the circular saw blade  300  mounted to a saw  500  in accordance with an embodiment of the present technology. In some embodiments, the saw  500  can include one or more handles  506  and a motor assembly  508 . The motor assembly  508  is operative to drive the saw blade  300  via a drive shaft  502 .  FIG. 5B  is an exploded isometric view illustrating a method of mounting the saw blade  300  to the circular saw  500  via the arbor  100 . In the illustrated embodiment, the saw blade  300  is secured to the drive shaft  502  of the circular saw  500  via a bolt  504 . Specifically, the bolt  504  can extend through the bore  108  ( FIGS. 1A-4 ) of the arbor  100 , through the opening  302  in the saw blade  300  ( FIGS. 3 and 4 ), and threadably engage a corresponding threaded hole in the drive shaft  502 . The bore  108  can be shaped to receive a head of the bolt  504  so that the head does not extend beyond the exterior face  109  of the flange  102 . As noted above, the saw blade  300  can be mounted on the arbor  100  with the exterior face  109  of the flange  102  flush with the exterior planar surface  305 , or recessed within the cupped portion  304 . In such embodiments, no portion of the arbor  100  or the bolt  504  extends beyond the exterior planar surface  305  of the saw blade  300 , and the arbor  100  can provide flush-cut capabilities for associated circular saws. For example, the arbor  100  can mount the saw blade  300  such that no portion of the associated saw or any other component extends beyond the exterior planar surface  305 . When mounted in such a manner, the associated saw can cut along a cutting path that is directly adjacent to a planar surface. In several embodiments, the arbor  100  can provide flush-cut capabilities for saws that are at least generally similar to those described in U.S. patent application Ser. No. 13/817,765, filed Aug. 18, 2011, which is incorporated herein by reference in its entirety. 
     In addition to eliminating or significantly reducing slippage and providing flush-cut capabilities, arbors configured in accordance with the present technology are expected to reduce or eliminate saw path deflection during cutting operations. When a force is applied to a conventional circular saw to advance the saw along a cutting path, the saw will tend to stray or deflect away from the direction of the force at a slight angle, and thereby deviate from the intended cutting path. Without being bound by any theory or mechanism of action, the inventor believes that the arbor  100  can include dimensions that help to reduce or eliminate such saw path deflection. More particularly, the arbor  100  can be constructed with the gap  106  ( FIG. 1 ) positioned to align the blade  300  in a cutting plane that reduces saw path deflection. It is believed that the location of the cutting plane that produces the minimum saw path deflection can depend on one or more features of the circular saw or its associated components. For example, it is believed that the axis of rotation of a motor on the circular saw can influence the proper positioning of the cutting plane for reduced saw path deflection. 
     The inventor has determined that particular dimensions of the arbor  100  can position the saw blade  300  at a location that significantly reduces or eliminates saw path deflection. For example, in one embodiment, an axial distance from the shoulder  117  of the coupler  104  to the interior mounting face  208  can be between 20 mm and 35 mm, or about 27.5 mm. The inventor has determined that for particular circular saws, an axial offset of 27.5 mm between the shoulder  117  and the interior mounting face  208  significantly reduces saw path deflection. In other embodiments, the distance between the shoulder  117  and the interior mounting face  208  can be larger or smaller than 27.5 mm. For example, the distance between the shoulder  117  and the interior mounting face can be between 5 mm and 100 mm or between 20 mm and 40 mm. 
     In some embodiments, other dimensions can determine the proper positioning of a blade to reduce or eliminate saw path deflection. For example, in one embodiment, an axial distance between the interior face  115  of the coupler  104  and the interior mounting face  208  can be 32.5 mm to provide significantly reduced saw path deflection. In other embodiments, the distance between the interior face  115  of the coupler  104  and the interior mounting face  208  can be larger or smaller than 32.5 mm (e.g., between 5 mm and 100 mm or between 25 mm and 45 mm). 
     The arbor  100  and associated components described herein can be constructed using a variety of materials and manufacturing methods known in the art. For example, the arbor  100  can be machined from metal and/or metal alloy stock materials (e.g., steel or aluminum) via a milling machine, a vertical or horizontal machining center, a multi-tasking machine, or other manufacturing machines and/or tools. In some embodiments, the arbor  100  can be cast formed via metal and/or metal alloys. In other embodiments, the arbor  100  can be formed from plastics, composites, metals and/or other materials via a 3D printer or via other manufacturing methods. 
     The present technology can include a variety of methods for reducing slippage between an arbor and a circular saw blade. A particular method can include forming an arbor having an engagement feature shaped to extend through an opening in a circular saw blade. Forming the arbor can include forming a coupler that includes the engagement feature, and forming a flange having a recess shaped to receive the engagement feature. 
     From the foregoing, it will be appreciated that specific embodiments have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the present technology. Those skilled in the art will recognize that numerous modifications or alterations can be made to the components or systems disclosed herein. For example, an embodiment described above included an interior portion or coupler having an engagement feature, and an exterior portion or flange having a recess. In other embodiments, an interior portion or coupler can include a recess and an exterior portion or flange can include an engagement feature shaped to be at least partially received in the recess of the coupler. Moreover, certain aspects of the present technology described in the context of particular embodiments may be combined or eliminated in other embodiments. Furthermore, while advantages associated with certain embodiments have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the present technology. Accordingly, the inventions are not limited except as by the appended claims.