Patent Publication Number: US-2005132578-A1

Title: Saw

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to saws and, more particularly, to hand saws configured for making “flush cuts” and starter saws configured for starting cuts from within a plane of the material being cut.  
      Saws capable of making “flush cuts” are known in the art. Such saws are capable of cutting through a protrusion that is perpendicular to a surface in manner so that the cut is “flush” to the surface. These saws are also useful for making cuts in locations having limited clearance, such as at a corner where the planes of two surfaces meet at a 90 degree angle. Some amount of clearance is needed for the saw handle and the user&#39;s hand, which makes flush cuts of this kind difficult with a conventional saw. Therefore, many saws designed for making flush cuts include saw blades that are of sufficient flexibility to permit the blade to be “flexed” so that a portion of the blade is parallel to and flush against a surface adjacent to the material being cut. These blades also typically have little or no lateral inclination to the saw teeth, so as to avoid marring the adjacent surface. Without sufficient flexibility of the blade, clearance needed for the saw handle or user&#39;s hand may not permit a sufficiently flush cut. Known prior art flush-cutting blades have a generally straight cutting edge that is not suitable for starting cuts from within the plane of the material being cut. The distal tip of the blade may be used to start a cut from within the plane of the material, but this is an awkward and difficult exercise and also results in premature wear of the teeth at end of the blade. Known prior art flush-cutting saws also lack appropriate adjustability of the blades relative to the handles to allow access in tight locations.  
      Starter saws capable of starting cuts from within the plane of the material being cut (i.e, not starting from an edge of the material) are also known in the art. Some of these saws include a convex cutting edge that allows the cut to be started from within the plane of the material being cut. However, such saws typically include some set or lateral inclination to the teeth, which makes them undesirable for use in a flush cutting operation. Such saws also lack any means for accurately controlling the depth of the cut.  
     SUMMARY OF THE INVENTION  
      In general, a saw of the present invention comprises a generally planar saw blade, a handle, and a depth control guide. The saw blade has a proximal end and a distal end. The blade has an arcuate cutting edge extending along at least a portion of the saw blade between its proximal end and distal end. The blade has a shank portion adjacent its proximal end. The handle is adapted for hand-engagement by a user. The shank portion of the saw blade is pivotally connected to the handle in a manner to permit pivoting movement of the saw blade relative to the handle in a plane of the saw blade. The depth control guide comprises an arcuate depth control surface. The arcuate depth control surface is adapted for engagement with a surface of material being cut by the saw in a manner to control cutting depth. The arcuate depth control surface has a curvature that approximates a curvature of the arcuate cutting edge of the saw blade. The depth control guide is adjustably connected to the saw blade in a manner so that the distance between the arcuate depth control surface and the arcuate cutting edge of the blade can be selectively adjusted to achieve a desired cutting depth.  
      In another aspect of the invention, a saw comprises a generally planar saw blade and a depth control guide. The saw blade has an arcuate cutting edge with a fixed radius of curvature. The depth control guide comprises an arcuate depth control surface that is configured for engagement with a surface of material being cut in a manner to control cutting depth. The depth control guide is movably connected to the saw blade in a manner so that a distance between the arcuate depth control surface and the arcuate cutting edge of the saw blade can be selectively adjusted to achieve a desired cutting depth. The arcuate depth control surface has an adjustable radius of curvature.  
      In still another aspect of the invention, a saw comprises a generally planar saw blade and a depth control guide. The saw blade is formed of a ferromagnetic material and has a cutting edge. The depth control guide has a depth control surface that is adapted for engagement with a surface of material being cut in a manner to control cutting depth. The depth control guide has at least one magnet. The depth control guide is adjustably connected to the saw blade via the magnet in a manner so that a distance between the depth control surface and the cutting edge of the saw blade can be selectively adjusted to achieve a desired cutting depth.  
      In a further embodiment of the present invention, a saw comprises a generally planar saw blade and a depth control guide. The saw blade has an arcuate cutting edge. The depth control guide comprises an arcuate depth control surface that is configured for engagement with a surface of material being cut in a manner to control cutting depth. The arcuate depth control surface has a curvature that approximates a curvature of the arcuate cutting edge of the saw blade. The depth control guide is adjustably connected to the saw blade in a manner so that a distance between the arcuate depth control surface and the arcuate cutting edge of the saw blade can be selectively adjusted to achieve a desired cutting depth.  
      Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a saw of the present invention, with a handle portion shown in a first position;  
       FIG. 2  is an exploded perspective view of the saw of  FIG. 1 , showing the assembly of its various components;  
       FIG. 3  is a side elevational view of the saw of  FIG. 1 , with the handle shown in a second position;  
       FIG. 4  is a top plan view of the saw of  FIG. 3 ;  
       FIG. 5  is a top plan view of the depth control guide, removed from the saw of  FIG. 3 ;  
       FIG. 6  is a front end elevational view of the saw of  FIG. 3 ; and  
       FIG. 7  is a side elevational view of an alternate embodiment of a saw of the present invention. 
    
    
      Reference characters used in these Figures correspond to reference characters used throughout the following detailed description of the preferred embodiments.  
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      A saw of the present invention is represented in its entirety in  FIG. 1  by the reference numeral  10 . In general, the saw  10  comprises a saw blade  12 , a handle  14  and a depth control guide  16 . The saw blade  12  is generally planar and has a proximal end  18  and a distal end  20 . Preferably, the blade  12  has an arcuate cutting edge  22 , which extends along the saw blade between its proximal and distal ends. As best shown in  FIG. 2 , the proximal end  18  of the blade  12  includes a shank portion  24 . The handle  14  is adapted for hand-engagement by a user (not shown). Preferably, the handle  14  and the shank portion  24  of the blade  12  are pivotally connected to one another in a manner to permit pivoting movement of the blade  12  relative to the handle  14  in a plane of the blade  12 . The depth control guide  16  comprises an arcuate depth control surface  30 , which is preferably generally perpendicular to the plane of the saw blade  12 . As explained hereinafter, the arcuate depth control surface  30  is adapted for abutting engagement with a surface (not shown) of material being cut with the saw  10  in a manner to control cutting depth. As explained below, the depth control guide  16  is adjustably connected to the blade  12  in a manner so that a distance between the arcuate depth control surface  30  and the arcuate cutting edge  22  of the blade  12  can be selectively adjusted to achieve a desired cutting depth.  
      As shown in the Figures, the handle  14  resembles a clevis with a slot dimensioned to receive the shank portion  24  of the blade  12  therein. A pivot pin  32  engages both the handle  14  and the shank portion  24  in a manner to permit pivoting movement of the blade  12  relative to the handle  14  in a plane of the blade  12 . Preferably, the saw  10  further comprises a locking mechanism  34  including a hand-operable locking member  36  that is operatively connected to the handle  14  in manner so that the relative positions of the saw blade  12  and handle  14  can be locked and unlocked by rotating the locking member  36  relative to the handle  14  about a locking pin  38 . The pivot pin  32  includes a hole  40  (see  FIG. 2 ) that is sized to receive the locking pin  38 , and thereby secure the pivot pin  32 , locking member  36  and locking pin  38  to the handle  14 . The locking member  36  includes a cam surface  41  that firmly engages an outer surface  42  of the handle  14  (when the locking member  36  is in its locked position) and squeezes the shank portion  24  between the two sides of the clevis of the handle  14  with enough force to maintain the relative positions of the blade  12  and handle  14  by friction. The locking member  36  is rotatable by hand (i.e., without tools) to an unlocked position, wherein the cam surface  41  disengages the outer surface  42  of the handle  14  (or at least reduces its force against the handle) so that the blade  12  may be pivoted relative to the handle  14 . Adjustment of the blade  12  relative to the handle  14  in this manner allows access in restrictive places.  
      As best shown in  FIG. 3 , the cutting edge  22  of the blade  12  has an arcuate (preferably convex) configuration. The arcuate cutting edge  22  preferably has a radius of curvature that facilitates starting a cut from within the plane of the material being cut. The pivotal connection between the blade  12  and the handle  14  permits adjustment of the blade  12  to allow tangential contact of the arcuate cutting edge  22  with the work piece at a variety of positions along the blade length.  
      Preferably, the saw blade  12  is of a flexible material, e.g., relatively thin gauge steel, that permits flexion of the blade  12  in a plane that is generally perpendicular to the plane of the saw blade and that is also generally parallel to at least a portion of the cutting edge (i.e., side to side relative to the line of cut). Again, this flexibility permits flush cutting operations. Preferably, there is little or no lateral inclination to the cutting teeth so as to avoid marring the adjacent surface during a flush cutting operation.  
      The arcuate cutting edge  22  of the blade  12  will have a fixed radius of curvature R 1 . Again, the arcuate depth control surface  30  of the depth control guide  16  is adapted for abutting engagement with a surface of the material being cut in a manner to control cutting depth, and the depth control guide  16  is preferably adjustable relative to the blade  12  so that the distance between the arcuate depth control surface  30  and the arcuate cutting edge  22  of the blade  12  can be selectively adjusted to achieve a desired cutting depth. As best shown in  FIG. 3 , the arcuate depth control surface  30  preferably has a curvature that approximates a curvature of the arcuate cutting edge  22  of the saw blade  12 . Thus, the spacing between the arcuate cutting edge  22  and the arcuate depth control surface  30  will be substantially constant along the entire length of the arcuate cutting edge  22 .  
      In the preferred embodiment of the invention, at least a portion of the depth control guide  16  is of a flexible and resilient material (e.g., molded Nylon) that permits flexion of the arcuate depth control surface  30  in a plane that is generally parallel to a plane of the saw blade (i.e., side to side relative to the line of cut). Thus, the depth control guide  16  will flex along with the blade  12  even when the blade  12  is flexed substantially during a flush cutting operation.  
      Preferably, the arcuate depth control surface  30  of the depth control guide  16  has an adjustable radius of curvature R 2 . As explained below, the depth control guide  16  is preferably configured in a manner so that the radius of curvature R 2  of the arcuate depth control surface  30  decreases as the depth control guide  16  is moved relative to the saw blade  12  in a direction (upwardly as viewed in  FIG. 3 ) that increases the distance D between the arcuate depth control surface  30  and the arcuate cutting edge  22 , and so that radius of curvature R 2  of the arcuate depth control surface  30  increases as the distance D decreases. Thus, the radius of curvature R 2  of the arcuate depth control surface  30  varies in a manner so that an arc of curvature of the arcuate depth control surface  30  will remain substantially concentric with an arc of curvature of the arcuate cutting edge  22  as the depth control guide  16  is moved relative to the saw blade  12  to adjust cutting depth. This ensures a substantially constant distance between the arcuate depth control surface  30  and the arcuate cutting edge  22  along substantially the entire length of the arcuate cutting edge  22 .  
      Again, at least a portion of the depth control guide  16  is of a flexible and resilient material (e.g., molded Nylon) that permits flexion of the arcuate depth control surface  30  in a plane that is generally parallel to a plane of the saw blade. This material also preferably permits some degree of flexion and resilience with a plane of the depth control guide  16 , generally parallel to the blade. Preferably, the depth control guide  16  is molded in a manner so that the arcuate depth control surface  30  has a nominal radius of curvature (i.e., a radius of curvature at equilibrium, when not undergoing any elastic deformation) that approximates the radius of curvature R 1  of the arcuate cutting edge  22  of the saw blade  12 . Thus, preferably, movement of the depth control guide  16  in a direction (upwardly as viewed in  FIG. 3 ) that increases the distance D between the arcuate depth control surface  30  and the arcuate cutting edge  22  results in some degree of elastic deformation of the depth control guide  16 , as the depth control guide  16  is flexed to decrease the radius of curvature R 2  of the arcuate depth control surface  30 . This elastic deformation results in a restoring force that resists further movement of the depth control guide  16  in that direction. The resistance against further upward movement helps to maintain the relative positions of the depth control guide  16  and blade  12  when the arcuate depth control surface  30  is subjected to external normal forces due to its abutting engagement with the work piece being cut.  
      Preferably, the saw blade  12  is of a ferromagnetic material (e.g. steel) and the depth control guide  16  includes at least one magnet  50  for connecting the depth control guide  16  to the saw blade  12 . More preferably, the depth control guide  16  includes a plurality of such magnets  50  and the depth control guide  16  is connected to the saw blade  12  only via the magnets  50 . As shown in  FIG. 3 , the depth control guide  16  preferably includes a plurality of enlarged portions or bosses  52  to which the magnets are permanently affixed, such as with a suitable adhesive or other appropriate bond.  
      In the preferred embodiment of the invention, the magnets comprise rare earth magnets (e.g., Alnico, Neodymium or Samarian Cobalt). Rare earth magnets are preferred because of their significant magnetic strength relative to their size and weight. However, other types of magnetic materials or non-magnetic fasteners could be used without departing from the scope of the invention as claimed hereinafter. Preferably, the magnets  50  are of sufficient strength to resist movement of the depth control guide  16  relative to the arcuate cutting edge  22  of the saw blade  12  when the depth control guide  16  is subjected to external normal forces exerted on the arcuate depth control surface  30  by a surface of material being cut during a normal cutting operation. This, coupled with the internal restoring forces of the depth control guide  16  caused by the elastic deformation of the depth control guide  16 , will preferably be sufficient to prevent unwanted movement of the depth control guide  16  relative to the arcuate cutting edge  22  during a normal cutting operation.  
      As best shown in the exploded view of  FIG. 2 , the saw blade  12  preferably includes a plurality of slots  60 , each of the slots  60  corresponding to one of the magnets  50 . Each slot has a lower end  62  generally adjacent the arcuate cutting edge  22  of the blade and an upper end  64  that is spaced from the arcuate cutting edge  22  of the blade  12 . As shown in  FIG. 5 , each of the magnets  50  preferably includes a projection  66  that is dimensioned to engage its corresponding slot  60  in a manner to permit sliding movement of the magnet  60  relative to the blade  12  along the slot  60  in a manner to permit adjustment of the position of depth control guide  16  relative to the arcuate cutting edge  22  of the saw blade  12  to achieve the desired cutting depth. Thus, adjustment of the position of depth control guide  16  relative to the arcuate cutting edge  22  of the saw blade  12  can be accomplished without tools.  
      Preferably, the slots  60  are located along the saw blade  12  in a generally symmetrical manner and the magnets  50  are located along the depth control guide  16  in a correspondingly generally symmetrical manner (i.e., the magnets are positioned along the depth control guide  16  in a manner so that the spacings between the magnets is generally even) so that the depth control guide  16  may be used on either side of the saw blade  12 . This will allow the blade  12  to be used for a flush cutting operation on either side.  
      As best shown in  FIGS. 2 and 3 , the slots  60  are not parallel with one another. Instead, the slots  60  are preferably oriented relative to one another so that the spacing between the lower ends  62  of the slots  60  is greater than the spacing of the upper ends  64  of the slots  64 . This forces flexion of the depth control guide  16  in a plane parallel to the blade  12  as the depth control guide  16  is moved away from the arcuate cutting edge  22  to increase cutting depth. The radius of curvature R 2  of the arcuate depth control surface  30  decreases as the magnets  50  slide along their respective slots  60  during movement of the depth control guide  16  away from the arcuate cutting edge  22  (upwardly as viewed in  FIG. 3 ) to increase cutting depth. As discussed above, this reduction in the radius of curvature R 2  of the arcuate depth control surface  30  serves to maintain a generally constant spacing between the arcuate depth control surface  30  and the arcuate cutting edge  22  of the saw blade  12  along the length of the arcuate cutting edge  22 , and thereby ensures that the arcuate depth control surface  30  and the arcuate cutting edge  22  of the blade  12  will remain substantially concentric.  
      Preferably, the slots  60  are oriented at an angle relative to the arcuate cutting edge  22  so that external normal forces exerted on the depth control guide  16  by the work piece during cutting are not acting parallel to the slot. Ideally, the slots  60  are oriented at an angle that will result in the external normal forces acting in a direction that is generally perpendicular to the slots  60 . The orientation of the slots  60  shown in the Figures is intended for blade teeth that are set to cut on a pull stroke. As the saw blade  12  is pulled (generally to the right as viewed in  FIG. 3 ), external normal forces exerted on the depth control guide  16  will be acting in a direction that is generally upwardly and to the left (as viewed in  FIG. 3 ). In the case of a saw blade that is designed for blade teeth that are set to cut on a push stroke, the slots  60  may be oriented in the opposite direction. As shown in  FIG. 3 , for each slot  60 , an imaginary line T 1  that is tangent to and intersecting with the arcuate cutting edge  22  at a point adjacent the lower end  62  of the slot  60  forms an acute angle α with the slot  60 . Preferably, this angle is between about 30 and 60 degrees, though other angles or slot orientations could be used without departing from the scope of the invention as claimed hereinafter.  
      Thus, in the preferred embodiment of the invention shown in the Figures, the strength of the magnets  50 , the internal restoring forces caused by the elastic deformation of the depth control guide  16 , and the angled orientation of the slots  60 , will together resist unwanted movement of the depth control guide  16  relative to the arcuate cutting edge  22  during a normal cutting operation.  
      In an alternative embodiment of the invention shown in  FIG. 7 , slots are replaced by a series of holes  80 . Each of these holes  80  is preferably dimensioned to receive the projection  66  of one of the magnets  50 . Preferably, the holes  80  are located in substantially the same positions as the slots  60  or the previously described embodiment. Thus, adjustment of the position of depth control guide  16  relative to the arcuate cutting edge  22  of the saw blade  12  to achieve the desired cutting depth is accomplished by engaging the magnets  50  with selected holes  80 .  
      While the present invention has been described by reference to specific embodiments and specific uses, it should be understood that other configurations and arrangements could be constructed, and different uses could be made, without departing from the scope of the invention as set forth in the following claims.