Patent Publication Number: US-2006005681-A1

Title: Blade guard assembly for saws

Description:
REFERENCE TO CROSS-RELATED APPLICATION  
      The present application derives priority under 35 USC 119(e) from U.S. Patent Application No. 60/586,039, filed Jul. 7, 2004. 
    
    
     FIELD OF THE INVENTION  
      This invention relates generally to a blade guard assembly for saws and more specifically to a blade guard assembly for a combination table/miter saw.  
     BACKGROUND OF THE INVENTION  
      It is well known in the miter saw field to provide a blade guard assembly to cover a blade when the saw assembly is in an upper position. Typically such blade guard assembly is moved when the saw assembly is moved downwardly towards a workpiece. Such blade guard assembly is not typically used on table saws or combination table/miter saws. It is an object of the invention to provide an enhanced blade guard assembly for combination table/miter saws, and miter saws.  
     SUMMARY OF THE INVENTION  
      In accordance with the present invention, an improved support assembly is employed. The power tool has a base assembly, a table supported by the base assembly, a saw assembly pivotally attached to the table via a trunnion, the saw assembly including a motor, a blade driven by the motor, an upper blade guard covering an upper part of the blade, a lower blade guard pivotally attached to the upper blade guard for covering a lower part of the blade, an auxiliary blade guard pivotally attached to the lower blade guard, a link attached at one end to the trunnion and at the other end to the lower blade guard, an auxiliary link attached at one end to the link and at the other end to the auxiliary blade guard, and an uplock assembly comprising a guard lock movable between a first position contacting the lower blade guard and a second position not contacting the lower blade guard.  
      Additional features and benefits of the present invention are described, and will be apparent from, the accompanying drawings and the detailed description below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings illustrate preferred embodiments of the invention according to the practical application of the principles thereof, and in which:  
       FIG. 1  illustrates a combination table/miter saw according to the invention, whereas  FIGS. 1A-1B  are side views of the combination table/miter saw in the miter saw and table saw modes, respectively;  
       FIG. 2  illustrates the saw assembly with a blade guard assembly according to the invention, where  FIGS. 2A-2B  are left and right side views of such blade guard assembly, respectively; and  
       FIG. 3  is a perspective view of a dust collector according to the invention. 
    
    
     DETAILED DESCRIPTION  
      The invention is now described with reference to the accompanying figures, wherein like numerals designate like parts. Referring to  FIG. 1 , a combination table/miter saw  100  may include a base assembly  10 , a table  11  supported by base assembly  10 , and a saw assembly  20  supported by the table  11 . Saw assembly  20  may include a trunnion  21  disposed on the table  11 , a pivotable arm  22  pivotably attached to trunnion  21 , a motor  24  supported by the arm  22  and driving a blade  23 . Arm  22  also supports upper blade guard  27 , which covers an upper part of blade  23 . Lower blade guard  25  is pivotally attached to upper blade guard  27 . An auxiliary blade guard  26  may be pivotably connected to lower blade guard  25 .  
      Preferably, table  11  is pivotally attached to base assembly  10  via joint  15  so that, when the table  11  is in the orientation of  FIG. 1A , the saw assembly  20  can act as a miter saw, i.e., saw assembly  20  can be pivoted downwardly towards table  11  to cut a workpiece placed on table  11 . The user can use a handle  50  disposed on saw assembly  20  (e.g., on arm  22  and/or upper blade guard  27 ) to pivot saw assembly  20  downwardly towards table  11 .  
      On the other hand, when table  11  is rotated via joint  15  to the orientation of  FIG. 1B , the saw  100  acts as a table saw, i.e., saw assembly  20  will be supported by and disposed underneath the table  11 . In such orientation, blade  23  extends through the table  11 , so that a user can dispose a workpiece on table  11  and push it towards blade  23  for cutting.  
      Persons skilled in the art will recognize that the invention described below can be applicable to non-combined miter saws.  
      Preferably, base assembly  10  has at least one wheel  13  thereon.  
      Base assembly  10  may also support four leg assemblies  30 . Preferably leg assemblies  30  are pivotally attached to base assembly  10 .  
      Referring to  FIGS. 1-2 , lower blade guard  25  is pivotally connected to upper blade guard  27  at pivot junction  25 P. Auxiliary blade guard  26  is pivotally connected to lower blade guard  25  at pivot junction  26 P.  
      A link  28  is pivotally connected at one end to trunnion  21  and to lower blade guard  25  at the other end. Preferably link  28  is made of metal. It is preferable that link  28  be pivotally connected to lower blade guard  25  at a pivot junction  28 P. Pivot junction  25 P is preferably disposed between the point in trunnion  21  connected to link  28  and pivot junction  28 P. Furthermore, pivot junction  25 P is preferably disposed underneath a line drawn between the point in trunnion  21  connected to link  28  and pivot junction  28 P.  
      With such arrangement, when the saw assembly  20  is moved downwardly towards table  11 , link  28  will pull lower blade guard  25 , exposing blade  23  for the cutting operation.  
      An auxiliary link  29  is pivotally connected at one end to link  28  and to auxiliary blade guard  26  at the other end. Preferably auxiliary link  29  is made of metal. It is preferable that auxiliary link  29  be pivotally connected to auxiliary blade guard  25  at a pivot junction  29 P. Pivot junction  26 P is preferably disposed between the point in auxiliary link  29  connected to link  28  and pivot junction  29 P. Furthermore, pivot junction  26 P is preferably disposed underneath a line drawn between the point in auxiliary link  29  connected to link  28  and pivot junction  29 P.  
      Persons skilled in the art will recognize that it is also preferable that pivot junction  26 P be disposed between pivot junctions  25 P and  29 P. Furthermore, pivot junction  26 P is preferably disposed underneath a line drawn between the pivot junctions  25 P and  29 P.  
      Similarly, pivot junction  28 P is preferably disposed between the point in auxiliary link  29  connected to link  28  and pivot junction  29 P. Furthermore, pivot junction  28 P is preferably disposed underneath a line drawn between the point in auxiliary link  29  connected to link  28  and pivot junction  29 P.  
      With such arrangement, auxiliary blade guard  26  will move as lower blade guard  25  is rotating to expose the blade  23 .  
      Preferably lower blade guard  25  moves over upper blade guard  27  and underneath auxiliary blade guard  26  when rotating.  
      Having such blade guard assembly covers more periphery of the blade  23  when the saw assembly  20  is in the upper position, while exposing more periphery of blade  23  (thus increasing cutting capacity) when the saw assembly  20  is in the lower position.  
      A handle  35  may be rotatably attached to link  28 . A pull link  36  may be pivotally attached to handle  35  at one end and to auxiliary link  29  at the other end. With such arrangement, the user can rotate handle  35  to lift auxiliary blade guard  26  and/or lower blade guard  25 .  
      This is especially useful when saw  100  is being used in table saw mode, as lower blade guard  25  and/or auxiliary blade guard  26  may be contacting the underside of table  11 . Lower blade guard  25  and/or auxiliary blade guard  26  may prevent saw assembly  20  from beveling. The user can reach underneath table  11 , pull handle  35 , lifting auxiliary blade guard  26  and/or lower blade guard  25 , allowing the saw assembly  20  to bevel.  
      Referring to  FIG. 2B , an uplock assembly  40  may be provided on upper blade guard  27  to prevent saw assembly  20  from pivoting downwardly towards table  11  when saw  100  is being used in miter saw mode. Uplock assembly  40  may include a lever  41  disposed near handle  50  and pivotably connected to upper blade guard  27 , a guard lock  43  pivotably attached to upper blade guard  27  and rotatable between a first position engaging lower blade guard  25  and a second position not engaging lower blade guard  25 , and a link  42  connected to lever  41  at one end and to guard lock  43  at the other end.  
      With such arrangement, the user would need to rotate lever  41  towards handle  50 , causing guard lock  43  to rotate towards the second position, i.e., away from lower blade guard  25 , allowing lower blade guard  43  to rotate and thus allowing saw assembly  20  to rotate downwardly. If the user does not rotate lever  41  as described above, guard lock  43  will engage lower blade guard  25 , not allowing lower blade guard  25  to rotate and not allowing saw assembly  20  to rotate downwardly.  
      Persons skilled in the art will recognize that guard lock  43  may be designed to engage auxiliary blade guard  26  instead of or in addition to lower blade guard  25 , and yet achieve the same result, i.e., not allowing saw assembly  20  to rotate downwardly until guard lock  43  is moved to the second position.  
      Persons skilled in the art will also recognize that a spring (not shown) should be provided to bias guard lock  43  towards the first position. Similarly, a spring (not shown) can be provided to lever  41  to bias it away from handle  50 .  
      Because lower blade guard  25  typically does not contact arm  22 , a rear guard is typically provided between arm  22  and lower blade guard  25  to cover the periphery of blade  23  therebetween. Dust duct assembly  60  is preferably provided on arm  22  to replace the typical rear guard.  
      Referring to  FIGS. 1-3 , dust duct assembly  60  may have two walls  61  substantially parallel to blade  23 . These walls  61  are connected to a dust duct  63 . Persons skilled in the art will recognize that walls  61  preferably define a chamber therebetween that is connected to a dust exhaust channel within dust duct  63 . Preferably part of the periphery of blade  23  extends into such chamber.  
      Each wall  61  may have a secondary wall  62  extending towards blade  23 . Secondary walls  62  may act as blade calipers, limiting the sideways motion of blade  23 . Alternatively, secondary walls  62  may contact the body of blade  23  before the blade&#39;s teeth contact upper blade guard  27 , lower blade guard  25  and/or auxialiary blade guard  26 . Persons skilled in the art will recognize secondary walls will not necessarily lower the amount of dust received by the chamber (and/or by dust duct  63 ) as the blade periphery is preferably disposed between the dust duct  63  and the secondary walls  62 .  
      Dust duct  63  may extend past and/or through arm  22 , and may be connected to a hose connected to a vacuum source, or to an elbow  64  for redirecting the flow of dust moving through dust duct  63 . Preferably dust duct  63  extends past, rather than through, arm  22 . In this manner dust duct  63  does not interfere with the spring (not shown) biasing arm  22  (and saw assembly  20 ) to the upper position.  
      It is preferable to provide walls  65  pivotably attached to dust duct  63 . Alternatively walls  65  may be pivotably attached to walls  61 . Preferably a wall  65  is disposed adjacent to a wall  61  and/or on each side of dust duct  63 . Both walls  65  may be connected via a boss  65 B. Boss  65 B may travel along an arcuate slot  61 S disposed on both walls  61 .  
      With such arrangement, movable walls  65  can pivot from a lower position to an upper position. Preferably, at least one spring  67  biases walls  65  towards the lower position. Walls  65  can pivot upwardly when lower blade guard  25  is in the original position contacting walls  65  (see  FIG. 2A ). Walls  65  can also pivot upwardly when one wall  65  contacts a fence  16  during a beveling operation.  
      A resilient flap  66  may be connected to dust duct  63 . Preferably flap  66  is disposed underneath walls  61  and  65  to provide a bottom wall to the chamber defined by walls  61 .  
      Persons skilled in the art will recognize that dust duct  63  and/or walls  61  may be attached to arm  22 .  
      Persons skilled in the art may recognize other additions or alternatives to the means disclosed herein. However, all these additions and/or alterations are considered to be equivalents of the present invention.