Abstract:
A table saw fence having a guide rail, a fence beam having a front portion and a rear portion, and a fence face disposed adjacent to the fence beam. The fence face is movable along its longitudinal axis relative to the fence beam. A fence face locking mechanism is provided for locking the fence face relative to the fence beam. The locking mechanism has a handle disposed on the front portion of the fence beam and is movable between a first position where the fence face is locked relative to the fence beam and a second position where the fence is unlocked relative to the fence beam.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This claims the benefit of U.S. Provisional Application No. 61/379,603, filed on Aug. 2, 2010. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a table saw, and more particularly to a table saw having at least one removable fence face. 
       BACKGROUND 
       [0003]    Generally a table saw for cutting work pieces includes a table and a saw assembly.  FIG. 1  depicts a conventional table saw  100 . The table saw  100  includes an alignment system, which includes a rail  108  and a fence beam  104  having a fence face  102 . The alignment system is slidably mounted to the support surface of the table saw  100  via the rail  108 , which extends substantially perpendicular to the saw blade, so that the fence beam  104  is aligned parallel with the saw blade. The alignment system can be locked in place via a handle  114 . The alignment system is used to secure the work piece on top of the table and can be locked in a desired position via the handle  106 . The work piece is rested on top of the table against fence face  102 . 
         [0004]    In conventional table saws, the fence face  102  may be damaged as a result of frequent contact with the edges of the work piece. Also, depending on the type of work piece used, different types of fence faces (e.g., sacrificial fence faces, stop blocks for miter cuts, and other dedicated faces custom-made by the user) may be desirable. What is needed is an alignment system with a replaceable fence face. 
         [0005]      FIGS. 2A and 2B  depict a conventional table saw in which the alignment system includes a fence face  202  that is movably and removeably connected to a fence beam  204  via a locking mechanism in the form of fasteners  206 . The end of each fastener  206  is screwed into a face lock  208 , forming a T-shaped clamp fitted inside a grove  210  of the fence face  202 . The fasteners  206  may be tightened to pull the face lock  208  against the fence face  202 , thus securely locking the fence face  202  against the fence beam  204 . Loosening the fasteners  206  releases the face lock  208  inside the groove  210 , thus allowing the fence face  202  to removeably slide parallel to the fence beam  204 . The replaceable face  212  of the fence face  202  may then be easily replaced as needed to meet the user&#39;s specific needs. However, while this arrangement allows the fence face  202  to be removed and replaced, it allows only a single fence face to be used with the fence beam  204 . 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  depicts a conventional table saw having an alignment system. 
           [0007]      FIGS. 2A and 2B  depict a conventional table saw in which the alignment system includes a single fence face that is movably and removeably connected to a fence beam via a set of fasteners. 
           [0008]      FIGS. 3A-3E  depict an alignment system having one or more fence locks, according to an embodiment of the invention. 
           [0009]      FIGS. 4A-4B  depict an alignment system having a lock knob, according to an alternative embodiment of the invention. 
           [0010]      FIGS. 5A and 4B  depict a rear pad arranged under a back portion of the fence beam, according to another aspect of the invention. 
       
    
    
     DESCRIPTION 
       [0011]      FIGS. 3A-3E  depict an alignment system  300  according to an embodiment of the invention. The alignment system  300  includes two fence faces  302  and a fence beam  304 . The alignment system  300  is slidably mounted to the support surface of the table saw via the guide rail  308 , so that the fence beam  304  is aligned parallel with a saw blade arranged on the saw table. The alignment system can be locked in place via a handle  314 , as is well known in the art. 
         [0012]    As shown in  FIG. 3A , the fence beam  304  includes two locking mechanisms. Each locking mechanism includes a face lock  306  located on an upper or front surface of the fence beam  304 . Each fence face  302  includes a T-shaped groove  310  facing the fence beam  302 . As described in detail below, pushing the face lock  306  down into a locked position (as depicted) forces a T-shaped clamp of the locking mechanism to engage an inner surface of the groove  310 , thus locking the fence face  302  against the fence beam  304 . Lifting the face lock  306  to an unlocked position will disengage the T-shaped clamp of the locking mechanism from the groove  310  and allow the fence face  302  to slide out of its position parallel to fence beam  304 . The locking mechanisms operate independently. Thus, one of the fence faces  302  may be unlocked and replaced while the other is still locked to the fence beam  304 . 
         [0013]      FIG. 3B  depicts the locking mechanism according to an embodiment of the invention. The locking mechanism includes a beam plate  324  attached to the face lock  306  via a link  322 . The beam plate  324  is alideably disposed within the fence beam  304 . Inside the beam plate  324  is a cavity  325 , within which a roller plate  318  is fixed to the beam plate  324 . The roller plate  318  itself includes an aperture  320 . 
         [0014]    As shown in  FIGS. 3C and 3D , the locking mechanism includes a T-shaped clamp  321 . The T-shaped clamp  321  includes a lock plate  316  arranged to engage the groove  310  of the fence face  302  on one end. The other end of the T-shaped clamp  321  is connected to at least one roller  326  through the aperture  320  to engage the back portion of the roller plate  318 . The roller plate  318  includes a curved portion  319  curved towards the lock plate  316 . In the unlocked position, the rollers  326  engage the curved portion of the roller plate  318 , which loosens the lock plate  316  of the T-shaped clamp  321  inside the groove  310  of the fence face  302  (see  FIG. 3A ). This allows the fence face  302  to traverse freely parallel to the fence beam  304 . Conversely, as the face lock  306  is pushed down to the locked position, the link  322  moves the beam plate  324  and the roller plate  318  relative to the lock plate  316 . As the roller plate  318  is moved, the rollers  326  is forced to roll behind the uncurved portion of the roller plate  318 , forcing the lock plate  316  of the T-shaped clamp  321  to come in contact with and press against an inner wall of the groove  310  of the fence face  302 . The traction between the lock plate  316  and the inner wall of the groove  310  securely locks the fence face  302  against the fence beam  304 . 
         [0015]      FIG. 3E  shows another view of the locking mechanism according to the above-described embodiment. As can be seen, the fence face  302  engages the fence beam  305  via a hook  330 . The hook  330  limits the outward movement of the fence face  302  in the unlocked position. Accordingly, the fence face  302  can securely slide out in parallel to the fence beam  304  without wobbling. 
         [0016]    Although the above-described embodiment discloses two fence faces  302 , it will be understood by persons of ordinary skill in the art that the alignment system of the invention can be made using a single fence face  302 . Also a single lock mechanism can be utilized to lock and/or unlock both fence faces  302 . Furthermore, although a single curved portion of the roller plate  318  is depicted along with a single set of rollers  326  and a single T-shaped clamp, embodiments of the invention may be utilized using two or more curved portions engaging two or more sets of rollers  326  and two or more T-shaped clamps. Similarly, a single lock plate  316  may extend though the length of the fence face  302  or multiple lock plate  316  may be utilized. 
         [0017]      FIGS. 4A and 4B  depict a locking mechanism according to an alternative embodiment of the invention. In this embodiment, as in the previous embodiment described with reference to  FIGS. 3A-3E , the alignment system  400  includes a fence beam  404  and two fence faces  402 . Also, a handle  414  is used to lock the alignment system  400  over the table saw having a rail  408 . Instead of using fence locks and roller plates to lock the fence faces  402  described above, this embodiment utilizes a lock knob  432  arranged on a front face of the fence beam  404 . Turning the lock knob  432  in one direction (e.g., clockwise) causes the T-shaped clamp  421  to press against an inner wall of the groove  410 , thus locking the fence beam  404  against the fence face  402 . Turning the lock knob  432  in the opposite direction (e.g., counter-clockwise) releases the T-shaped clamp  421  inside the groove  410 , allowing the fence face  402  to slide out of position parallel to the fence beam  404 . 
         [0018]    As shown in  FIG. 4B , the lock knob  432  is connected via a shaft  444  to one or more threaded regions  442 . In the exemplary embodiment of  FIG. 4B , the adjacent threaded regions  442  include oppositely-arranged threads, although the threaded regions may include threads in the same direction. A follower nut  440   a ,  440   b  is fastened on each threaded region  442 . Each follower nuts  440   a ,  440   b  is attached on two ends to two links  446  of the T-shaped clamps  421 . The links  446  are attached to a lock face  448  of the T-shaped clamp  421  at fixed positions. 
         [0019]    Turning the lock knob  432  clockwise causes the threaded regions  442  to turn via the shaft  444 . As the threaded regions  442  turn, the upper follower nuts  440   a ,  440   b  traverse in the longitudinal direction away from their original (unlocked) position. In this example, since the threaded regions  442  include oppositely-arranged threads, the follower nut  440   a  traverses away from the lock knob  432  and the lower follower nut  440   b  traversed towards the lock knob  432 . As the follower nuts  440   a ,  440   b  move away from their original (unlocked) position, the acute angle α between the links  446  and the lock faces  448  becomes smaller, thus pulling the lock faces  448  closer towards the shaft  444 . The lock faces  448  of the T-shaped clamps  421  thus press against the inner walls of the grooves  410  of the fence faces  402 , locking the fence faces  402  against the fence beam  404 . 
         [0020]    In contrast, as the lock knob  432  is turned counter-clockwise, the follower nuts  440   a ,  440   b  move back to their unlocked position, the angle α becomes larger, and the lock faces  448  are pushed further away from the shaft  444 . The lock faces  448  are thus loosened inside the groove  410 , allowing the fence faces  402  to slidably move relative to the fence beam  404 . 
         [0021]    Another aspect of the invention is discussed herein with reference to  FIGS. 5A and 5B . Generally, the top surface of table saws may include some unevenness, which would result in a gap between an end portion of the fence beam and the surface of the table. This gap may cause the end portion of the fence beam to become unstable. To overcome this problem, as shown in  FIGS. 5A and 5B , a rear pad  506  is provided under the fence beam  504 . The ends of the rear pad  506  are arch-shaped to fit inside cavities  512  of the fence beam  504 . A middle portion of the rear pad  506  includes a projection  514  that fits inside a gap  516  between two protrusions  518  of the fence beam  504 . The rear pad  506  additionally includes a number of set screws  508  used to adjust a height of the fence beam  504  relative to the end pad  504 . Thus, the height of the rear pad may be adjusted depending on the size of the gap  503  between the end portion of the fence beam  504  and the table  510 . 
         [0022]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the scope of the invention.