Patent Abstract:
A miter saw has a base assembly, a table assembly rotatably disposed on the base assembly, a support housing connected to the table assembly, and a saw assembly pivotably attached to the support housing. The saw assembly is pivotable downwardly for cutting a workpiece disposed on the table assembly. The saw has a miter lock assembly including a shoe assembly connected to the table housing and movable between a first position not contacting the base assembly and a second position contacting the base assembly. The shoe assembly has a movable shoe for adjusting the angular position of the table assembly relative to the base assembly.

Full Description:
REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. application Ser. No. 11/846,165, filed on Aug. 27, 2007, now pending, which in turn derives priority from U.S. Application No. 60/823,969, filed on Aug. 30, 2006. All the teachings of U.S. application Ser. Nos. 11/846,165 and 60/823,969 are hereby incorporated by reference. 
    
    
     FIELD 
     This specification relates to miter saws and more specifically to a miter saw having a fine adjustment mechanism for miter cuts. 
     BACKGROUND 
     Referring to  FIG. 1 , a miter saw typically has a base assembly  10 , a table assembly  20  rotatably attached to the base assembly  10 , a support housing  30  connected to the table assembly  20 , and a saw assembly  40  pivotally connected to the support housing  30 . The saw assembly  40  may include an arm  41  pivotally connected to support housing  30 , an upper blade guard  42  connected to arm  41 , a motor (not shown) supported by arm  41  and/or upper blade guard  42 , a blade  43  driven by the motor, and a lower blade guard  44  pivotally attached to the upper blade guard. 
     A fence assembly  15  is typically attached to base assembly  10 . With such construction, a user can place a work piece against fence assembly  15  and table assembly  20  for cutting. The user can make a miter cut by rotating table assembly  20  relative to base assembly  10 . 
     If support housing  30  is pivotally attached to table assembly  20 , the user can rotate support housing  30  relative to table assembly  20  and/or base assembly  10 , tilting the blade  43  relative to the table assembly  20 , thus changing the blade&#39;s bevel angle. A cut made with the blade  43  tilted at an angle (and perpendicular to the fence assembly  15 ) is known as a “bevel cut.” A cut made with the blade  43  set to both an angle relative to the fence assembly  15  (miter angle) and an angle relative to the base assembly  10  (bevel angle) is known as a “compound cut.” 
     Miter saws typically include a detent system  12  that allows the table assembly  20  and the blade  43  to be preset to specific angles relative to the fence assembly  15 . A detent system  12  provides an accurate means to preset and reset the saw to make the most popular cuts. Such detent system  12  may include a detent plate  13  with detent recesses formed thereon. Alternatively, the detent recesses may be formed on base assembly  10 . Such recesses can receive a spring-biased detent, fixing the position of table assembly  20  relative to the fence assembly  15 . Persons skilled in the art are directed to US Published Application No. 2005/0284276, which is hereby fully incorporated by reference, for further information on such detent systems, operation thereof, and miter lock mechanisms. 
     If a user wants to preset the miter saw for an angle cut not provided by the detent system, the user would allow the spring-loaded detent to rest against the detent plate  13  and/or the base assembly  10  outside of the detent recesses and engage the miter lock mechanism. Due to the interaction between the spring-loaded detent and the detent recesses, however, the prior art arrangements do not allow for a fine adjustment that is near one of the predetermined detent positions. 
     Some solutions have been proposed to solve this problem. US Published Application No. 2004/0154448, for example, discloses a mechanism for adjusting the position of the detent engaging the recesses. However, such mechanism is difficult to adjust and to reset to the original position. 
     Similarly, US Published Application Nos. 2005/0284276, 2005/0262984 and 2006/0016310 disclose rack-and-pinion and/or worm drive mechanisms for adjusting the position of the table assembly relative to the base assembly. However such mechanisms are difficult to reset to the original position. 
     SUMMARY 
     A miter saw comprising a base assembly, a table assembly rotatably disposed on the base assembly, a support housing connected to the table assembly, a saw assembly pivotably attached to the support housing, the saw assembly being pivotable downwardly for cutting a workpiece disposed on the table assembly, a miter lock assembly including a pivotable shoe assembly connected to the table housing and movable between a first position not contacting the base assembly and a second position contacting the base assembly, the shoe assembly comprising a movable shoe for adjusting the angular position of the table assembly relative to the base assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings illustrate preferred embodiments according to the practical application of the principles thereof, and in which: 
         FIG. 1  illustrates a prior art miter saw. 
         FIG. 2  is a partial perspective view of a miter saw according to the invention. 
         FIG. 3  is a partial perspective view of the miter saw of  FIG. 2 . 
         FIG. 4  is a partial top plan view of a shoe assembly according to the invention. 
         FIG. 5  is a cross-sectional view along line V-V of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention will now be described more fully hereinafter. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
     Referring first to  FIGS. 1-4 , base assembly  10  preferably supports a detent plate  13  with detent recesses  13 R. Table assembly  20  preferably carries a miter lock assembly  50 , a miter detent mechanism  60 , and a fine adjust mechanism  70 . 
     Miter lock assembly  50  preferably includes miter lock handle  51  pivotally attached to table assembly  20  and a miter lock shaft  52 . Miter lock shaft  52  is preferably connected to miter lock handle  51  so that it moves towards base assembly  10  when miter lock handle  51  is rotated downwardly. 
     A cam or eccentric  51 C may be disposed on miter lock handle  51  to contact and push miter lock shaft  52  towards the base assembly  10 . Persons skilled in the art will recognize that eccentric  51 C may be replaced with other mechanisms that can convert the rotational motion of miter lock handle  51  into a linear motion for miter lock shaft  52 . 
     Miter lock shaft  52  preferably pushes a shoe assembly  53  towards base assembly  10 . Shoe assembly  53  preferably includes a housing  53 H pivotally attached to table assembly  20  via pivot  53 P. 
     A shoe  53 S may be slidably disposed within housing  53 H. Shoe  53 S may have knurling or other textures thereon to enhance the friction contact between shoe  53 S and base assembly  10 . Shoe  53 S may have a slot  53 SS that receives a retainer  53 R attached to housing  53 H. Bolts  53 B may connect retainer  53 R to housing  53 H. 
     A spring  54  may be disposed between table assembly  20  and housing  53 H to bias housing  53 H (and thus shoe assembly  53 ) away from base assembly  10 . 
     The operation of miter lock assembly  50  will be discussed below. 
     The miter detent mechanism  60  preferably includes a detent member  63  which is pivotally attached to table assembly  20 . Detent member  63  preferably carries a detent  63 D that engages a recess  13 R. A spring  64  may be disposed between detent member  63  and table assembly  20  to bias detent member  63  towards detent plate  13  (and thus biasing detent  63 D towards recess  13 R). Persons skilled in the art will recognize that detent member  63  may be made of spring metal, thus combining the functions of detent member  63  and spring  64 . 
     Detent member  63  (and thus detent  63 D) may be lifted away from detent plate  13  and recess  13 R via a lever  62  which is preferably pivotally attached to table assembly  20 . Lever  62  may have a button  61  which extends beyond the table assembly  20 , allowing the user to push downwardly button  61 , causing detent member  63  (and thus detent  63 D) to be lifted away from detent plate  13  and recess  13 R. 
     Referring to  FIG. 5 , button  61  and/or lever  62  may have a tongue  61 T extending therefrom. Tongue  61 T may be disposed underneath miter lock handle  51 . 
     The operation of miter detent assembly  60  will be discussed below. 
     Referring to  FIGS. 2-4 , the fine adjust mechanism  70  preferably includes a fine adjust knob  71 , a fine adjust shaft  72  attached to fine adjust knob  71 , and a pinion assembly  73 . 
     Pinion assembly  73  may have at one end a pinion  73 P meshing with a rack  53 SR disposed on shoe  53 S. At the other end, pinion assembly  73  may have a hex ball  73 B. Fine adjust shaft  72  preferably has a hex socket  72 H disposed at one end to engage hex ball  73 B. Such connection creates a hex ball joint, which preferably allows axial movement between pinion assembly  73  and fine adjust shaft  72 , while allowing variance in the angle created between pinion assembly  73  and fine adjust shaft  72 . 
     A spring  73  may be attached to table assembly  20  and fine adjust shaft  72 . Spring  73  may bias fine adjust shaft  72  towards a “neutral” rotational position. Accordingly, when the fine adjust shaft  72  is rotated in either direction, spring  73  may be wound or unwound, creating such bias, so that when the torque on fine adjust shaft  72  is released, the spring  73  returns fine adjust shaft  72  to the original neutral position. 
     With such construction, a user can adjust the miter angle as follows: the user pushes button  61 , rotating lever  62  and lifting detent member  63  (and thus detent  63 D) off detent plate  13 , allowing the user to rotate table assembly  20  relative to base assembly  10 . When the desired miter angle is obtained, the user releases button  61 , allowing detent member  63  (and thus detent  63 D) to contact detent plate  13  and possibly engage recess  13 R. 
     The user then locks the miter angle by rotating miter lock handle  51  downwardly. As miter lock handle  51  is rotated, miter lock shaft  52  pushes housing  53 H towards base assembly  10 , so that shoe  53 S contacts base assembly  10 , fixing the miter angle. Persons skilled in the art will recognize that the friction developed between shoe  53 S and housing  53 H will preferably fix the angular position of the table assembly  20  relative to the base assembly  10 . In addition, as miter lock handle  51  is rotated, tongue  61 T causes lever  62  to rotate, lifting detent member  63  (and thus detent  63 D) off detent plate  13 . In other words, the detent  63 D is disengaged when the miter lock assembly  50  is engaged. 
     Persons skilled in the art will note that it is preferably that the shoe  53 S comes into contact with table assembly  20  before tongue  61 T comes into contact with miter lock handle  51 . In this manner, the table assembly  20  will be partially locked, and thus held in place, before the detent  53 D is lifted out of the detent recess  13 R. 
     If the user wants to finely adjust the miter angle without disengaging miter lock assembly  50  and readjusting the miter angle, the user can rotate the fine adjust knob  71 , which causes the fine adjust shaft  72  and pinion assembly  73  to rotate. Persons skilled in the art will recognize that the user must supply enough torque to overcome the friction force developed between shoe  53 S and housing  53 H. As pinion assembly  73  rotates, the pinion  73 P meshing with rack  53 SR causes shoe  53 S to move sideways, causing table assembly  20  to move relative to base assembly  10 , without disengaging shoe  53 S (and thus shoe assembly  53 ) from base assembly  10 . 
     When the user wants to change the miter angle, the user can rotate miter lock handle  51  upwards, moving miter lock shaft  52  away from base assembly  10 , allowing spring  54  to rotate shoe assembly  53  away from base assembly  10 . Persons skilled in the art will recognize that, when shoe assembly  53  is rotated away from base assembly  10 , shoe  53 S does not contact base assembly  10 . Such persons should also recognize that, because shoe  53 S does not contact base assembly  10 , rotating fine adjust knob  71  will not affect the miter angle. Persons skilled in the art should also recognize that, when the user unlocks miter lock handle  51 , and shoe  53 S does not contact base assembly  10 , spring  73  can cause fine adjust shaft  72  to rotate and return to the original neutral position. 
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.

Technology Classification (CPC): 8