Abstract:
A compound miter saw includes a unique table assembly which incorporates an orientation system for a group of wear plates and a three position lock system. The wear plates between the table assembly and the base of the miter saw have a different configuration at each end which requires them to be assembled into the table saw with any burred edge being positioned away from the table assembly. The lock system incorporated into the table assembly is movable between three positions. The first position locks the table to the miter saw. The second position permits rotation of the table with a spring loaded detent system releasably locking the table at various miter angles. The third position permits rotation of the table with the spring loaded detent system being disengaged providing free movement of the table.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. application Ser. No. 08/761,035, filed Dec. 5, 1996 now U.S. Pat. No. 6,474,206, which claims benefit of Provisional Application No. 60/008,516, filed Dec. 12, 1995. 

   FIELD OF THE INVENTION 
   The present invention relates to compound miter saws or other power operated equipment or machinery utilizing a cutter for performing working operations on a workpiece. More particularly, the present invention relates to improvements in the table assembly for the miter adjustment for such power operated equipment. The table assembly includes a three position locking mechanism and a set of orientated wear plates. 
   BACKGROUND OF THE INVENTION 
   Saws and other apparatuses designed for cutting or performing other working operations on a workpiece typically require adjustment mechanisms for moving the saw blade or cutting tool into an angular relationship to the workpiece. Examples of such equipment include cross-cut compound miter saws which are adapted for allowing the user to selectively move the saw blade into any of a number of positions or modes for square cutting, miter cutting, bevel cutting, or compound miter cutting where a combination miter and bevel are cut. In addition, some operations, such as dado cutting or shaping operations, for example, require the use of saw blades or other cutting or working devices of different shapes or sizes to be substituted for one another in order to perform the desired operation on the workpiece, whether the workpiece is composed of wood, plastic, metal other materials. 
   In order to allow for the adjustment in miter and bevel angles, the saw blade, cutter or other working device is angularly adjustable with respect to a horizontal base and a vertical fence against which the workpiece is positioned. The miter adjustment allows the saw blade, cutter or other working device to move angularly with respect to the vertical fence while maintaining perpendicularity with the horizontal base. The bevel adjustment allows the saw blade, cutter or other working device to move angularly with respect to the horizontal base while maintaining perpendicularity with the vertical fence. At times it may be desirable to cut a combination miter and bevel by simultaneously adjusting the angularity of the blade with respect to both the horizontal base and the vertical fence. 
   Once the saw blade, cutter or other working device has been adjusted to the desired position with respect to the horizontal base and the vertical fence, locking mechanisms for the miter and bevel adjustment must be activated in order to prohibit movement of the saw blade, cutter or other working device with respect to the base and fence while the cutting operation is preformed. These locking mechanisms need to be easily activated, adjustable and quick acting in order to optimize the efficiency of the cutting apparatus and provide convenience to the operator of the apparatus. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, an improved table assembly incorporating a miter locking mechanism is employed. The locking mechanism includes an axially extending rod which has a three positional lever assembly at one end and a rod spring at the opposite end. The rod spring is utilized to engage a series of detents arranged at the various popular miter angles as well as locking the table at the desired miter angle. The lever assembly is movable between a first position where the miter table is locked at a specified position, a second position where the miter table is releasably held by the detents at one of the various popular miter angles and a third position where the detents are by-passed, thus allowing for adjustment of the table to a position in between miter detents. In addition to the improved miter locking mechanism, the present invention includes a unique set of wear plates disposed between the table assembly and its supporting base. The wear plates incorporate features which ensure their correct orientation during assembly of the miter saw. 
   Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings which illustrate the best mode presently contemplated for carrying out the present invention: 
       FIG. 1  is a front perspective view of a sliding compound miter saw in accordance with the present invention; 
       FIG. 2  is a front elevational view of the sliding compound miter saw shown in  FIG. 1 ; 
       FIG. 3  is a rear elevational view of the sliding compound miter saw shown in  FIGS. 1 and 2 ; 
       FIG. 4  is a side elevational view of the sliding compound miter saw shown in  FIGS. 1 through 3 ; 
       FIG. 5  is an assembled perspective view, partially in cross-section of the table assembly shown in  FIGS. 1 through 4 ; 
       FIG. 6  is an exploded perspective view of the miter locking mechanism in accordance with the present invention; 
       FIG. 7  is a plan view of the miter saw base illustrating the fool-proof assembly of the wear plates in accordance with the present invention; and 
       FIGS. 8A–8C  are cross-sectional side views of the miter locking mechanism in accordance with the present invention showing the mechanism in its various positions. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is shown in  FIGS. 1 through 4  an exemplary sliding compound miter saw incorporating a table assembly in accordance with the present invention, shown merely for the purposes of illustration, and designated generally by the reference numeral  10 . One skilled in the art will readily recognize from the following description, taken in conjunction with the accompanying drawings and claims, that the principles of the present invention are equally applicable to sliding compound miter saws, compound miter saws, chop saws, radial arm saws, table saws or other saws of types other than that shown for purposes of illustration in the drawings. Similarly, one skilled in the art will readily recognize that the principles of the table assembly according to the present invention are also applicable to other types of powered or unpowered equipment for performing an operation on a workpiece. Such equipment includes, but is not limited to, dado saws, spindle shapers or sanders, or other types of powered or unpowered devices that would benefit from the table assembly of the present invention. 
   Referring primarily to  FIGS. 1 through 4 , sliding compound miter saw  10  comprises a base assembly  12 , a table assembly  14 , a housing assembly  16 , a saw blade  18 , a blade guard  20 , a motor  22  drivingly connected to saw blade  18 , a handle  24  and a fence assembly  26 . Table assembly  14  is secured to base assembly  12  such that it can be rotated in order to provide adjustment for miter cutting. The rotation of table assembly  14  changes the angle of saw blade  18  relative to fence assembly  26  but maintains the perpendicularity of saw blade  18  with table assembly  14 . A locking mechanism  28  can be activated in order to lock table assembly  14  to base assembly  12 . 
   Housing assembly  16  is secured to table assembly  14  such that it can be pivoted with respect to table assembly  14  in order to provide adjustment for bevel cutting. As can be appreciated by one skilled in the art, the adjustments for mitering and beveling can be separate or they can be adjusted simultaneously in order to provide a compound miter and bevel cut. The pivoting of housing assembly  16  changes the angle of saw blade  18  relative to table assembly  14  but maintains the perpendicularity of saw blade  18  with fence assembly  26 . A locking mechanism  30  can be activated in order to lock housing assembly  16  to table assembly  14 . 
   Referring to  FIG. 5 , the present invention is directed towards table assembly  14  and locking mechanism  28  which locks table assembly  14  to base assembly  12  at any specified miter angle. Base assembly  12  defines a circular mounting structure  40  which includes a cylindrical cup shaped mounting boss  42  for mounting a table  44  as will be described later herein. Base assembly  12  also defines a plurality of threaded apertures  46  which are used to mount a detent plate  48  using a plurality of bolts  50 , only one being shown in  FIG. 5 . Detent plate  48  defines a plurality of slots  52  which correspond to the plurality of threaded apertures  46  in order to allow for the securing of detent plate  48  to base assembly  12  by bolts  50 . The plurality of slots  52  permit adjustment of detent plate  48  to ensure the proper relationship of the pre-specified miter angles. Detent plate  48  further defines a plurality of detents  54  which are located at various popular miter angles for saw  10 . Detents  54  work in conjunction with locking mechanism  28  to locate table  44  at one of the various popular miter angles as will be described later herein. 
   Table assembly  14  includes table  44  and locking mechanism  28 . Table  44  is a circular plate-like member defining a work supporting surface  56  and a mounting boss  58 . Table  44  is rotatably mounted to base assembly  12  by inserting boss  58  of table  44  into boss  42  of base assembly  12 . A bolt  60  is inserted through table  44  and threadably received within a threaded bore  62  ( FIG. 7 ) in base assembly  12  to complete the assembly. Bolt  60  is tightened enough to secure table  44  to base assembly  12  but it is not tightened to the point of restricting rotation of table  44  with respect to base assembly  12 . The threads on bolt  60  incorporate a patch lock to lock bolt  60  in position once it has been tightened. 
   Table  44  rotates with respect to base assembly  12  in order to change the miter angle of saw  10 . This rotation of table  44  changes the angular relationship of saw blade  18  with respect to fence assembly  26  but does not change the angular relationship of saw blade  18  with respect to table  44 . Disposed between table  44  and base assembly  12  are a plurality of wear plates  64 . Wear plates  64  provide a surface to support table  44  as well as reducing the friction and wear between table  44  and base assembly  12 . Wear plates  64  are preferably manufactured from spring steel and protect base assembly  12  which is preferably manufactured from aluminum from excessive wear that would cause excessive play between base assembly  12  and table  44  leading to cutting inaccuracy. 
   Referring now to  FIG. 7 , wear plates  64  are preferably manufactured from pre-hardened steel using a stamping operation. This stamping of wear plates  64  forms a burred edge on one side of wear plates  64  which needs to be positioned against the stationary base  12  such that these burred edges do not interfere with the fit or rotation of table  44 . In order to ensure proper orientation of wear plates  64 , they are each provided with a first end  66  being cut along a radial line or perpendicular to a tangent line at that point and a second end  68  being cut at an acute angle to a radial line or an acute angle to a tangent line at that point. Base assembly  12  is provided with a plurality of formed shoulders  70  each of which defines a first surface  72  corresponding with first end  66  on plates  64  and a second surface  74  corresponding with second end  68  on plates  64 . Surfaces  66 ,  68 ,  72  and  74  foolproof the assembly of plates  64  to base assembly  12  by allowing only one orientation of each wear plate  64  with respect to base assembly  12  thus ensuring that any forming burr on wear plates  64  is positioned towards base assembly  12  and not towards table  44 . Base assembly  12  includes a circumferentially extending ring  76  which is disposed between adjacent shoulders  70  to support and position wear plates  64 . 
   Referring now to  FIG. 6 , locking mechanism  28  comprises a housing  80 , a locking lever assembly  82 , a threaded locking rod  84  and a locking spring  86 . Housing  80  is generally hollow rectangular member which is fixedly secured to table  44  such that it extends radially outward from table  44 . Housing  80  is positioned on table  44  such that when saw blade  18  is positioned perpendicular to fence assembly  26 , or a 0° miter angle, housing  80  is also generally perpendicular to fence assembly  26 . Thus housing  80  is generally parallel to saw blade  18 . Lever assembly  82  comprises locking lever  87  and detent trigger  89 . Locking lever  87  and detent trigger  89  are pivotably secured to the outside end of housing  80  by a pin  81  and the threaded end of rod  84  is threadingly receiving in a pin  83  which is rotatably secured to detent trigger  89  with rod  84  extending from detent trigger  89  towards table  44 . A coil spring  97  biases detent trigger  89  away from locking lever  87 . Spring  86  is fixedly secured to table  44  by a pair of bolts  88  and defines an aperture  90  which slidingly accepts the opposite end of rod  84 . Spring  86  is a generally U-shaped component with one leg of the U defining a spring detent  92  and the opposite leg of the U defining a locking tab  94 . When spring  86  is assembled to table  44  and table  44  is assembled to base assembly  12 , spring detent  92  is in biased engagement with detent plate  48  to define a detent system between table  44  and base assembly  12  and locking tab  94  is positioned adjacent to a cylindrical surface  96  located on base assembly  12 . In order to increase the load with which spring detent  92  is in biased engagement with detent plate  48 , a washer  91 , a coil spring  93  and a retainer  95  are assembled to rod  84 . Retainer  95  is fixedly secured to rod  84  and spring  93  reacts against washer  91  and thus spring detent  92  to increase the load with which spring detent  92  is biased into engagement with detent plate  48 . 
   Locking mechanism  28  can be located in any one of three positions by the movement of lever assembly  82  as illustrated in  FIGS. 8A–8C . Referring now to  FIG. 8A , locking mechanism  28  is shown in its locked position with locking lever  87  of lever assembly  82  being located at a position approximately 30° down from a horizontal position. In this position, locking lever  87  urges detent trigger  89  downward which urges locking rod  84  towards table  44  which in turn engages locking tab  94  against surface  96  of base assembly  12  locking table  44  in position relative to base assembly  12  at the specific miter angle. The load with which locking rod  84  engages locking tab  94  and surface  96  can be adjusted by rotating locking rod  84  within pin  83  to adjust the working length of rod  84 . A screw driver slot  85  is provided to facilitate this adjustment and a patch lock is incorporated onto the threads of locking rod  84  to retain locking rod  84  in its desired location with respect to pin  83 . 
   Referring now to  FIG. 8B , locking mechanism  28  is shown in its engaged position with locking lever  87  of lever assembly  82  being located at a generally horizontal position. In this position, detent trigger  89  is spaced from locking lever  87  and locking rod  84  is disengaged from locking tab  94 . Table  44  can now be rotated with respect to base assembly  12 . Spring detent  92  is in biased engagement with detent plate  48 , thus rotation of table  44  with respect to base assembly  12  will cause spring detent  92  to ratchet between the plurality of detents  54  to releasably stop at the various popular miter angles for saw  10 . As described above, in order to provide adjustability to saw  10 , detent plate  48  is provided with slots  52  for securing plate  48  to base assembly  12  using bolts  50 . With spring detent  92  being positioned in the “0°” detent, bolts  50  are loosened to allow table  44  to be positioned with respect to base assembly  12  such that saw blade  18  is perpendicular to fence assembly  26 . When the relationship between saw blade  18  and fence assembly  26  has been set, bolts  50  are tightened, securing detent plate  48  and thus table  44  to base assembly  12  in the proper orientation. Movement of table  44  between detents  54  will then cause the accuracy of saw blade  18  in relation to fence assembly  26  to be dictated by the accuracy of the positioning of detents  54  in plate  48 . Because the accuracy of detents  54  and plate  48  are controlled by a stamping operation, the positional relationship of detents  54  on plate  48  can be controlled to tight tolerances thus ensuring the accuracy of saw  10 . While the above adjusting process has been described using the “0°” detent in plate  48 , it is within the scope of the present invention to utilize any of the various detents  54  in plate  48  by checking the appropriate relationship between saw blade  18  and fence assembly  26  if desired. 
   Referring now to  FIG. 8C , locking mechanism  28  is shown in its released position with locking lever  87  of lever assembly  82  being located at the generally horizontal position and detent trigger  89  also being moved to a generally horizontal position. In this position, an annular collar  98 , fixedly secured to rod  84  contacts spring detent  92  and moves it radially outward or away from detents  54 . With spring detent  92  being moved out of engagement with detents  54 , the movement of table  44  with respect to base assembly  12  will occur without spring detent  92  ratcheting between detents  54 . This position of locking mechanism  28  is especially useful when locating table  44  at a miter angle which is not pre-defined by one of detents  54  or when locating table  44  at a miter angle which is close to one of the pre-defined miter angles. When locating table  44  close to one of the pre-defined miter angles, the release of spring detent  92  eliminates the tendency of the system to jump into the adjacent detent thereby making it difficult to set a miter angle close to but not exactly equal to one of the pre-defined miter angles. 
   While the above detailed description describes the preferred embodiment of the present invention, it should be understood that the present invention is susceptible to modification, variation and alteration without deviating from the scope and fair meaning of the subjoined claims.