Patent Abstract:
A rail system for a power tool has a base defining a work surface for supporting a workpiece, a support mounted to the base, a number of elongated rails slidably supported by the support for movement relative thereto, a yoke engaged to the number of elongated rails for movement with the elongated rails, and a power tool assembly supported by a yoke for performing an operation on the workpiece. A rail stop is movably mounted to one of the support and the yoke, the rail stop including a stop surface adapted to abut the other of the support and the yoke when the rail stop is in a first position between the yoke and the support. The rail stop is movable to a second position different from the first position.

Full Description:
REFERENCE TO RELATED APPLICATION AND PRIORITY CLAIM 
       [0001]    This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application No. 61/776,932 filed Mar. 12, 2013, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    The present application present disclosure concerns power tools in which the working tool travels on rails, such as a sliding miter saw, and in particular to modifications to the rail components to accommodate large workpieces. 
       BACKGROUND 
       [0003]    Many power tools include a working tool slidably supported on rails so that the tool can traverse a workpiece, such as the sliding miter power saw  10  shown in  FIGS. 1(   a )-( b ). The power saw includes a saw assembly  12  connected by a yoke  24  to a rail system  20 . The rails are slidably supported by a structure, such as a bevel post  22 , mounted on a base or platform  14 . The saw assembly may be supported on the yoke to be pivoted downward toward the workpiece. The rails  20  allow the saw assembly to be precisely positioned relative to the platform  14 , and particularly the workpiece, to make a chop cut for instance. In other procedures, the saw assembly can travel along the rails during to perform a slide cut. 
         [0004]    One detriment of current miter saws arises when performing mitered cuts on large workpieces, such as the crown molding C or large base board B shown in  FIGS. 1(   a ),  1 ( b ). The height of the workpiece above the platform  14  challenges the cutting capacity of the typical miter saw because the workpiece interferes with the components of the saw assembly  12 . In order to accommodate such large workpieces it is necessary to position the saw blade  13  between the fully extended or fully retracted extremes on the rails, but not at the extremes. Such precise positioning is very difficult to achieve and unforgiving should the rails slide away from the optimal location during the cut. 
         [0005]    What is needed is a modified rail system that allows the operator to precisely stop and hold the saw blade assembly at the optimum location for making cuts in large workpieces. 
       SUMMARY 
       [0006]    A rail system for a power tool has a base defining a work surface for supporting a workpiece, a support mounted to the base, a number of elongated rails slidably supported by the support for movement relative thereto, a yoke engaged to the number of elongated rails for movement with the elongated rails, and a power tool assembly supported by a yoke for performing an operation on the workpiece. In one aspect of the present disclosure, a rail stop is movably mounted to one of the support and the yoke, the rail stop including a stop surface adapted to abut the other of the support and the yoke when the rail stop is in a first position between the yoke and the support. The rail stop is movable to a second position different from the first position. 
         [0007]    In one feature, the rail stop is an elongated plate that extends parallel to the elongated rails that includes an end portion disposed generally perpendicular to the elongated rails to define the stop surface. In certain embodiments the rail stop is pivotably mounted to pivot between a first position in which the stop surface abuts the other of the support and the yoke and a second position in which the stop surface is no longer between the support and the yoke. In other embodiments, the elongated plate defines a slot along the length of the plate and the one of the support and the yoke includes a pin projecting therefrom into the slot. In one aspect, the slot includes a notch at one end, corresponding to the first position of the rail stop, in which the notch receives the pin to hold the rail stop in the first position abutting the other of the support and the yoke. 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0008]      FIGS. 1(   a ), ( b ) are perspective views of a sliding miter saw with examples of large workpieces in position for a cut. 
           [0009]      FIGS. 2(   a )-( d ) are views of a rail stop incorporated into a sliding miter saw, such as the saw of  FIGS. 1(   a )-( b ), with the rail stop shown in deployed and retracted positions. 
           [0010]      FIG. 3  is an enlarged perspective view of a rail stop plate according to one aspect of the present disclosure. 
           [0011]      FIGS. 4(   a )-( b ) are views of an alternative rail stop incorporated into a sliding miter saw, such as the saw of  FIGS. 1(   a )-( b ), with the rail stop shown in deployed and retracted positions. 
           [0012]      FIGS. 5(   a )-( c ) are views of another rail stop incorporated into a sliding miter saw, such as the saw of  FIGS. 1(   a )-( b ), with the rail stop shown in deployed and retracted positions. 
           [0013]      FIGS. 6(   a )-( b ) are views of yet another rail stop incorporated into a sliding miter saw, such as the saw of  FIGS. 1(   a )-( b ), with the rail stop shown in deployed and retracted positions. 
           [0014]      FIG. 7  is an enlarged perspective view of a rail stop plate according to a further aspect of the present disclosure. 
           [0015]      FIG. 8  is a side view of a rail stop similar to the rail stop of  FIGS. 6(   a )-( b ) but slidably with the rails top plate, as shown in  FIG. 7 , mounted to the yoke of the power tool. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one skilled in the art to which this invention pertains. 
         [0017]    The above-described problem of making cuts on large workpieces is addressed by incorporating a selectable rail stop into the rail system  20 . In one embodiment, a rail stop  30  is mounted to the bevel post  22  at a pivot mount  32 , as shown in  FIGS. 2(   a )-( d ). The rail stop  30  may be in the form of an elongated plate  31  that terminates in a right angle end portion  34  that defines a stop surface adapted to abut the yoke  24  of the miter saw. The rail stop is pivotably mounted at the pivot mount  32  to pivot in a vertical plane relative to the base between a first position in which the end portion  34  is disposed between the yoke and the bevel post and a second position in which the end portion is no longer between the two components. The end portion  34  may define a cut-out  35  configured to extend around a portion of a rail of the rail system  20 , as illustrated in  FIGS. 2(   b ),  3 , so that the stop surface of the end portion can be at least partially aligned with the line of travel of the rails system. 
         [0018]    The rail stop plate  30  is sized so that the movement of the saw assembly  12  and rail assembly  20  toward the bevel post  22  is limited to a pre-determined distance between the bevel post and yoke. As seen in comparing  FIG. 2(   a ) with  FIG. 2(   c ), the deployed rail stop  30  holds the saw assembly at a distance  36  ( FIG. 2(   a )) from the bevel post  22 . This distance is calibrated so that the structure of the saw assembly does not interfere with a large workpiece, such as the workpieces shown in  FIGS. 1(   a )-( b ). It can be appreciated that the rail stop  30  operates as a stop rather than as a lock so that the rail stop may be deployed prior to movement of the saw assembly  12 . With the rail stop deployed, the operator can advance the saw assembly and rail assembly  20  along the bevel post  22  without fear that the saw assembly will interfere with the workpiece on the platform  14 . Thus, the operator can perform a slide cut on the large workpiece. If a chop cut is to be performed, the moment applied to the saw assembly to make the cut will keep the yoke  24  pressed against the rail stop  30 . When the rail stop is not required it can be retracted to the position shown in  FIGS. 2(   c )-( d ). 
         [0019]    Other embodiments of the rail stop are contemplated as illustrated in  FIGS. 4-5 . The rail stop  40  shown in  FIGS. 4(   a )-( b ) is mounted to the yoke  24  at a pivot mount  42 , rather than to the bevel post as in the previous embodiment. The rail stop  40  includes the same right angle end portion  44  that is configured to abut the bevel post  22  instead of the yoke as in the previous embodiment. The rail stop  40  is otherwise similar in structure and operation to the rail stop  30 . 
         [0020]    A rail stop  50  shown in  FIGS. 5(   a )-( c ) is mounted to the bevel post at a pivot mount  52  that is situated on the top of the bevel post  22 , rather than on the side of the bevel post as in the first disclosed embodiment, so that the rail stop pivots in a horizontal plane relative to the base. Like the stops  30  and  40 , the rail stop  50  includes a right angle end portion  54  that abuts the yoke  24  to limit the travel of the slide rail assembly  20  and saw assembly  12  in the same manner as the prior embodiments. 
         [0021]    In a further embodiment, a rail stop  60  shown in  FIGS. 6(   a )-( b ) is in the form of a flat plate  62  terminating in a right angle end portion  61  defining a stop surface similar to the end portions described above. However, rather than pivoting between deployed and retracted positions, the rail stop  60  slides or translates relative to the bevel post  22 . The rail stop  60  includes a slot  64  extending along the length of the stop, terminating at its opposite ends in notches  65  and  66 , as shown in the detail view of  FIG. 7 . The notches are configured to receive a pin  70  projecting from the side of the bevel post  22 . In a deployed first position shown in  FIG. 6(   a ) the pin  70  is disposed in the notch  66  so that the end portion  61  abuts the yoke  24  at a pre-defined first distance from the bevel post  22 . When the rail stop  60  is in its retracted second position shown in  FIG. 6(   b ) the pin  70  is disposed in the notch  65  at the opposite end of the stop. In the second position the end portion  61  is at a second distance from the bevel post that is less than the first distance. In a specific embodiment, in the second position the end portion  61  is immediately adjacent the bevel post. It can be appreciated that in the second position the end portion may still abut the yoke  24  when the rail system is at one end of movement, but the second distance in this position is generally simply the thickness of the plate  62 . 
         [0022]    In a further embodiment, a rail stop  80 , shown in  FIG. 8 , is similar to the rail stop  60  depicted in  FIGS. 6   a ,  7  except that the rail stop is mounted to the yoke rather than to the bevel post. The rail stop  80  is in the form of a flat plate terminating in a right angle end portion  85  that abuts the bevel post and including a slot  82  extending along the length of the stop, terminating at its opposite ends in notches  83 ,  84  similar to the notches in  FIG. 7 . A pin  86  projects from the side of the yoke to engage the slot  82 , instead of projecting from the side of the bevel post as in the prior embodiment. In the deployed position shown in  FIG. 8 , the pin is disposed in the notch  83  farthest from the bevel post. In the retracted position (not shown), the pin  86  is situated in the notch  84  that is nearest the bevel post, so that the rail stop  80  does not interfere with the rails moving directly against the bevel post, as shown in  FIG. 6(   b ). 
         [0023]    It is contemplated that the rail stops  60 ,  80  may include only one notch, namely notch  66  and  86 , to hold the rail stop in its extended first position ( FIGS. 6(   a ),  8 ). It is further contemplated that the slots  64 ,  82  may define intermediate notches between the ends of the slot. The intermediate notches would receive the post in the same manner as the notches  65 ,  66 ,  83 ,  84  but would operate to hold the rail stop at different intermediate distances as desired by the tool operator. 
         [0024]    The rail stops  30 ,  40 ,  50 ,  60  and  80  may be formed of a rigid material capable of withstanding pressure when the saw is used to make a chop cut, or impact when the saw is used to make a slide cut. Preferably the rail stops are formed of a metal, such as stainless steel. The rail stops may incorporate a dampening material, such as a thin foam layer to provide some damping when the stop is contacted during a slide cut. The configuration of the rail stops and their respective pivot or slide mounts may be modified according to the structure of the power tool. For instance, while the illustrated embodiments the end portions project at a right angle relative to elongated plate portion of the rail stop, the end portions may project at a non-perpendicular angle provided that the stop surface can solidly abut the yoke or bevel post during a cut. 
         [0025]    It can be appreciated that the rail stops disclosed herein may be readily retrofit to an existing power tool. For instance, the pivot mount  32  for the rail stop  30  of  FIGS. 2(   a )-( d ) may be engaged to the bevel post  22  by a screw. Similarly, the pin  70  of the embodiment shown in  FIG. 6(   a )-( b ) may also be a screw threaded into the bevel post, with the head of the screw holding the rail stop  60  in position relative to the bevel post. 
         [0026]    The present disclosure provides a rail stop for a slide miter saw or similar power tool in which the rail stop is movable from a retracted position in which the saw assembly and rail assembly are free to move to their full extent, to an extended position in which the movement of the saw and rail assemblies is limited to a predetermined position that provides clearance for large workpieces. The rail stop thus allows a conventional miter saw to be used to make cuts in crown molding, large base boards and the like. 
         [0027]    While the invention has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the invention are desired to be protected.

Technology Classification (CPC): 1