Abstract:
A saw assembly includes a base defining an internal space, and having a sidewall defining an opening, a table top structure supported by said base and defining a blade slot, a support arrangement including (i) a first rail assembly attached to said base and having a first rail magnet, (ii) a carriage located within said internal space and having a first carriage magnet that is positioned to magnetically interact with said first rail magnet, a saw mechanism supported by said carriage and including a motor and a saw blade rotatably coupled to said motor, said saw blade extending through said blade slot, and an actuator having (i) a first end portion attached to said carriage, (ii) a second end portion spaced apart from said internal space, and (iii) an intermediate portion extending through said opening, wherein movement of said second end portion of said actuator causes movement of said carriage in relation to said first rail assembly.

Description:
FIELD 
       [0001]    The present invention relates generally to power tools and more particularly to a pull-push table saw. 
       BACKGROUND 
       [0002]    A table saw can be used for cutting a workpiece, e.g., a board. The table saw includes a saw unit that includes a circular blade that is coupled to a saw motor. Two types of table saws are known. In the first known type, the saw unit is stationary and an operator of the table saw slides the workpiece toward the circular blade to cut the workpiece, followed by pulling the workpiece away from the circular blade after the workpiece is cut. In the second known type (a pull-push table saw), the workpiece is stationary and the operator pulls the saw unit toward the workpiece to cut the workpiece, followed by pushing the saw unit away from the workpiece once the workpiece is cut. A typical construction in the latter type of table saw includes an undercarriage that is configured to slide on a rail system for the purpose of pulling, and then pushing the saw unit. The undercarriage is typically spring-loaded and is biased to return to a home position away from the workpiece. To reduce friction between the undercarriage and the rail system, provisions have been provided in the known pull-push table saws. Among these provisions are rollers and bearing surfaces that interface the undercarriage with the rail system. However, the roller-bearing provision may be susceptible to malfunctioning, e.g., sticking, when debris, produced during a cutting operation, is introduced between the rollers and the bearing surface. 
         [0003]    Therefore, there is a need to provide an improved interface between the undercarriage of a table saw and the rail system. There is further a need to provide a low friction or essentially frictionless interface between the undercarriage of a table saw and an associated rail system. There is yet an additional need to provide an interface between the undercarriage of a table saw and the associated rail system that is less susceptible to malfunctioning due to debris produced during a cutting operation. 
       SUMMARY 
       [0004]    According to one embodiment of the present disclosure, a saw assembly is disclosed. The saw assembly includes a base, a support arrangement which includes (i) a first rail assembly attached to said base and having a first rail magnet, (ii) a carriage having a first carriage magnet that is positioned to magnetically interact with said first rail magnet, and a saw mechanism supported by said carriage. 
         [0005]    According to another embodiment of the present disclosure a saw assembly is disclosed. The saw assembly includes a base defining an internal space, and having a sidewall defining an opening, a table top structure supported by said base and defining a blade slot, a support arrangement including (i) a first rail assembly attached to said base and having a first rail magnet, (ii) a carriage located within said internal space and having a first carriage magnet that is positioned to magnetically interact with said first rail magnet, a saw mechanism supported by said carriage and including a motor and a saw blade rotatably coupled to said motor, said saw blade extending through said blade slot, and an actuator having (i) a first end portion attached to said carriage, (ii) a second end portion spaced apart from said internal space, and (iii) an intermediate portion extending through said opening, wherein movement of said second end portion of said actuator causes movement of said carriage in relation to said first rail assembly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The above described features and advantages, as well as others, will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings. 
           [0007]      FIG. 1  depicts a perspective schematic view of a push-pull table saw of the present disclosure with its table top removed for clarity of description; 
           [0008]      FIG. 2  depicts a perspective schematic view of a table top of the push-pull table saw of  FIG. 1  with a circular saw blade passing through a slot defined in the table top; 
           [0009]      FIG. 3  depicts a fragmentary top schematic view of the push-pull table saw of  FIG. 1 ; 
           [0010]      FIG. 4  depicts a cross sectional view of a magnetic support interface of the push-pull table saw of  FIG. 3 ; and 
           [0011]      FIG. 5  depicts an enlarged fragmentary view of the portion of  FIG. 4  that is encircled and labeled as “FIG.  5 .” 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    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. 
         [0013]      FIG. 1  depicts a sliding table saw  10  of the push-pull type. The sliding table saw  10  includes side support walls  12 ,  14 ,  18 , and  20 , a front support wall  16 , a rear support wall  22 , rails  104  and  106 , rail brackets  24 ,  26 ,  28 , and  30 , and a slide rod  32 . The sliding table saw  10  also includes a magnetic slide system  100 , which includes a saw mechanism  36  having a motor  38  and a saw blade  40 . The sliding table saw  10  also includes a table top  50 , shown in  FIG. 2 , configured to support a workpiece W. The table top  50  centrally includes a slot  52  for the saw blade  40  to pass through the slot  52  to cut or shape the workpiece W that is supported on the table top  50 . The slide rod  32  is connected to the magnetic slide system  100 . A handle  34  is connected to one end of the slide rod  32 . 
         [0014]    The combination of side, front and rear support walls  12 ,  14 ,  16 ,  18 ,  20 , and  22  provide a structural frame for the sliding table saw  10 , and particularly for the table top  50 . The table top  50  fastens to a top surface of the side, front and rear support walls  12 ,  14 ,  16 ,  18 ,  20 , and  22 . Rails  104  and  106  are received by rail brackets  24 ,  26 ,  28 , and  30  to support the rails  104  and  106 . The rail brackets ( 24 ,  26 ,  28 , and  30 ) support the rails  102  and  104 , and the rails  104  and  106  support the magnetic slide system  100 . Also, while rail brackets  24 ,  26 ,  28 , and  30  are depicted in  FIG. 1 , it should be appreciated that other interfaces for coupling the rails  104  and  106  to the front and back support walls  16  and  22  may be implemented. 
         [0015]      FIG. 3  depicts the magnetic slide system  100  in more detail. The magnetic slide system  100  includes the undercarriage  102 , top connecting members  108 ,  110 , and  112 , top magnetic support members  114 ,  116 , and  118 , and the saw mechanism  36 . The undercarriage  102  is connected to the top connecting members  108 ,  110 , and  112 . The top connecting members  108 ,  110 , and  112  are connected to the top magnetic support members  114 ,  116 , and  118 , respectively. The connecting members  108 ,  110 , and  112  are configured to provide minimal horizontal deflection under the weight of the undercarriage  102  and the saw mechanism  36 . The saw mechanism  36  is mounted to the undercarriage  102  by fasteners (not shown). 
         [0016]    While two rails  104  and  106  are depicted in  FIG. 3 , it should be appreciated that a variety of other configurations are also possible. For example, a single rail below the undercarriage  102  may provide appropriate support and stability for the undercarriage  102  and the saw mechanism  36 . 
         [0017]    The magnetic slide system  100  and the rails  104  and  106 , define three (3) magnetic support interfaces  200 , as shown in  FIG. 3 . A cross sectional view of a magnetic support interface  200  about the line identified as AA in  FIG. 3  is depicted in  FIG. 4 . The magnetic support interface  200  is defined by the top connecting member  108 , a bottom connecting member  109 , the top magnetic support member  114 , a bottom magnetic support member  115 , and a brace  202 . The top connecting member  108  is connected to the top magnetic support member  114  by fasteners, not shown, or by spot welding. Alternatively, the top connecting member  108  and the top magnetic support member  114  may be integrally formed as one piece. The bottom connecting member  109  is connected to the bottom magnetic support member  115  by fasteners, not shown, or by spot welding. Alternatively, the bottom connecting member  109  and the bottom magnetic support member  115  may be integrally formed as one piece. The top connecting member  108  is connected to the bottom connecting member  109  by the brace  202 . The connection between the top and bottom connecting members  108  and  109  and the brace  202  is formed by fasteners, not shown, or spot welding. Alternatively, the top connecting member  108 , the bottom connecting member  109 , and the brace  202  may be integrally formed as one piece. While the brace  202  is depicted as the connecting member between the top and bottom connecting members  108  and  109 , it should be appreciated that the bottom connecting member may alternatively extend and connect to the undercarriage  102  directly. 
         [0018]      FIG. 5  depicts further details of the magnetic support interface  200 . The magnetic support interface  200  is further defined by a first magnetic strip  204 , a second magnetic strip  206 , a third magnetic strip  208 , and a fourth magnetic strip  210 . The first magnetic strip  204  is connected to a bottom surface of the top magnetic support member  114 . The second magnetic strip  206  is connected to a top surface of the rail  104 . The third magnetic strip  208  is connected to a bottom surface of the rail  104 . The fourth magnetic strip  210  is connected to a top surface of the bottom support member  115 . The first and the second magnetic strips  204  and  206  are positioned to magnetically interact with each other. Similarly, the third and fourth magnetic strips  208  and  210  are positioned to magnetically interact with each other. Each of the first, second, third, and fourth magnetic strips  204 ,  206 ,  208 , and  210  has a first pole spanning one longitudinal face of the strip and a second pole spanning the second longitudinal face of the strip. The first and second magnetic strips  204  and  206  have the same pole facing toward each other. In particular, the longitudinal faces of the first and second magnetic strip  204  and  206  that face each other have an “S” pole. The longitudinal faces of the first and second magnetic strips  204  and  206  that face the top magnetic support member  114  and the rail  104 , respectively, have the opposite pole, i.e., the “N” pole. Similarly, the third and fourth magnetic strips  208  and  210  have the same pole pointing toward each other. Specifically, the longitudinal faces of the third and fourth magnetic strips  208  and  210  that face each other have the “S” pole. The longitudinal faces of the third and fourth magnetic strip  208  and  210  that face the rail and the bottom magnetic support member  114 , respectively, have the opposite pole, i.e., the “N” pole. The orientation of the poles of the first, second, third, and fourth magnetic strips  204 ,  206 ,  208 , and  210  are depicted in  FIG. 5  in the cutouts shown in the top and bottom magnetic support members  114  and  115 . 
         [0019]    Since the longitudinal faces of the first and second magnetic strips  204  and  206  that face each other have the same pole, these strips generate a magnetic field that tends to push the first and second magnetic strips  204  and  206  apart from each other. Therefore, the interface between the first and second magnetic strips  204  and  206 , and the weight of the undercarriage  102  and other components coupled thereto, generates a net repulsion force which results in an air gap, shown in  FIG. 5  as BB. Therefore, the undercarriage  102  and other components coupled thereto levitate above the rails  104  and  106 . While calculating the repulsive force between the first and second magnetic strips  204  and  206  is a complex mathematical operation that depends on the shape, magnetization, orientation and separation of the first and second magnetic strip  204  and  206 , it is known in the art that the force between two magnetic poles is inversely proportional to the distance between the two poles. Therefore, the repulsion force generated between the first and the second magnetic strips  204  and  206  is inversely proportional to the distance between these strips, i.e., the air gap BB. 
         [0020]    Similarly, since the longitudinal faces of the third and fourth magnetic strips  208  and  210  that face each other have the same pole, these strips oppose each other and thereby generate a magnetic field that tends to push the third and fourth magnetic strips  208  and  210  apart from each other to generate an air gap CC. The repulsion force between the third and fourth magnetic strips  208  and  210  is in an opposite direction than the repulsion force of the first and second magnetic strips  204  and  206 . Therefore, the weight of the undercarriage and the components coupled thereto, and the repulsion force between the third and fourth magnetic strips  208  and  210  cooperate to oppose the repulsion force generate by the interface between the first and second magnetic strips  204  and  206 . Also, upward forces generated during a cutting operations of the saw mechanism  36  on the workpiece W, cooperate with the repulsion force generated by the interface between the first and second magnetic strips  204  and  206  to oppose the repulsion force generated by the magnetic interaction between the third and fourth magnetic strips  208  and  210 . These repulsion forces, the weight of the undercarriage and components coupled thereto as well as the upward forces generated during the cutting operation cause the top and bottom magnetic support members  114  and  115  to levitate above the rail  104  to provide a vertically stable sliding system. 
         [0021]    Although the above described forces are in a vertical direction, because of the geometric configuration of the top and bottom magnetic support members  114  and  115  and the rail  104 , the repulsion force generated between the first and second magnetic strips  204  and  206 , and between the third and fourth magnetic strips  208  and  210  have components that lie in both a horizontal direction, X axis shown in  FIG. 5 , and in the vertical direction, Z axis shown in  FIG. 5 . While, the vertical components of the forces generate vertical stability for the magnetic support interface, the horizontal components of the forces generate horizontal stability. In particular, the shape of the rails  104  and  106  and the top and bottom magnetic support members  114  and  115 , generate a tight horizontal structural interface that minimizes undesirable side to side movement of the undercarriage  102  and other components coupled thereto. 
       Operation of the Sliding Table Saw 
       [0022]    An operator of the sliding table saw  10  places the workpiece W on the table top  50  which is supported by the side, front and rear support walls  12 ,  14 ,  16 ,  18 ,  20 , and  22 . The operator raises the saw blade  40  through the slot  52  of the table top  50  in a manner known in the art, e.g., by using a cam and rollers, to an appropriate height for cutting the workpiece W. Similarly, the operator tilts the saw blade  40  to an appropriate bevel angle, in a manner known in the art. The operator grips the handle  34  and slides the undercarriage  102  of the magnetic slide system  100  toward and away from the workpiece W. The magnetic interactions between the magnetic strips  204 ,  206 ,  208 , and  210  result in a smooth sliding action of the undercarriage  102  and the saw mechanism  36  mounted thereto. 
         [0023]    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.