Abstract:
A table saw includes a worktable, a left extension frame and a right extension frame respectively slidably mounted at left and right sides of the worktable, a scale unit including a first scale, a second scale and a third scale respectively mounted at the worktable, the left extension frame and the right extension frame, and an indicator unit including a first indicator, a second indicator and a third indicator respectively disposed to aim at the first, second and third scales. Thus, when operating the table saw to cut a workpiece, the user can selectively pull out the left or right extension frame and use the corresponding scale and indicator for quickly judging the correctness of the length to be cut.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0001]    The present invention relates to table saw technology and more particularly, to table saw that is equipped with a scale system for quickly marking the cutting length. 
       2. Description of the Related Art 
       [0002]    On a table saw of conventional technology, a scale is provided at the edge of the worktable so that the operator can use the scale to control the cutting length of the workpiece. Further, for cutting a large size workpiece, an extension frame is provided at one side of the worktable. When the extension is pulled out, it can be used with the worktable together to support a large size workpiece for cutting. 
         [0003]    In order for allowing the operator to read the cutting length of a large size workpiece after the extension frame is pulled out, Taiwan Patent M270864, issued to the present inventor, teaches the use of an automatic rewind tape measure in a rear guide rail of the extension frame. When the operator pulls out the extension frame, the automatic rewind tape measure is synchronously extended out. At this time, the operator can use a scale indicator to read the graduations on the automatic rewind tape measure. However, in this prior art design, the position of the automatic rewind tape measure is not easy for the operator to accurately read the readings, so the effect of practical application is not ideal. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a table saw, which allows selective use of different scales and indicators at different locations for quickly marking the cutting length when cutting a different size of workpiece. 
         [0005]    To achieve this and other objects of the present invention, a table saw comprises a worktable, a left extension frame, a right extension frame, a scale unit and an indicator unit. The worktable comprises a first fixed rail and a second fixed rail respectively located at the opposing front and rear sides thereof. The left extension frame comprises a first left movable rail, a second left movable rail and a left support platform. The first and second left movable rails are respectively slidably mounted in the first and second fixed rails of the worktable. The left support platform is connected to one end of each of the first and second left movable rails, and movable with the first and second left movable rails toward or away from the left side of the worktable. The first and second right movable rails are respectively slidably mounted in the first and second fixed rails of the worktable. The right support platform is connected to one end of each of the first and second right movable rails, and movable with the first and second right movable rails toward or away from the right side of the worktable. The scale unit comprises a first scale, a second scale and a third scale. The first scale is located at the first fixed rail of the worktable. The second scale is located at the first left movable rail of the left extension frame. The third scale is located at the first right movable rail of the right extension frame. The indicator unit comprises a first indicator, a second indicator and a third indicator. The first indicator is located at one end of the first right movable rail of the right extension frame remote from the right support platform and aimed at the first scale. The second indicator is located at the front side of the worktable and aimed at the second scale. The third indicator is detachably mounted at the first right movable rail of the right extension frame and aimed at the third scale. 
         [0006]    Thus, when the left and right extension frames are not extended out, the user can use the third scale and the third indicator to measure the cutting length of the workpiece. When pulled out the left extension frame, the user can use the second scale and the second indicator to measure the cutting length of the workpiece. When pulled out the right extension frame, the user can use the first scale and the first indicator to measure the cutting length of the workpiece. In other words, when cutting a different size of workpiece, the user can achieve the effect of quickly marking the cutting length by selectively using the scales and indicators at the three different locations. 
         [0007]    Other advantages and features of the present invention will be fully understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference signs denote like components of structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is an oblique top elevational view of a table saw in accordance with the present invention, illustrating left and right extension frames in a received status. 
           [0009]      FIG. 2  corresponds to  FIG. 1 , illustrating the left extension frame pulled out of the worktable. 
           [0010]      FIG. 3  corresponds to  FIG. 1 , illustrating the right extension frame pulled out of the worktable. 
           [0011]      FIG. 4  is an enlarged view of a part of the present invention, illustrating the relative positioning relationship between the first, second and third scales of the table saw 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0012]    Referring to  FIG. 1 , a table saw  10  in accordance with the present invention is shown. The table saw  10  comprises a base  20 , a worktable  30 , a cutting mechanism  40 , a left extension frame  50 , a right extension frame  60 , a rip fence  70 , a scale unit  80 , and an indicator unit  90 . 
         [0013]    The base  20  is adapted for positioning on the floor. 
         [0014]    The worktable  30  is mounted on a top wall of the base  20  for supporting a workpiece. The worktable  30  defines a front side  31 , a rear side  32 , a left side  33  and a right side  34 . As illustrated in  FIG. 2 , a first fixed rail  35  and a second fixed rail  36  are respectively mounted at the front side  31  and the rear side  32 . Further, the worktable  30  has a cutting slot  37  on the middle. 
         [0015]    The cutting mechanism  40  comprises power drive (not shown), a cutter blade  41  and a cutter blade guard  42 . The power drive is mounted in the base  20 . The cutter blade  41  is connected to the power drive and inserted through the cutting slot  37  of the worktable  30  so that the cutter blade  41  can be driven by the power drive to cut a workpiece. The cutter blade guard  42  surrounds a part of the cutter blade  41  and is disposed above the worktable  30  to prevent the surrounding person from accidentally touching the cutter blade  41  and being injured. 
         [0016]    As illustrated in  FIGS. 1, 2 and 4 , the left extension frame  50  comprises a first left movable rail  52 , a second left movable rail  52  and a left support platform  53 . The first and second left movable rails  51 , 52  are respectively slidably mounted in the first and second fixed rails  35 , 36  of the worktable  30 . The left support platform  53  is connected to one end of each of the first and second left movable rails  51 , 52  so that the left support platform  53  is movable with the first and second left movable rails  51 , 52  toward or away from the left side  33  of the worktable  30 . 
         [0017]    As illustrated in  FIGS. 1, 2 and 4 , the right extension frame  60  comprises a first right movable rail  61 , a second right movable rail  62  and a right support platform  63 . The first and second right movable rails  61 , 62  are respectively and partially slidably mounted in the first and second fixed rails  35 , 36  of the worktable  30  and respectively and partially slidably mounted in the first and second left movable rails  51 , 52 . The right support platform  63  is connected one end of each of the first and second right movable rails  61 , 62  so that the right support platform  63  is movable with the first and second right movable rails  61 , 62  toward or away from the right side  34  of the worktable  30 . 
         [0018]    The rip fence  70  is detachably and selectively mounted at the worktable  30 , the left support platform  53  of the left extension frame  50  or the right support platform  63  of the right extension frame  60 , and adapted for supporting one end of the workpiece to be cut to enhance cutting stability. 
         [0019]    Referring to  FIG. 4  again, the scale unit  80  comprises a first scale  81 , a second scale  82  and a third scale  83 . The first scale  81  is mounted on the outer surface of the first fixed rail  35  of the worktable  30  between the left side  33  of the worktable  30  and the cutter blade  41 . When the right support platform  63  of the right extension frame  60  is abutted at the right side  34  of the worktable  30 , as illustrated in  FIG. 2 , the first scale  81  is shielded by the first right movable rail  61  of the right extension frame  60 . When the right support platform  63  of the right extension frame  60  is moved far from the right side  34  of the worktable  30 , as illustrated in  FIG. 3 , the first scale  81  is not shielded by the first right movable rail  61  of the right extension frame  60  and can be seen. The second scale  82  is mounted at an outer surface of the first left movable rail  51  of the left extension frame  50 . When the left support platform  53  of the left extension frame  50  is abutted at the left side  33  of the worktable  30 , as illustrated in  FIG. 1 , the second scale  82  is partially shielded by the first right movable rail  61  of the right extension frame  60 . When the left support platform  53  of the left extension frame  50  is moved far from the left side  33  of the worktable  30 , as illustrated in  FIG. 2 , the second scale  82  is not shielded by the first rail movable rail  61  of the right extension frame  60  and can be seen. The third scale  83  is mounted at an outer surface of the first right movable rail  61  of the right extension frame  60 , and constantly exposed to the outside, as illustrated in  FIG. 1 . Further, the graduations of the first scale  81  follow the graduations of the third scale  83 , and the second and third scales  82 ,  83  have the opposite order of graduations. 
         [0020]    The indicator unit  90  comprises a first indicator  91 , a second indicator  92  and a third indicator  93 . The first indicator  91  is located at one end of the first right movable rail  61  of the right extension frame  60  remote from the right support platform  63 , as illustrated in  FIG. 3 , thus, when the right support platform  63  of the right extension frame  60  is disposed far from the right side  34  of the worktable  30 , the first indicator  91  is aimed at the first scale  81 . The second indicator  92  is located in the intersection between the front side  31  and left side  33  of the worktable  30 , as illustrated in  FIG. 3 , thus, when the left support platform  53  of the left extension frame  50  is disposed far from the left side  33  of the worktable  30 , the second indicator  92  is aimed at the second scale  82 . The third indicator  93  is located at one end of the rip fence  70 . When the rip fence  70  is mounted at the worktable  30 , as illustrated in  FIG. 1 , the third indicator  93  is aimed at the third scale  83 ; when the rip fence  70  is mounted at the left support platform  53  of the left extension frame  50 , as illustrated in  FIG. 2 , the third indicator  93  is aimed at the zero reading of the second scale  82 ; when the rip fence  70  is mounted at the right support platform  63  of the right extension frame  60 , as illustrated in  FIG. 3 , the third indicator  93  is aimed at the zero reading of the third scale  83 . 
         [0021]    Thus, if the workpiece is shorter than the length of the worktable  30 , as illustrated in  FIG. 1 , the user can mount the rip fence  70  at the worktable  30  without needing to extend out the left extension frame  50  or right extension frame  60 . At this time, the distance between the rip fence  70  and the cutter blade  41  (i.e., the size of the workpiece after cutting) can measured using the third indicator  93  and the third scale  83 . 
         [0022]    If the workpiece is too long to be completely received by the worktable  30 , the user can pull out the left extension frame  50  or right extension frame  60  according to the cutting position. If the left extension frame  50  has to be pulled out, as illustrated in  FIG. 2 , the user can mount the rip fence  70  at the left support platform  53  of the left extension frame  50  so that the left end of the workpiece can be abutted against the rip fence  70 , enabling the worktable  30  and the left support platform  53  of the left extension frame  50  to support the workpiece jointly. At this time, the distance between the rip fence  70  and the cutter blade  41  (i.e., the size of the workpiece after cutting) can be measured using the second indicator  92  and the second scale  82 . 
         [0023]    If the right extension frame  60  has to be pulled out, as illustrated in  FIG. 3 , the user can mount the rip fence  70  at the right support platform  63  of the right extension frame  60  so that the right end of the workpiece can be abutted against the rip fence  70 , enabling the worktable  30  and the right support platform  63  of the right extension frame  60  to support the workpiece jointly. At this time, the distance between the rip fence  70  and the cutter blade  41  (i.e., the size of the workpiece after cutting) can be measured using the first indicator  91  and the first scale  81 . 
         [0024]    In conclusion, the table saw  10  provided by the present invention allows the user to selectively use the three scales  81 ˜ 83  and the mating indicators  91 - 93  at three different locations to indicate the cutting length, enhancing the effect of operational convenience.