Abstract:
A rip fence for movable and positionable use on a worktable of a cutting machine includes an adjusting handle for control locking of the fence to the worktable, and a trigger, which keeps the fence locked to the worktable when it is not pressed and, which enables the user to unlock the fence from the worktable by operating the adjusting handle when it is pressed.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to a rip fence used with a worktable of a cutting machine, such as table saw. 
   2. Description of the Related Art 
     FIG. 1  shows a conventional rip fence  2  installed on the worktable  1   a  of a table saw  1 . The rip fence  2  can be moved on the top surface of the worktable  1   a  to the desired position and then locked. The rip fence  2  comprises a fence body  2   a  approximately equal to the width of the worktable  1   a , a fence adjusting handle  2   b  pivoted to one end of the fence body  2   a , a front clamp  2   c  pivoted to the front end of the fence body  2   a  corresponding to the front side of the worktable  1   a , a rear clamp  2   d  pivoted to the rear end of the fence body  2   a  corresponding to the rear side of the worktable  1   a , and a linking mechanism (not shown) connecting the front clamp  2   c  and the rear clamp  2   d  to the fence adjusting handle  2   b . The fence adjusting handle  2   b  is turnable relative to the fence body  2   a  between the pressed position as shown in  FIG. 1  where the front clamp  2   c  and the rear clamp  2   d  are respectively clamped on the front and rear sides of the worktable  1   a  to lock the fence body  2   a  to the worktable  1   a , and the lifted position as shown in  FIG. 2 , where the front clamp  2   c  and the rear clamp  2   d  are respectively disengaged from the worktable  1   a  for enabling the user to move the fence body  2   a  on the top surface of the worktable  1   a  to the desired position. This structure of rip fence  2  is functional, however it is not safe in use. During cutting operation, the fence adjusting handle  2   b  may be lifted accidentally to unlock the fence body  2   a . If the user keeps operating the sawing machine at this time, an accident may occur. 
   SUMMARY OF THE INVENTION 
   The present invention has been accomplished under the circumstances in view. It is the primary objective of the present invention to provide a rip fence, which is easy to adjust and safe in use. 
   To achieve this objective of the present invention, the rip fence, which is movable on and lockable to a worktable of a machine, comprises a main body having a front end and a rear end, an adjusting handle pivoted to the front end of the main body, a trigger pivoted to the adjusting handle and turnable between a first position and a second position, a clamp provided at the rear end of the main body and having a stop portion stoppable at a rear end of the worktable, and a link coupled between the adjusting handle and the clamp. The trigger has a stop portion, which is stoppable against a front end of the worktable when the trigger is moved to the first position and is away from the front end of the worktable when the trigger is moved to the second position, and a pressable portion which can be pressed by a user to move the trigger from the first position to the second position. When the trigger is positioned at the second position and the adjusting handle is lifted relative to the main body, the link will be forced to move the clamp away from the worktable, for enabling the rip fence to be moved on the worktable to a desired position. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic drawing showing a rip fence locked to the worktable of a sawing machine according to the prior art. 
       FIG. 2  is similar to  FIG. 2  but showing the unlocked status of the rip fence. 
       FIG. 3  is a schematic drawing showing a rip fence installed on the worktable of a sawing machine according to the present invention. 
       FIG. 4  is an exploded view of the rip fence according to the present invention. 
       FIG. 5  is a sectional view showing the rip fence locked to the worktable according to the present invention. 
       FIG. 6  is similar to  FIG. 5  but showing the trigger pressed. 
       FIG. 7  is similar to  FIG. 6  but showing the adjusting handle lifted, the rip fence unlocked. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   As shown in  FIGS. 3–5 , a rip fence  100  is slidably mounted on the top of the worktable  200  of a cutting machine (for example, a table saw). The rip fence  100  comprises a main body  10 , an adjusting handle  18 , a trigger  28 , a spring member  32 , a clamp  36 , and a link  40 . 
   The main body  10  has a front end  10   a  and a rear end  10   b , and is comprised of a channel bar  12 , a guiding seat  14  and a stop plate  16 . The guiding seat  14  is provided at one end of the channel bar  12 . The stop plate  16  is set near the rear end  10   b  of the main body  10 , having a through hole  16   a . The guiding seat  14  has a transverse hole  14   a , and a window and index structure (not shown) through which the user can see the indication of the graduations on the worktable  200  indicative to the length of the workpiece under cutting. 
   The adjusting handle  18  is comprised of a grip  20  and a coupling frame  22 . The grip  20  is orthopedically engineered for comfortable gripping with the hand, having a mounting hole  20   a . The coupling frame  22  is an open frame having a first through hole  22   a , a second through hole  22   b , and a third through hole  22   c . As shown in  FIGS. 4 and 5 , a pivot pin  24  is fastened to the transverse hole  14   a  of the guiding seat  14  and the first through hole  22   a  of the coupling frame  22  to pivotally couple the adjusting handle  18  to the guiding seat  14  of the main body  10 , so that the adjusting handle  18  is turnable about the pivot pin  24  relative to the guiding seat  14  between two reversed directions. Further, a pin  26  is inserted through the second through hole  22   b  of the coupling frame  22  and connected firmly with the coupling frame  22 . 
   The trigger  28  has a hooked stop portion  28   a , a pressable portion  28   b , a through hole  28   c , and an arched guiding hole  28   d . A pivot pin  30  is fastened to the third through hole  22   c  of the coupling frame  22  and the through hole  28   c  of the trigger  28  to pivotally secure the trigger  28  to the coupling frame  22  of the adjusting handle  18 , for enabling the trigger  28  to be turned relative to the adjusting handle  18  between a first position where the hooked stop portion  28   a  is stopped against the worktable  200 , and a second position where the hooked stop portion  28   a  is kept away from the worktable  200 . The pressable portion  28   b  is maintained extended out of the coupling frame  22  for pressing by the finger of a user for moving the trigger  28  from the first position to the second position. 
   The spring member  32  is a coil spring mounted on the pivot pin  30 , having one end stopped against one side of the coupling frame  22  and the other end stopped against the trigger  28 . The spring member  32  imparts a push force to the trigger  28  to force the hooked stop portion  28   a  into contact with the front bottom side of the worktable  200 . Further, a guiding pin  34  is inserted through the mounting hole  20   a  of the grip  20  and the arched guiding hole  28   d  of the trigger  28  to guide movement of the trigger  28  stably between the first position and the second position. 
   The clamp  36  is a plate member provided at the rear end  10   b  of the main body  10 , having a through hole  36   a  and a stop portion  36   b . Further, a coil spring  38  is stopped between the stop plate  16  and the clamp  36 . 
   The link  40  is a rod member longitudinally inserted in proper order through the main body  10 , the through hole  16   a  of the stop plate  16 , the spring  38 , and the through hole  36   a  of the clamp  36 , having one end terminating in a hook  40   a , which is hooked on the pin  26 , and the other end terminating in a screw rod  40   b , which is screwed up with a nut  42 . 
   The positioning of the rip fence  100  on the worktable  200  and its adjustment are outlined hereinafter with reference to  FIGS. 5–7 . 
     FIG. 5  shows the rip fence  100  locked to the worktable  200  where the adjusting handle  18  is kept suspended downwards, the hooked stop portion  28   a  of the trigger  28  is forced by the spring member  32  into contact with the front bottom side of the worktable  200 , and the clamp  36  is dragged by the link  40  to keep the stop portion  36   b  stopped at the rear side of the worktable  200 . 
   When wishing to unlock the rip fence  100  from the worktable  200 , press the pressable portion of the trigger  28  to move the hooked stop portion  28   a  away from the worktable  200  (see  FIG. 6 ), and then turn the adjusting handle  18  upwards to change the position of the pin  26 , as shown in  FIG. 7 . At this time, the spring  38  pushes the clamp  36  outwards from the worktable  200 , and therefore the rip fence  100  is unlocked and can be moved on the worktable  200  to a desired position. After the rip fence  100  has been moved on the worktable  200  to the desired position, turn the adjusting handle  18  downwards to lock the rip fence  100  to the worktable  200  again, as shown in  FIG. 5 . 
   As indicated above, when the user touches the adjusting handle  18  accidentally without pressing the trigger  28  during cutting operation, the rip fence  100  is maintained locked to the worktable  200 . Therefore, the trigger  28  ensures safety use of the rip fence  100 . 
   Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.