Safety systems for power equipment

Abstract

A saw with a safety system is disclosed. The safety system includes a detection system adapted to detect contact between a person and a blade while the blade is moving. The safety system further includes a brake system adapted to engage the blade and to stop the blade when the detection system detects contact between the person and the blade.

1 . A method of operating a saw comprising: 
 providing a blade configured to move to cut a work piece, where the blade includes a cutting edge;    providing a motor adapted to move the blade;    providing a detection system adapted to detect a dangerous condition between a person and the blade while the blade is moving and to distinguish that dangerous condition from proximity between green wood and the blade by imparting a signal to the blade and monitoring that signal for a predetermined change indicative of the dangerous condition;    providing a reaction system adapted to take some action to mitigate possible injury if the detection system detects the dangerous condition; and    moving the blade to cut a work piece while the detection and reaction systems are active.    
   
   
       2 . The method of  claim 1 , where the dangerous condition is contact between a person and the blade.  
   
   
       3 . The method of  claim 1 , where the dangerous condition is proximity between a person and the blade.  
   
   
       4 . The method of  claim 1 , where the predetermined change indicative of the dangerous condition is a predetermined rate of change.  
   
   
       5 . The method of  claim 1 , where the reaction system includes a retraction mechanism to retract the blade.  
   
   
       6 . The method of  claim 1 , where the reaction system includes a brake to decelerate the blade.  
   
   
       7 . The method of  claim 6 , where the brake includes a pawl and a system to move the pawl into contact with the blade.  
   
   
       8 . The method of  claim 7 , where the system to move the pawl into contact with the blade causes the pawl to contact the blade within  10  milliseconds after the detection system detects the dangerous condition.  
   
   
       9 . The method of  claim 1 , where the saw is a table saw.  
   
   
       10 . The method of  claim 1 , where the saw is a miter saw.  
   
   
       11 . The method of  claim 1 , where the saw is a hand-held circular saw.  
   
   
       12 . A method of operating a saw comprising: 
 providing a blade configured to move to cut a work piece, where the blade includes a cutting edge;    providing a motor adapted to move the blade;    providing a detection system adapted to detect a dangerous condition between a person and the blade while the blade is moving and to distinguish that dangerous condition from contact between green wood and the blade by imparting a signal to the blade and monitoring that signal for a predetermined change indicative of the dangerous condition;    providing a reaction system adapted to take some action to mitigate possible injury if the detection system detects the dangerous condition; and    moving the blade to cut a work piece while the detection and reaction systems are active.    
   
   
       13 . The method of  claim 12 , where the dangerous condition is contact between a person and the blade.  
   
   
       14 . The method of  claim 12 , where the dangerous condition is proximity between a person and the blade.  
   
   
       15 . The method of  claim 12 , where the predetermined change indicative of the dangerous condition is a predetermined rate of change.  
   
   
       16 . The method of  claim 12 , where the reaction system includes a retraction mechanism to retract the blade.  
   
   
       17 . The method of  claim 12 , where the reaction system includes a brake to decelerate the blade.  
   
   
       18 . The method of  claim 12 , where the saw is a table saw.  
   
   
       19 . The method of  claim 12 , where the saw is a miter saw.  
   
   
       20 . The method of  claim 12 , where the saw is a hand-held circular saw.