File guide for use in sharpening a chain saw

A file guide for use in sharpening a chain saw, said chain saw comprising a bar, a chain around the periphery of the bar, and a plurality of teeth secured at intervals along the chain, each tooth having a cutting edge at one end thereof constituting its forward end in respect to the direction of movement of the chain, successive teeth of the saw being allochiral relative to each other;

• said guide comprising:
• a frame adapted to be mounted on the bar of the chain saw having means for releasably securing it to the bar;
• a carriage slidably mounted on the frame for forward and rearward movement relative to the tooth to be sharpened and having means for guiding a file for reciprocation at a predetermined angle relative to said tooth through a cutting stroke of the file for sharpening said tooth at said angle and a return stroke, said means for guiding the file comprising a pair of guide members one on one side of the tooth and the other on the other side of the tooth, said guide members being spaced longitudinally of the carriage;
• and
• a stop carried by the frame for holding the tooth against rearward movement;
• said carriage being movable rearward so as to position the file in engagement with the cutting edge of the tooth for the cutting stroke of the file and being movable forward so as to position the file out of engagement with the cutting edge of the tooth for a return stroke of the file.