DEFECTING SAW

A defecting saw including a feed conveyor and a transversely movable rotating saw, both of which are controlled by means of a control circuit including a light detector for detecting fluorescent marks placed on a board to identify a defect area. An ultraviolet light source is mounted adjacent the saw blade together with the light detector such that, as a board is fed into the saw blade area by the feed conveyor, the detector will detect light from the illuminated fluorescent mark. The light detector is coupled to the control circuit which operates to stop the feed conveyor and simultaneously swing the rotating saw transversely across the board at the fluorescent mark. After a cut is made, the feed conveyor again starts until the next fluorescent mark is detected. Defects are thereby automatically cut away from the board when they are marked on either side by such fluorescent marks.