WHILE USING 1/2"" DRILL MOTOR ALONG WITH A HOLE SAW ATTACHMENT, EE WAS DRILLING A HOLE IN SOME INSULATING MATERIAL WHEN THE HOLE SAW HUNG UP ONSOME MATERIAL. THE HOLE SAW SUDDENLY STOPPED FOR WARD MOTION CAUSING THE DRILL MOTOR TO TURN IN OPPOSITE DIRECTION IN SUDDEN VIOLENT MANNER. THEMOVEMENT TWISTED HIS HAND & WRIST.