EMPLOYEE WAS MODIFYING COMPACTOR CONVEYOR BELT GUARD BY INSTALLING A HINGED 36'X36' ACCESS DOOR TO MAKE IT EASIER FOR THE OPERATORS TO GET TO AREA. HE WAS ATTEMPTING TO MOVE GUARD FOR BETTER WELDING ACCESS WHEN HINGED DOOR FELL CATCHING TIP OF LEFT RING FINGER BETWEEN 1/2' ANGLE IRON ON THE GUARD AND HINGED DOOR RESULTING IN CONTUSION AND FRACTURE TO BONE ON END OF FINGER.