Tools & Gear Hole Saws Screw (Chassis) Punches

7086-22.0 22mm Chrome Alloy Screw (Chassis) Punch A screw punch, also known as a chassis punch or a knockout punch, is used to punch a hole through sheet metal. First drill a pilot hole in the sheet metal the same size as the bolt in the punch. For sizes 13mm and under a Twist drill may be used. For larger sizes use a Bordo step drill. Place the die on to the bolt and then insert this assembly through the pilot hole. Wind the punch onto the bolt and tighten by hand until firm. Turn hex head of bolt with a socket, spanner or wrench until the punch is drawn completely through the sheet metal.