Ball Shape All sizes are nominal. Sizes marked * are 3mm shank, all others are 6mm shank. Cut Numbers: Cut 3 - Rapid Cut For use on softer non-ferrous and plastic materials, i.e. aluminium, fibreglass, plastics, hard rubber and zinc alloy. Cut 9 - Chipbreaker Chipbreaker fast stock removal for improved control and reduced chips for use on hard materials, i.e. steel alloy 50RC, 60RC, carbon and cast iron.