Spoil Board Cutters are an integral part of cnc maching if you own a flat bed cnc machine. The purpose is to remove the top layer of the waste board or spoilboard which is typically made of a low density mdf. We offer two sizes a 4″ and a 2.5″. The diameter is an important consideration for larger machines. A larger diameter for a spoilboard cutter can reduce the time for planing by 50%. You can also reduce planing time by an additional 30% if you change from a 2 wing to a 3 wing and increase the feed rate. replacement inserts are a 14x14x2