The ductile cast iron body and working surface are accurately machined and ground so that the sole and sides are flat and square. The plane's adjustable toe lets you narrow the mouth for very fine shavings with minimum tear-out. sharpening replace it without lateral adjustment. The blade is made of tool steel hardened to Rc60-62. The shoulder plane is like a rebate plane, in that the blade extends, therefore cuts, to the full width of the tool. The shoulder plane is used to trim the shoulders and faces of tenons. It is used when it is necessary to trim right into the concave corner where two surfaces of the same piece of wood meet perpendicularly. Unlike the rebate plane, the shoulder plane is intended to cut end grain. There are therefore differences between it and a rebate plane in the angles at which the iron (blade) is set. There is a more acute angle between the iron and the sole of the tool. The iron is set square across the tool rather than obliquely. The iron is set face down. The ground and honed bevel forming the edge, is uppermost. A shoulder plane also has a much finer set mouth, which allows finer shavings to be taken.