9/16-20 High Speed Steel, Round Adjustable, Special Thread Die. 1-1/2" Outside Diameter. When cutting threads, a High Speed Steel Round Adjustable Die is is desired for improved wear life. Round Dies are chamfered on both faces. One side has a 2 to 3 thread chamfer for threading, the other side has a 1 to 1-1/2 thread chamfer for threading close to a shoulder. adjustment is obtained bh a fine pitch screw which forces the sides of the die apart, of allows them to spring together. The slot is beveled so that when the dies are used in a machine holder the ajusting screw can be removed and adjjustment made by the adjusting screws in the holder.