This precision-machined hob is of the highest quality. It is designed for a 8 mm shafted stepper motor with a keyed side so as to provide a firm hold. This hob offers many improvements over typical hobbed bolts, as the "threads" have a much steeper angle and are precisely located. This includes the hob and the allen set screw.
This is the hob used on the MendelMax 2 and the Fusematic printer with a geared stepper on the extruder..