Method of forming a tapped hole

摘要

A tapped hole produced in a metallic material by threading a preselected standard threaded fastener into an untapped hole formed in the material. The diameter of the hole to be formed is determined by using a formula that takes into account the hardness and thickness of the material to be tapped and the basic major diameter and pitch of the preselected threaded fastener to be used to tap the hole. This formula can only be used with threaded fasteners having threads of the Unified Thread Standard type. This formula is particularly useful in tapping a hole formed in a mounting strap of an electrical wiring device.