What Is a Machine Screw?
A machine screw, also sometimes referred to as a machine bolt, is a screw that is typically designed to be fastened to an existing, tapped hole on a metal surface, usually in conjunction with a corresponding nut. These types of screws are not as large as the average screw, usually ranging in sizes up to three quarters of an inch (19.05 mm) but they can still be larger. Variations between machine screws mainly exist in overall size, shape of the head, slot type, length, material, and characteristics of the thread. A major way of categorizing a machine screw is by the type of slot in the head, which will determine the kind of screwdriver that is to drive it into its hole. The two major kinds of screwdrivers used with machine screws are slotted and Phillips head screwdrivers, but there are several other minor types of screw drive holes such as Torx — six-pointed, star-shaped drive holes — that require more specialized screwdrivers. Specialized types of screw drive holes may be important w
