Most commonly used to fasten metal to metal, a machine screw is designed to be inserted into a pre-threaded hole or mated with a nut (in which case it would be called a stove bolt). A machine screw is like a small diameter bolt, like a bolt or hex head cap screw (paired with a hex nut), but is usually driven with a screwdriver instead of a wrench. It features a straight, untampered shank and blunt end. External machine thread runs the entire length of the shank. Because application thread sizes and head types vary, it is important to select the right machine screw and washers to meet your needs.