Screwpin

Screwpin is a term with no single universally accepted definition in standard fastener nomenclature. It may refer to a fastener that combines characteristics of a screw and a pin, or it may be a regional or nonstandard spelling of “screw pin” or “threaded pin.” Because of this variability, the form and use of a screwpin can differ across industries and suppliers.

In the most common interpretation, a screwpin describes a threaded pin fastener. This is a cylindrical pin whose shank carries external threads along part or all of its length. It is installed by turning the pin with an appropriate tool, so that it threads into a tapped hole or into a nut, providing clamping and positional retention. Some variants are headless to sit flush with the surrounding surface, while others include a drive head for easier installation. Materials typically include steels (carbon or alloy) and stainless steels, with various coatings.

Other uses of the term may appear in catalog language or informal writing to mean any threaded pin or miniature screw-like fastener, rather than a distinct part type. In practice, engineers and machinists often prefer to specify alternatives such as bolts, set screws, rivets, or standard threaded pins to avoid ambiguity.

Specification and selection usually call for the overall length, major diameter, thread pitch or form, head type, material, finish, and drive method.

See also: screw, pin, threaded fastener, rivet, set screw.