Set Screw

A set screw is a rod with external thread designed for rigid fastening of parts (locking). Unlike a machine screw, a set screw has no head.

The end face carries slots of various shapes (slot, cross recess) or a hex socket. The opposite end of the screw (the point) can be flat, rounded, cup, half-dog, cone, oval, or in the form of a pivot. Set screws are made from structural steel grades St 35 and St 45, and heat-treated to increase hardness.

Application and installation

Set screws are a component of mechanisms, machine tools and other equipment. Set screw fasteners are used to secure bushings, gears and pulleys mounted on a shaft in the radial and axial directions. After the assembly is put together, a hole is drilled and tapped in the adjoining parts. The screw is driven in with a screwdriver of the matching shape, sunk flush with the surface. The point is seated in the hole and keeps the parts from shifting.