Coarse-thread self-tapping screw

Self-tapping screws with a coarse thread pitch are used in repair and construction work. The fastener is a sharp-pointed shaft with a conical head, the end of which has a cross recess for a Phillips-type screwdriver or bit.

The single-start thread on the shaft has an increased pitch and a large helix angle. The material is low-carbon steel (typically St20). To increase strength, the fasteners undergo surface heat treatment and carburizing, followed by phosphating or zinc plating. The first method produces black self-tapping screws, the second produces white (zinc-plated) ones.

Application, installation

Coarse-thread self-tapping screws are used for mounting plasterboard and magnesium oxide panels onto wooden battens. The coarse thread allows the fastener to bite into the base well and securely fix the sheets. The countersunk head ensures maximum pressing of the material against the base. Pre-drilling holes before installation is not required.

When ordering coarse-thread self-tapping screws, consider the thickness of the plasterboard and the batten timber. The head should sink into the board by 1 mm without damaging it.