Cap Screws 1×31/4 Large Head 12.9 UNC

A socket cap screw, also known as a socket head, cap screw, socket screw, or Allen bolt, is a type of cap screw with a cylindrical head and hexagonal drive hole. Socket head cap screws are commonly used in assemblies that do not provide sufficient clearance for a conventional wrench or socket.nThe head has a larger diameter than the threaded portion, this provides a positive mechanical stop when tightening the screw. Cap screws are tightened directly into a threaded or tapped hole, usually without a nut.nSocket head cap screws are typically used in machine parts, die fixturing, and clamping.nThe most basic difference between a cap screw and a bolt is the way in which these fasteners are installed. Technically, a bolt is installed by turning a nut to tighten the fastener, while a cap screw is installed by turning the head of the bolt to assemble and tighten.