A shoulder screw, also called a shoulder bolt, has a shank with a larger diameter immediately below the head that “steps down” to a smaller diameter for the threaded length. The change in diameter provides a “shoulder,” which can be firmly tightened against the part to that which it is screwed.
Much like all other screws, shoulder screws are meant to hold objects together and in a particular position. However, these screws are designed for use in parts which requires a mounting pin, joint, shaft, dowel, pivot, or sliding motion. Items such as: Bearings.
The shoulder screw is comprised of three main features: The “head” which is the largest diameter, the “shoulder” which is described by its diameter and length and the “thread” whose major diameter must be slightly smaller than the shoulder diameter.
They do not generally have a pointed tip, which means that predrilling is necessary. Mated nuts will also need to be used and often washers are a good idea as well, depending on how much pressure the fasteners will be under.
