All About Set Screws

Unlike standard screws that feature a head on one side, Set Screws are commonly devoid of a head and feature helical external threading that will often encompass the entirety of the component’s length. When the set screw features threading across its whole body, the component may be referred to as a cap screw in the United States. The lack of a head and the length of threading on set screws is highly beneficial for many applications due the ability to avoid protrusion.  When a set screw is embedded within a gear and pulley assembly, for example, the headless body will allow the screw to secure the assembly without affecting its functionality. Despite their various differences from standard screws, they may still secure an object without the use of a mating nut, such as is seen with other various types.
 
For the installation of set screws, such components are often driven into an assembly with the use of an internal wrenching drive, allen key, or Robertson sockets and slots. Once the set screw has been successfully installed into the assembly, parts are secured together with a clamping force. As set screws face the risk of slipping, one may mill or ground a detent at the area where the set screw’s point contacts. This may also create an increased load capacity, and the detent should always be aligned with the threaded hole before the fastener is installed.

Set screws are often constructed with a number of materials, all of which can determine operational limits, resistances, strengths, and more. Generally, the most common materials for manufacturing such fasteners include aluminum, titanium, and steel. Alloy steel socket set screws are known for their robust qualities, allowing them to perform with long service lives as compared to other various types.
 
Beyond materials, set screws also may vary in the type of point that they feature, that of which is the fastener’s tip shape. Tip selection will commonly be determined by the qualities desired for the assembly, as a flat tip can benefit installation against a flat surface while reduced surface area of contact can be achieved with a tip shape such as a cut point. Beyond such examples, there are also domed points, extended points, cone points, and knurled cup points. Knurled cup points in particular are beneficial for fastening a component within another component, also allowing for loosening to be prevented when vibration occurs. Meanwhile, other point types may benefit standard component assembly, and one should always consider accessibility, the presence of corrosive materials, weight restrictions, materials that are being joined, and other factors before making a decision.