A set screw is a specialized fastening device that serves the crucial purpose of securing one object within or against another object through the application of pressure and/or friction. This mechanical component is commonly employed in various applications, such as fixing pulleys, gears, or other rotating components to shafts. Unlike traditional bolts that require nuts for fastening, a set screw functions independently by being threaded directly into a pre-drilled and tapped hole in one of the two objects being secured.

One distinctive characteristic of set screws is their design versatility. They often come in a headless configuration with threading that runs along their entire length, allowing them to sit completely flush within the threaded hole. In such cases, these fasteners are alternatively known as grub screws or blind screws.

The installation process involves screwing the set screw into the first object until it is properly positioned and securely tightened. The protruding tip of the set screw then exerts significant pressure against the second object, effectively creating a strong clamping force between the two components.

To enhance the security and prevent unwanted movement, the second object may feature a specially machined detent or recess. In the case of shafts, this could be as simple as a flattened surface area that provides a stable contact point for the set screw.

The versatility of set screws is further demonstrated in their various drive types, which can include hex heads, square heads, slotted drives, or recessed designs. This range of drive options allows for different installation methods and tools to be used, making set screws adaptable to various assembly requirements and accessibility constraints.