What is the primary purpose of a "set screw"?

The primary purpose of a set screw is to secure an object within or against another object without using a nut. Set screws are typically used in applications where a permanent fastening solution is not necessary, and they help to hold components such as gears, pulleys, or other mechanical parts in position on a shaft or housing. They are designed to be tightened against the surface of the object being secured, creating a friction fit that counters movement. This characteristic makes them especially useful in maintaining the alignment of components while still allowing for easy disassembly when required.

In contrast, while providing additional fastening strength, preventing rotation of a shaft, and aligning components are important aspects of fastening solutions, they do not specifically define the unique functionality and purpose of a set screw.