Grub Screws are a type of fixing screw that’s most often used to join one component or part securely to another.
The design of grub screws means they’re intended to offer this secure gripping or joining facility without the use of a nut, as opposed to the typical arrangement found with most bolts. Despite this key difference, grub screws effectively function much the same as a bolt in practice. Because they’re fully threaded and designed to be driven into an existing tapped hole or socket – rather than driven into the surface, creating a new hole – they’re commonly considered a type of bolt, albeit with a few key differences.
The most obvious point of distinction between grub screws and other types of standard screws and bolts is that true grub screws tend not to feature a protruding head. Instead, they’re usually threaded right to the top, and are the same diameter all the way along their length, meaning that the grub screw can be fully driven into its hole to sit flush with (or even countersunk into, depending on the application) the workpiece.