A set screw, also called a grub school in British English, is a type of screw generally used to secure an object within another object. The set screw passes through a threaded hole in the outer object and is tightened against the inner object to prevent it from moving relative to the outer object. It exerts its clamping force through the bottom tip that projects through the hole rather than with a larger head that remains outside.

Among other uses, set screws are used to secure gears and wheels on shafts, preventing both sliding and rotation.

Set screws appear with a variety of tip types, including the following:

• Flat Point
• Domed Point
• Cone Point
• Cup Point
• Knurled Cup Point
• Dog Point

They also appear with a variety of drive styles, including the following:

• Allen (hex)
• Square head
• Slotted
• Bristol® spline

External link

• Page illustrating various set screw tip types

Screws | Stellschraube