We have come up with a grub screw, also called a set screw, which is a type of screw that is designed to be tightened against a flat surface or another object to hold it in place. These are typically small & feature a hexagonal or cylindrical head that can be tightened with an Allen key or screwdriver. Grub screws are often used to secure rotating components such as gears or pulleys onto shafts or to fix components in place on machinery.