A grub screw, also known as a set screw is used for securing sliding or moving components in place. Grubs screws have threaded inserts instead of tapering screw grooves. The screw is passed through a threaded hole in the outer object and then tightened against the inner object to prevent it from moving relative to the outer object. Grub screws are commonly used to secure a pulley or a gear to a shaft or for attaching a handle or cam to a spindle. You can learn more in our comprehensive grub screws guide and our complete set screws guide.
These screws can be made from materials such as steel, stainless steel, nylon, brass and ceramic and are available in a wide range of very small sizes.
Types of Grub Screw
Grub Screws are divided into two types, a hexagon head (sometimes called a hexagon set screw) and a socket head.
Hexagon Head Grub Screw - these have a hexagonal head with a thread that extends all the way to the head.
Socket Head Drive Grub Screws - these are headless with recessed drive ports into which you can insert a tool such as a hexagonal Allen key. When used the entire screw is encased in the material it is fastening without any exposed screw or bolt heads making them ideal for mechanical systems where metal surfaces rub together or to provide an aesthetic finish. These are generally more corrosion resistant, can be tightened using more torque and are secure and difficult to remove.
Grub screws have different drive types, including a straight slot for a standard flat screwdriver, a hex socket, a square socket, an external hex, an external square or a Bristol spline.
Grub screws also have a range of different point types which mean they can be used for a range of different applications.
Flat Point screws are used where a screw must press flat against a surface.
Domed Point screws apply pressure to the part opposite the screw head.
Cone Point and Cup Point screws apply force to soft materials or to fit into a depression to the part opposite the screw head. Cup point screws apply a greater force.
Knurled Point screws are like cup point screws but have parallel serrations with a ratchet-locking action preventing loosening due to vibration.
Extended Point or Dog Point screws have a cylindrical head at the end which can be used as a pivot shaft for other parts that need to rotate around it.