Screw/Bolt Type Table of Contents
Fastener Head & Drive Table of Contents
Varieties of Screws/Bolts
Wood Screw
- Has a sharp point.
- Generally has an unthreaded shank below the head.
- Designed to attach 2 pieces of wood.
Sheet Metal Screw
Use sharp points and threads and are designed to be driven directly into sheet metal. They can also be used in softer material like plastic, fiberglass, and wood.
Self Drilling Sheet Metal Screw
Sheet metal screw with a self-drilling point.
Machine Screw
- Smaller fastener threaded the entire length of the shank.
- Usually has a recessed drive type.
- Has a thread class.
Thread-Cutting Machine Screw
- Machine screw with a thread-cutting (self-tapping) point.
Set/Grub Screw
- Is headless.
- Fix a rotating part to a shaft.
- Used only for transmitting very light loads.
Socket Screw
- A machine screw with an internal hex socket (Allen) drive. longer lengths may have a smooth upper shank.
Shoulder Screw/Bolt
- Shank is ground to a precise diameter and threaded portion is smaller in diameter then the shoulder. These fasteners can be used to create a pivot point.
Barrel Nut/ Mating Screw
- Used for through-bolting applications where a head is desired on both sides of the joint.
Fastener Heads
Flat Head
- A countersunk head with a flat top.
Round Head
- A domed head.
Oval Head
- A countersunk head with a rounded top.
Hex Head
- A hexagonal head, can have a washer or flange modification.
Slotted-Hex-Washer Head
- A hex head with a built-in washer and slotted drive.
Button Head
- A low profile rounded head using a socket drive.
Socket Head
- A small cylindrical head using a socket drive.
Drive Types
Socket/Hex/Allen Drive
- Hexagonal hole for use with an Allen wrench.
- Often used in bicycle maintenance and furniture.
Phillips and Frearson Drive
- An X shaped drive.
- Designed to cam-out after a certain torque limit.
Slotted Drive
- A slot in the head, used with a flathead installation tool.
- Most popular.
- Less likely to have rounded or stripped slots.
Combination Drive
- A combination of slotted and Phillips drives.
Square/Robertson Drive
- A square-shaped drive type.
- Often used in automotive and furniture industries.
- Has the highest torque tolerance.
Star/Torx Drive
- A six-pointed star pattern specifically designed to prevent cam-out and stripped heads.
One-way Drive
- Installs with a normal slotted or "flathead" installation tool but can not be removed without special tools.
