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.
• Often used on barrel nuts and mating screws.