An F-clamp, also known as a bar clamp or speed clamp and a "G-clamp", is a type of clamp

Clamp (tool)

A clamp is a fastening device to hold or secure objects tightly together to prevent movement or separation through the application of inward pressure...

. The name comes from its "F" shape. The F-clamp is similar to a C-clamp

C-clamp

A C-clamp is a type of clamp device typically used to hold a wood or metal workpiece, and are often used in, but are not limited to, carpentry and welding...

 in use, but has a wider opening capacity (throat). This tool is used in woodworking

Woodworking

Woodworking is the process of building, making or carving something using wood.-History:Along with stone, mud, and animal parts, wood was one of the first materials worked by early humans. Microwear analysis of the Mousterian stone tools used by the Neanderthals show that many were used to work wood...

 while more permanent attachment is being made with screw

Screw

A screw, or bolt, is a type of fastener characterized by a helical ridge, known as an external thread or just thread, wrapped around a cylinder. Some screw threads are designed to mate with a complementary thread, known as an internal thread, often in the form of a nut or an object that has the...

s or glue

Wood glue

Wood glue is an adhesive used to tightly bond pieces of wood together. Many substances have been used as glues.-Types of wood glue:* For many centuries animal glue, especially hide glue was the traditional glue for all kinds of woodwork. It is still used today, mainly for musical instruments and...

, or in metalworking

Metalworking

Metalworking is the process of working with metals to create individual parts, assemblies, or large scale structures. The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewelry. It therefore includes a correspondingly wide range of skills,...

 to hold pieces together for welding

Welding

Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, with pressure sometimes...

 or bolting.

An F-clamp consists of two horizontal bars joined together by a vertical bar. There is a large screw on the lower bar to allow for the clamp to be tightened. The clamp is really more of a "G" shape with the vertical stalk of the G being the screw. Some F-clamps are adjustable which allows for them to be used on larger scale objects without the need for a large screw.

An F-clamp is also a simple mechanical device used for lifting engine or transmission

Transmission (mechanics)

A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...

 parts. The clamp has an adjusting screw to tighten onto the part and a lifting ring to attach a hoist cable.

F-clamps in the industry terminology have the jaws mounted on a flat bar, while a pipe clamp

Pipe clamp

A pipe clamp is a type of clamp often employed in woodworking or cabinet shops. It is, usually, comprised, of commercially manufactured clamp heads or "jaws" and a length of common threaded pipe. The capacity of the clamp is determined by the length of the pipe used.-Description:A pipe clamp uses...

, which has the same construction, is mounted on a pipe, normally of 1/2" or 3/4" diameter.