This article refers to the clamp used to hold together two workpieces. For clamps used to secure stage lighting instrument

Stage lighting instrument

Stage lighting instruments are used in stage lighting to illuminate theatrical productions, concerts, and other performances taking place in live performance venues. They are also used to light television studios and sound stages.Many stagecraft terms vary between the United States and the United...

s to battens

Batten (theater)

In theater, batten refers to a long metal pole suspended above the stage or the audience from which lighting fixtures, theatrical scenery, tabs or other curtains may be hung...

, see C-Clamp (stagecraft)

C-Clamp (stagecraft)

In stagecraft, a c-clamp can refer to a number of different pieces of hardware, depending on its intended use.-Lighting and sound:In stage lighting and sound a c-clamp, also referred to as a pipe clamp, is used to attach a larger piece of hardware, such as a lighting instrument, a speaker, or a...

. For the Chicago Indie Rock band, see C-Clamp

C-Clamp (band)

C-Clamp was an indie rock band from Chicago, by way of Urbana-Champaign, Illinois.- Band history :Sometimes referred to as slowcore, C-Clamp placed emphasis on mood, texture and rhythm. Known for their dense layering and simple, yet beautiful vocal harmonies, C-Clamp released only two full length...

A C-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...

 device typically used to hold a wood

Wood

Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...

 or metal

Metal

A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 workpiece, and are often used in, but are not limited to, carpentry and welding. These clamps are called "C" clamps because of their C shaped frame, but are otherwise often called G-clamps or G-cramps because including the screw part they are shaped like an uppercase letter G.

Description

C-clamps or G-clamps are typically made of steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 or cast iron

Cast iron

Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

, though smaller clamps may be made of pot metal

Pot metal

Pot metal, also known as monkey metal, white metal or die-cast zinc, is a slang term that refers to alloys that consist of inexpensive, low-melting point metals used to make fast, inexpensive castings....

. At the top of the "C" is usually a small flat edge. At the bottom is a threaded hole through which a large threaded screw protrudes. One end of this screw contains a flat edge of similar size to the one at the top of the frame, and the other end usually a small metal bar, perpendicular to the screw itself, which is used to gain leverage when tightening the clamp. When the clamp is completely closed, the flat end of the screw is in contact with the flat end on the frame. When the clamp is actually used, it is very rare that this occurs. Generally some other object or objects will be contained between the top and bottom flat edges.

Usage

A C-clamp is used by means of turning the screw through the bottom of the frame until the desired state of pressure or release is reached. In the case that the clamp is being tightened, this is when the objects being secured are satisfactorily secured between the flat end of the screw and the flat end of the frame. If the clamp is being loosened, this is when a sufficient amount of force is released to allow the secured objects to be moved.

Woodworking

While a C-clamp is a useful tool for woodworking, special care should be taken when working with delicate woods. The flat gripping edges of the frame, generally no larger than half an inch or a centimetre (depending on the size of the clamp) can cause indentations and marring of the surfaces being clamped. This can be avoided by buffering between the clamp and the timber using two pieces of scrap wood. As each piece of scrap wood is directly in contact with the flat edges of the frame and with the items being clamped, this allows the scrap wood to receive the damage from the clamping, while dispersing the clamping force across the piece of scrap wood into the clamped objects. Deep-throated clamps are also available and provide far greater reach for smaller jobs.