C-Clamp (stagecraft)
Encyclopedia
In stagecraft
Stagecraft
Stagecraft is a generic term referring to the technical aspects of theatrical, film, and video production. It includes, but is not limited to, constructing and rigging scenery, hanging and focusing of lighting, design and procurement of costumes, makeup, procurement of props, stage management, and...

, a c-clamp can refer to a number of different pieces of hardware, depending on its intended use.

Lighting and sound

In stage lighting
Stage lighting
Modern stage lighting is a flexible tool in the production of theatre, dance, opera and other performance arts. Several different types of stage lighting instruments are used in the pursuit of the various principles or goals of lighting. Stage lighting has grown considerably in recent years...

 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
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...

, a speaker, or a dimmer
Dimmer
Dimmers are devices used to vary the brightness of a light. By decreasing or increasing the RMS voltage and, hence, the mean power to the lamp, it is possible to vary the intensity of the light output...

, to a pipe or batten
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...

. Newer c-clamps tend to be constructed of aluminum, although 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...

 is also available.

C-clamps function by affixing a bolt (the "shaft bolt") to the hardware they are to hold in place, such as through the yoke of a lighting instrument, and securely fastening this bolt to the clamp shaft. The open end of the clamp is then placed over the batten, and a bolt (the "clamp bolt") is tightened to secure the c-clamp. C-clamps for stage lighting fixtures usually also have a pan screw (also known as a "grub bolt"), which when loosened will allow the clamp shaft, and therefore the fixture, to be rotated 360 degrees while maintaining a secure connection to the batten.

When using c-clamps care must be taken to not over-torque the clamp bolt which affixes the clamp to the batten. If this bolt is over-tightened, it can easily dimple or "drill" into the batten seriously compromising the strength of the batten.

Parts

  • Clamp: the main body of the clamp, is typically either cast steel or aluminium and designed to sit overtop of a typical theatrical batten
    Batten
    A batten is a thin strip of solid material, typically made from wood, plastic or metal. Battens are used in building construction and various other fields as both structural and purely cosmetic elements...

    .
  • Clamp Bolt: a long-threaded bolt (typically 9/16") designed to tighten down on a pipe, forcing it into the clamp.
  • Spigot: a machined metal shaft that sits in the clamp and rotates freely through 360°. Used for attaching 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...

     or other fixture to the c-clamp.
  • Pan Bolt: A small bolt through the side of the clamp, typically 1/4" or 3/8" which tightens down onto the spigot, preventing it from rotating (panning).
  • Yoke Bolt: A short 1/2" bolt which affixes the yoke of a fixture to the spigot.

Variations

  • Pipe Clamp
  • G clamp
  • Trigger Clamp
  • Cheseborough
  • Manfrotto
    Manfrotto Group
    Manfrotto is a brand manufactured by Lino Manfrotto + Co. Spa, a company headquartered in Bassano del Grappa, Italy. Manfrotto is a worldwide leading brand in the manufacturing of camera and lighting supports. Manfrotto is owned by the UK company The Vitec Group, which purchased Lino Manfrotto +...

     Super Clamp

Film and television

Film and television grips
Grip (job)
In the U.S. and Canada, grips are lighting and rigging technicians in the filmmaking and video production industries. They constitute their own department on a film set and are directed by a key grip. Grips have two main functions...

 commonly make use of c-clamps that are manufactured specifically for their industry. These clamps are produced with integrated studs designed to accept the mounting hardware from a variety of small, lightweight lighting fixtures, allowing illumination to be placed in unusual or awkward locations quickly and easily.

Carpentry

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...

s are commonly used in theatrical carpentry
Carpentry
A carpenter is a skilled craftsperson who works with timber to construct, install and maintain buildings, furniture, and other objects. The work, known as carpentry, may involve manual labor and work outdoors....

 for the same purpose that non-theatrical carpenters employ them: for creating a quick, temporary, and non-destructive way of joining two objects together. Legs are commonly attached to platforms
Platform (theatre)
In theatre, a platform is a stationary, standard flat walking surface for actors to perform on. Typically, they are built to be assembled modularly. They are often used to provide varying levels, to make a show more visually interesting. They are also used to separate areas on stage, and as...

 via c-clamp before they are fastened together using a more permanent method (i.e. bolts
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...

). Multi-platform assemblies are also commonly joined to one another solely with c-clamps, especially in touring
Touring theatre
A touring company is an independent theatre or dance company that travels, often internationally, being presented at a different theatre in each city....

situations where a set needs to be assembled and struck quickly.
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