Grid Clamp

Technical Details

Standard grid clamps carry loads of 30-75 kg, depending on the model. The clamping range covers pipe diameters from 25mm (1 inch) to 50mm (2 inches). The jaws are made of hardened steel with a ribbed surface or rubber inserts for non-slip grip. The 5/8" spigot (16mm receiver) is the industry standard for fixture mounting. Variants include quick-release clamps with a snap closure, heavy-duty versions up to 100kg load capacity, and special angle clamps for angled mounting.

History & Development

Developed in 1923 by Century Lighting in New York for Broadway theaters, where spotlights had to be mounted on the characteristic iron grids above the stage. Mole-Richardson adapted the system in 1935 for film studios, as similar truss structures were emerging there. The breakthrough came in 1958 with the standardization of the 5/8" spigot by the USITT (United States Institute for Theatre Technology). Modern versions since the 1990s utilize lightweight metal alloys and ergonomic quick-release mechanisms.

Practical Use in Film

In "Blade Runner 2049" (2017), DoP Roger Deakins used grid clamps to mount LED panels on the truss systems of practical sets. Typical workflow: Rigging crew hangs trusses, electricians attach fixtures using grid clamps, final alignment is done via jaw rotation. Advantage: quick repositioning without tools with quick-release systems. Disadvantage: limited load capacity compared to welded mounts, susceptibility to vibration on mobile rigs.

Comparison & Alternatives

Distinction from the C-clamp: Grid clamps for round pipes, C-clamps for flat edges and boards. Safety chains are mandatory additions, not alternatives. Modern alternatives: Magnetic mounts for steel structures (up to 40kg), suction cup systems for smooth surfaces. Quick-rig systems with bayonet locks are increasingly replacing screw clamps in time-critical productions. Permanent installations use permanently screwed mounting plates instead of clamps.