DIY Frequently Asked Questions / C-Clamp')">
The most common type of clamp—consists of a C-shaped frame, made of either forged steel or cast iron, into which an adjustable screw is assembled to change the jaw opening.
The size of a C-clamp is measured by its jaw capacity—the dimension of the largest object the frame can accommodate with the screw fully extended. Most range in jaw capacity from 2” to 10”.
Also important is depth of throat, the distance from the center line of the screw to the inside edge of the frame. C-clamps range from 3/4″ to 14″.
Most have a sliding cross-pin handle or a wing nut that is used to tighten the screw.