C-Clamps and F-Clamps: How They Differ & Why You Need Them

The mechanisms and strength of these clamps can differ slightly, but each one can help across a broad range of project types.

by J. Keeler Johnson
PHOTO: J. Keeler Johnson

If you’re experienced with woodworking or metalworking, then you probably know how useful clamps can be to hold items together and keep things in place. But if you’re relatively new to DIY farming projects and are still building up your tool collection, today I’ll tell you about the benefits of these small, simple, and highly useful tools.

First, the terminology. “Clamp” is really too vague. I refer to adjustable clamps of varying sizes designed to exert a squeezing pressure between two flat surfaces. A “C-clamp” (also called a G-clamp) is shaped like the letter C and is smaller than an “F-clamp” (also known as a bar clamp), which—not surprisingly—more closely resembles the letter F. The F-clamp opens significantly wider than a C-clamp, so you can use it with larger objects.

C-clamps and F-clamps share the same principles and are simple to use. Each has a way to adjust the size of the opening between two ends of the clamp, similar to the mechanism of a crescent wrench. This is often a screw you can tighten to exert a powerful grip on objects, although some F-clamps tighten by repeatedly squeezing a trigger and loosen by a single release lever. This makes them faster and easier to use, although the trigger mechanism sometimes doesn’t tighten as thoroughly as those of screw-type clamps.

Through the years, I’ve put both types of clamps to use in many situations. Recently, I needed to bore a series of holes through two pieces of wood so that each hole in one piece lined up exactly with the hole on the other. I stacked the two pieces together, clamped them down tightly and drilled through both at once, ensuring that the holes were in the same location on each board.

Another time I used a clamp to solve a rather tricky problem with a yard hydrant. A small brass cylinder had been slightly squeezed out of shape (brass is a very soft metal) to the point that it no longer fit smoothly within the casing of the hydrant. Ultimately, I clamped the cylinder to the wooden end of a table so that the damaged section extended out over the end of the table, and I used a pair of locking pliers to carefully grind away the offending bits of metal until the cylinder was perfectly round again and could slide easily back into its casing. Having the cylinder locked into place was critical; if I’d just held it in my hand, it would have been impossible to keep it steady enough to effectively grind away the roughened metal on the damaged end.

These two very different examples demonstrate my point: Whether you’re working with wood, metal or another material, C-clamps and F-clamps provide essential help in a many situations by holding items together. They’re valuable enough that I have at least a dozen of varying types on hand for my projects.

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If you’re experienced with C-clamps and F-clamps, what are some of the projects that you’ve used them for?

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