Beginner's Guide to Clamps

Woodworkers need clamps for an endless variety of tasks: securing project parts to the bench as they work on them, serving as a third hand, coaxing reluctant parts together, holding assemblies in place during a dry-fit and while glue dries…well, again, the list is endless.

That's why you find such a large variety of clamp styles and sizes available. Don't fret; you don't need them all (yet). Start with our recommendations for building up an initial clamp collection. You'll discover which ones you use most often, and which types you wish you had, so you can expand your selections accordingly.

These clamps have feet or flat bottoms so they stand in place on a bench as you place project parts on them, such as when gluing up a panel.

With pipe clamps, you really only purchase the fixtures that fit onto ¹⁄₂ " or ³⁄₄ " pipes that you buy separately. Even so, the combined cost remains the cheapest option for clamps with a long reach. Buying your own pipe means you can make clamps any length you like. (Have the ends threaded, if they aren't already.) The fixed jaw of the clamp fixture threads on one end, and the movable jaw slides along the pipe. With couplers, you can join pipes to make even longer clamps [Photo A].

The shallow jaws work well for panel glue-ups and carcase assembly, but limit the reach on thick workpieces or into the interior of a wide assembly. The beefy Acme threads of the fixed jaw apply lots of pressure, but even ³⁄₄ " pipe can flex after too many twists of the handle. On the downside, long clamps weigh a lot, and wet glue can react with the pipe and wood, leaving black marks on your assembly.

Our recommendation: Start with four sets of clamp fixtures, four 2' pipes, two 4' pipes, and three couplers.

With a jaw depth about the same as that of pipe clamps, the biggest advantages of aluminum bar clamps are their light weight­—about half of comparable pipe clamps­—and that glue contact won't discolor the wood. They provide sufficient pressure for most panel glue-ups and carcase assemblies [Photo B], but will flex under heavy pressure.

Our recommendation: Consider buying a few in longer lengths if you find similar-length pipe clamps cumbersome.

Deep jaws reach farther, and even provide enough capacity for crossing clamps perpendicular to each other [Photo C]. The jaws stay parallel under heavy pressure, and the beefy bars resist bowing, keeping panels flat and pressure even. If you need to move a clamped assembly out of the way, simply stand the clamps on end [Photo D]. On some models, reversing one jaw creates a spreader for pushing pieces apart [Photo E]. As with pipe clamps, the heavy-duty performance reflect in their weight (and price).

Our recommendation: Step up to these after you determine if they'll be useful to your style of work.

Woodworking involves more than gluing up panels and cabinets. For the everyday tasks that require temporarily securing something to something else, these clamps come through in the clutch.

These workhorses prove indispensable for securing items to your bench [Photo F], clamping drawer and box glue-ups [Photo G], and countless other jobs. The typical 4" jaw depth works for most applications, but available deeper jaws prove useful, too. The twisting action of the handle and the swivel head can shift parts out of position as you tighten the clamp, so when possible, place the movable jaw against the stationary part of an assembly.

Our recommendation: Start with four each in 6" and 18" lengths. You'll soon be adding more in various sizes, and the moderate price makes it easy to do so.

When you have only one hand free, use it on the squeeze trigger that advances the jaw of a one-hand clamp [Photo H]. Your grip strength limits pressure (our tests show about 180 psi on average), but with lighter-weight bars than F-clamps, you won't use these for your most pressing jobs (sorry). Some sport a reversible jaw to create a spreader; others link together to make two clamps function as a longer one [Photo I].

Our recommendation: Buy a couple of 6" and a couple of 12".

Kind of like the last kid called for sides in PE class, these clamps don't take center stage, but often surprise you with their usefulness.

A light coat of wax on the jaws prevents glue from adhering.

These apply a fixed amount of light pressure concentrated at the pads at the tips of their jaws. A squeeze opens them for positioning. Spring strength varies among types, sizes, and manufacturers, so give them a test squeeze to evaluate clamping pressure before buying. Use one to secure a stopblock to a fence [ Photo J], hold a protective paper covering to your bench, or keep a ruler in position while you make marks along it.

Our recommendation: No need to overdo these; two each in 2", 4", and 6" will take care of most jobs.

The deep reach and the ability to cant the jaws out of parallel make handscrews a valuable part of a clamp collection. Because the dual screws turn independently, you can twist just one, using the other as a fulcrum to multiply pressure at the ends of the clamp. And you can grip items in either end [ Photo K]. The wood jaws are less likely to mar workpieces, and you can easily modify them to hold non-square items [Photo L].

Our recommendation: Get one each in 6", 8", and 12" sizes.

Wait to buy these clamps until you have a specific need for them.

Wrap its webbed strap around a glue-up to hold corners together, such as when assembling a box or drawer. Some have blocks with pivoting jaws that protect delicate mitered corners and can accommodate corners other than 90° [Photo M]. The blocks also lift the strap off the workpiece so the strap doesn't get glued in place or fouled by squeeze-out. Tighten a screw or a ratcheting mechanism to apply pressure.

These often serve as a much-needed third hand, aligning perpendicular pieces as you twist the handle to apply clamping pressure. If you see frame-making in your future, a set of four makes life much easier [Photo N].

For the money, nothing beats C-clamps for applying pressure [Photo O]. The crossbar in the screw handle, the hefty threads, and the beefy iron body make these clamps overkill for most jobs. However, the long threaded rod provides a large capacity (after much spinning of the screw).