The basics

Dos and don’ts:
Here are some pointers to keep in mind when you’re clamping:

1: Don’t rely on clamps to pull together a poorly fitting joint. Glue and pressure may hold things together for a while, but in the long run the joint will fail. Plane or sand the pieces until they fit properly.

2: Before applying glue, test-fit the parts. Preadjust the clamps so they’re ready to apply pressure with just a few twists.

3: Never force a clamp or use a spanner to tighten it. If the clamp isn’t strong enough, use a bigger one or add another clamp next to it.

4: Too much clamping pressure can squeeze all the glue out of the joint and compress the wood fibres. Too little pressure can result in a glue line that is too thick and therefore weak. An even ridge of glue between clamped parts, at the top and the bottom, indicates proper pressure.

5: Leave the clamps on for the recommended length of time. Most glues specify a minimum clamping time.

Spreading pressure:
Clamp heads exert a cone-shaped area of force. To distribute pressure over a wider area (and to protect the work from damage) place wood off cuts or angle irons between the work and the clamp heads.

G-clamps

Extend-a-clamp:
Suppose you are gluing wood trim to a flat workpiece and your G-clamp can’t reach the joint because it has a shallow throat. Here’s a way to increase the clamp’s reach using only a strip of hardwood and a block of wood that’s thicker than the trim. Place the block near the edge of the workpiece, position the strip under the clamp shoe so that it spans the gap between the block and the trim, and clamp down. The strip will transfer pressure to the joint.

No more bouncing ball:
It isn’t easy to hold a curved, irregular piece tightly in a miter box. An ordinary soft rubber ball can provide a good way around this problem, Cut off a piece of the ball to create a flat area, and glue a film canister cap to the opposite side. Place the cut side of the ball against the workpiece and the clamp head in the cap. Clamp the ball and workpiece in place securely . The ball will conform to fit any shape and won’t scratch the work.

Coupled… for a job:
If a workpiece is too wide for one G-clamp to span it and you have no suitable substitute, combine two G-clamps acting against each other. This trick will work well in situations that require only light clamping pressure. Don’t try it if you need to apply heavy pressure.

On edge:
If you don’t have an edge clamp and tape isn’t suitable for the job, use shims with a G-clamp. Drive wedge-shaped shims between the edge piece and the back of the clamp until they fit snugly.

Hand screws

Jaw line-up:
Mark the handles on your hand screws to quickly set the jaws parallel. With the jaws closed and parallel, apply a narrow paint line or other mark down the centre of each hand grip. No matter how wide apart the jaws are set, if you keep the lines in the same relationship to each other, the jaws will be parallel. Keep in mind that the jaws can also be set at an angle if the job calls for it.

Working together:
Use pairs of hand screws to hold oddly placed pieces together. If you don’t have a woodworker’s vice, use a combination of hand screws, bar clamps and G-clamps to hold a workpiece for planing, sanding, chiselling or shaping. A setup like the one below will allow you to work without interference from the clamps.

Pipe clamps

No warpage here:
Here are a few tricks for gluing strips edge to edge. When you glue up boards that will form an overhanging surface, such as a table top on a pedestal, set the boards with the growth rings alternating up and down. To hold any glue-up, stagger pipe clamps above and below the workplece, adding spacer blocks to keep the clamp pressure in line with the boards. If the clamp jaws are longer than the thickness of the work, angle them so that they contact more of the work. Or place a wood dowel lengthwise on each side of the work to redirect the clamping force.

Clamping a trapeizoid:
To clamp shapes with unequal parallel sides, such as a chair seat frame, you’Il have to create right-angle clamping surfaces. Place wood off cuts against the two parallel edges. This allows the clamps to seat properly and to apply pressure at the proper angle.

Custom-made block:
Round or elliptical edge pieces, which are common on table tops, can be clamped together with the help of a block that fits snugly around the workpiece. You can also make blocks to match other unusual shapes. If you have trouble steadying the block while applying the clamp, contact glue it into place; then pull it off afterwards.

Hold the door:
Secure a door in a vertical position for planing or mortising by using pipe clamps or hand screws. Stagger the pipe clamps, alternating left and right, along the bottom edge of the door.

Makeshift clamps

Spring clamp look-alikes:
Two substitutes for a spring clamp: large battery clips from old damaged jumper leads will accept work up to about 1-1/2″ (38 mm) thick, and the spring clip on the end of a pants or skirt hanger will hold a small workpiece. The jaws of some hanger clips are padded with felt strips that will protect your work from marring.

Mousetrap technology:
You can turn a mousetrip into a strong, versatile wide-grip clamp. Prise off the bait holder and cut off the hold-down side of the base before applying the other half to the work.

Gun clamp:
A caulking gun is ideal for applying light pressure to small pieces. Place the work between lumber off cuts, and then position the assembly between the jaws of the gun. The off cuts protect the work and provide a flat surface for even pressure. To apply pressure to the work, squeeze the trigger.

Rubber-band clamps:
Sometimes clamps just don’t work well for gluing small or irregularly objects. To hold such pieces together, keep a variety of large rubber bands in your workshop.

You don’t have to jump for the cords:
Elastic cords are an ideal substitute for web clamps. Because the cords are not adjustable, keep a variety of sizes in stock. You can combine short cords to make longer ones; wrap long cords around small pieces several times or in a figure of eight.

From the garage:
An ordinary hose clamp, like those found on car radiator hoses, is just right for clamping a cracked or split wooden leg or spindle. This clamp is inexpensive, comes in a variety of sizes and provides good uniform pressure when tightened. Slip a piece of cloth or vinyl under the band to prevent marring.

Big mouth:
For a longer reach, you can extend the jaws on a pipe clamp. In two wood blocks, drill holes large enough for the pipe to fit through; then carve out jaws to concentrate the pressure. Use stout rubber bands to secure the blocks to the clamp heads, and slip the assemblies onto the pipe.

Home-made clamps

Bag it:
When you need to join irregular shapes, hold them together with a sandbag. For small fragile items, use a small plastic bag filled with sand. Use larger sandfilled bags for big items. For outdoor projects, try plastic bags or containers filled with water from a hose.

Tourniquet a frame:
Holding mitered corner pieces together is simple with a tourniquet clamp. Make four L-shaped corner blocks. Rout or chisel grooves on the outer edges to guide the string, and make vertical grooves at the inside corners to allow excess glue to escape. Place the blocks in position and run string around the perimeter. To tighten the string, wrap a dowel or stick in the string and twist it.

Holding a scarf:
Here’s an easy way to spread pressure evenly along a scarf joint. When you cut off the ends of the work, save the triangular off cuts. When you’re ready to clamp, place the off cuts between the work and the clamp as shown.

Edgy situation:
If you run out of clamps in the middle of a project, you can make your own out of lumber off cuts. Screw one block to each end of a length of board that’s slightly longer than the workpiece. Attach each block with only one screw so that it will pivot into alignment. Cut two wedgeshaped pieces of wood, and drive them between one of the blocks and the project for a tight hold.

H-frame:
An H-frame jig is ideal for edge-gluing two or more boards (the long legs of the frame apply equal pressure along the boards). The jig is easy to make out of scrap lumber and 3/4″ (19 mm) plywood; to reduce the weight of the frame, you can trim the plywood a little. Create clamping pressure by driving a pair of wedges between the straightedge and the jig.

Extending the top:
By building a larger top for your portable workbench, you can use it to clamp large objects. Make the new top out of 3/4″ (19 mm) plywood and four pieces of 2″ x 2″ (50 mm x 50 mm) lumber. One side of the new top should be slightly wider than the underlying side of the old top; the other side should be about twice as wide Attach both sides of the new top to the original top with screws.