Popular Woodworking 2007-02 № 160, страница 61

Adjusting a handscrew: The hand that holds the center handle remains stationary. You move the jaws by cranking the lower handle over the center handle. Clockwise opens the jaws. Counterclockwise closes them.

until only the adjacent surfaces of the jaws begin to tighten on the work. Then, turn the rear handle, bringing the jaws back into parallel and evening out the pressure along the jaw's entire length.

A handscrew is a powerful clamp. How much you tighten the jaws will control the pressure. If the work is delicate, an over-tightened handscrew can damage it. I have found that over tightening can also starve a glue joint by squeezing out all the adhesive.

If the job requires multiple handscrews, put them in place one at a time, applying enough pressure to hold the clamps in place. When they are all secure, go back and tighten them uniformly.

Sometimes you do not want even pressure, but instead need to apply force to a precise point. In that case, adjust the handscrew to the approximate setting. Then, placing the ends of the jaws where you want to apply the pressure, turn the rear screw. This will close the jaws out of parallel so that all the force is applied to the tips of the jaws.

To clamp an irregular shape such as a taper, open or close the jaws to the approximate shape. Then, you will have to fit the jaws to the work by changing their angle as required. This is trial and error. Increase or decrease the

angle with the rear screw and use the center screw to change the distance between the jaws.

Handscrews are very versatile and as you become more acquainted with them you find countless ways to use them around the shop. Held in a bench vise, a handscrew can work as an upright vise for carving or close work. A handscrew applied to a piece of thin stock will reduce the danger of splitting. I do this when mortising by hand. However, I clamp a second handscrew to the first to hold the setup securely on the benchtop. You can use a similar arrangement to create a make-do bench vise. Handscrews are also good for holding j igs, fixtures and stop blocks.

A well-equipped shop will have numerous handscrews. I have about three dozen, mostly 12", and they take up a lot of space. I store mine in three ways. Some I hang on a wall. I drilled holes into a 2 x 4 cleat that is lagged to the shop wall. The holes are angled slightly upward and receive lengths of ³/4" dowel. Each dowel will hold three clamps. I have another cleat to which I simply clamp a row of handscrews. I also have a clamp stand. This is a wooden column on an X base. I pile the handscrews on it by passing the post between the metal spindles. PW

When you want a handscrew to apply pressure evenly along the jaws, adjust the jaws so they are slightly out of parallel with the tips more open. Tighten the center spindle until the jaws just begin to pinch adjacent to the center spindle. Then, bring the jaws into parallel by tightening the rear spindle. This will create even pressure along the jaws' reach.

Handscrews can apply significant force at their tips. First get the jaws to slightly pinch the work (above). Then, when the handscrew is in position, turn the rear handle to apply force at the tips alone.

Handscrews can be used in tandem to hold work for planing or chiseling. They can, in a pinch, even substitute for a bench vise.

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Popular Woodworking February 2007