Popular Woodworking 2002-06 № 128, страница 50

My first glimpse of a Bessey K-body clamp was on PBS's "The New Yankee Workshop." Like many viewers, I said: "I need some of those!" A few phone calls later, we were well on our way to populating the Popular Woodworking shop with our new-found loves.

That was about six years ago, and we've been surprised that there's been little competition in this category. Then, last year, Gross Stabil introduced an improved version of its parallel-jaw clamp, and Jorgensen introduced a new line of this same style. Both are aimed at Bessey. With three different parallel-jaw clamps in stores, we decided it was time to put 'em all in the shop to see how they stacked up.

Why Buy These Clamps?

First, what's a parallel-jaw clamp? Unlike traditional bar or pipe clamps, the parallel-jaw clamp has a flat and wide jaw surface that exerts even pressure along the length of the jaw. The even pressure starts all the way at the back of the jaw, against the bar, and continues out to the end of

Parallel-jaw

CLAMPS

These clamps aren't cheap, so you should make sure you're getting the most for your money.

by David Thiel

Comments or questions? Contact David at 513-531-2690 ext. 255 or david.thiel@fwpubs.com.

the jaw mouth. This makes gluing up flat panels a cinch. You can rest the panel on the bar, providing a flat, supported glue-up surface. It also means you can glue up a box and put even pressure along the edge of the joint, rather than at just one point.

Another advantage of all these clamps is they rest flat on your assembly table as you glue up a panel - no rolling or tipping. And once your panel is clamped, you

can set the whole thing on end, and your glue-up will stand upright on the outside edge of the jaw. This frees up space on your assembly bench and allows you to keep working.

Details of the Test

To test the clamps, we simply put them to use. You may note that while we've included the reported clamping pressure for each clamp, we haven't compared or discussed this feature in the individual comments. Truth be told, too much clamping pressure will starve a glue joint. Suffice to say that all three of the models have more than enough pressure to perform any clamping task.

Our first clamping test was gluing up a simple, two-piece flat panel. The pieces were positioned to the inside of the jaws, lying on the bar. We looked for flex in the bars, as well as bowing in the panels during this test.

Next, we glued-up similar flat panels with the pieces lifted off the bar, held at the very tips of the jaws, unsupported by the bar. We used this test to look for bowing in the panel, and for any gapping at the joint caused by out-of-parallel pressure.

For a third glue-up, we cut two ¹/2"-thick x 3" x 8" pieces of wood and clamped them end-to-end with the width of the pieces running the length of the jaws. We again checked for bowing and gapping at the glue joint.

One last test concerned durability. We dropped the clamps three times from workbench height to see if any damage occurred to the jaws. Finally, to test the durability in extreme shop conditions (or compressing years of use into a few minutes) we struck the most vulnerable corners of each jaw with an 18 oz. hammer three times with mixed results.

48 Popular Woodworking June 2002