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The Bessey DKX DuoKlamp Extender is an ingenious accessory that gives you far more reach in both clamping and spreading modes than you would have imagined.
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Bessey DKX DuoKlamp Extender

A DuoKlamp accessory with big reach capacity

Text, photos and video by Tom Hintz

Posted - 5-4-2009

As if the Bessey DuoKlamp was not very handy in its own right, Bessey came up with their DKX DuoKlamp Extender that boosts its clamping and spreading capacity in a big way. And, being Bessey, designing this very cool accessory so it lives up to their traditions of maximum function and durability was second nature.

Bar Basics

The bars have the familiar Bessey hourglass shape because when it is made this well it is tough and very rigid.
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The Bessey DKX DuoKlamp Extender is built around a pair of tough steel bars. Not surprisingly, Bessey employed the familiar hourglass shape developed and manufactured in their German facilities that makes them tough and surprisingly rigid. Each bar is a bit over 39"-long, 3/4"-tall and 1/4"-thick at the top and bottom.

The bars are designed so that the jaws are mounted to one and allow the other bar to pass through. This clever bypass configuration gives the Bessey DKX DuoKlamp Extender a clamping range of 6" to 65" and a spreading capacity of 7.5" to 70". The rugged design means that you can apply up to 260 LBS of force in clamping or spreading modes without fear using a Bessey DuoKlamp.

Unique Jaws

The fixed jaws are secured with a finger-operated knob (left) that makes reversing them for spreading fast and tool free. Whether in clamping or spreading mode (right) the jaws remain solid.
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The Bessey DKX DuoKlamp Extender features jaws made from a high-tech composite material that is both very strong and resistant to common materials used in the woodworking environment. Though very light, all four jaws are designed to be rigid and uniquely compatible with the Bessey DuoKlamp.

The fixed jaws at the outer ends of the bars have a clamping surface that is 3-3/8"-tall and 1-1/4"-wide. Bessey includes slip-on jaw covers on these faces that help prevent marking of the wood and make it easier to remove glue transfer.

The bars have threaded holes in their ends that accept the finger-operated knobs, which secure the fixed jaws. This knob and the design of the fixed jaws make converting the Bessey DKX DuoKlamp Extender from clamping to spreading modes fast, easy and tool free. Just remove the knobs and jaws, reverse and slide the jaws onto the end of the other bar and replace the knobs. That is the entire process. Returning to clamping mode is just as easy.

Pressure Jaws

A considerable amount of the Bessey DKX DuoKlamp Extender engineering was expended on the pressure jaws. Everything from the shape of the jaws themselves to the trick design of their locking plates have large roles in making the Bessey DKX DuoKlamp Extender work.

The pressure jaws have a unique shape (left) that accepts the Bessey DuoKlamp, holds it in place and provides surfaces that match up to its pads. The locking plates (right) are specially made so they grip one bar and let the opposing bar slide freely. Very simple but it works reliably. Whether in clamping or spreading mode, these pressure jaws never change in how they work. The DuoKlamp always squeezes as in the photo (left) above.
Click images to enlarge

When you first look at the pressure jaws, it looks like they wouldn't work. A tapered face with a stiffening ridge down the center has been designed for clearance rather than as a place for the Bessey DuoKlamp to be applied. The real clamping face is just below that. A notch at the top of the pressure jaws accepts the bar of the Bessey DuoKlamp, holding it steady on the Bessey DKX DuoKlamp Extender so you can more easily apply pressure with one hand.

The locking plates at the heart of the pressure jaws work very much like the ones we have used on pipe clamps for years. However, there is an ingenious difference at their center that makes the Bessey DKX DuoKlamp Extender easy to use and very dependable. The hole through which the bars pass is shaped so that the plates grip only one of the bars. That allows the "unlocked" bar to move freely so that force from the Bessey DuoKlamp is applied to the fixed jaws at the ends of the bars. This plate design also makes it easy to reposition the pressure jaws individually.

In the Shop

Video Tour

Using the Bessey DKX DuoKlamp Extender is remarkably simple. Adjust the size using the pressure jaws, placing them within the clamping range of your Bessey DuoKlamp. It really is that simple. The notch in the pressure jaws makes setting the Bessey DuoKlamp in place very easy and frees your other hand to hold the assembly in place while pressure is applied.

Despite the 65" reach the Bessey DKX DuoKlamp Extender resists flex remarkably well. I normally don't feel the need to clamp anything "to death" but did give the Bessey DuoKlamp a couple harder than normal (for me) squeezes to see how the Bessey DKX DuoKlamp Extender dealt with it. As it turns out, they need not fear me or the pressures I can generate. They hold the wood firmly, don't slip, don't mark the wood and do everything you would expect of a clamp.


The Bessey DKX DuoKlamp Extenders are ingenious accessories that can make clamping up longer projects by yourself much easier. Their compatibility with the Bessey DuoKlamp simplifies that process even more and can save you considerable sums of money over buying individual long clamps.

With a street price of just $24.99 each (5-1-2009) you can extend the reach of several of your Bessey DuoKlamps (and your clamping capabilities) very reasonably. Plus, you still have the handy capabilities of the Bessey DuoKlamp. Sounds like a winner to me!

Visit the Bessey web site - Click Here

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