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NOTE: cauls are made from w-square hardwood blanks

WITH ONE EDGE SLIGHTLY CURVED V______

using cauls to

Put on the

Squeeze

top view

size cauls to extend slightly past workpiece

I've read about using cauls as a way to get better results when assembling a project or gluing up a panel. What exactly are cauls and how do I use them?

Ben Nelson West Des Moines, IA

^ arrow points to curved edge

DIYIDER

NOTE! caul shown in position prior to adding clamps

, -SIDE

t -■„ - ....

shape the caul. But you can sand the taper just as easily.

Now, a Vi6" isn't that much of a curve. And when you're in a hurry gluing up a project, it can be hard to tell which edge to place against the workpiece. So it's a good idea to mark which way the caul goes with an arrow for easy identification.

Flat Panels Too. Cauls also work great for gluing up flat panels. In this case, applying pressure at the center of the panel isn't necessary, so I just use cauls that are straight, without any taper or curve.

What's more important is keeping the panel flat while you clamp the boards together. The trick is to sandwich the boards between cauls to form a flat panel. Then you can add the clamps, like you see in the photo at left.

Finally, when you glue up a panel, you'll want to apply a couple coats of wax to your cauls (or packing tape, as in the inset photo). This way, you won't have to worry about gluing the cauls in place. &

Cauls are really just a fancy name for a set of clamping bars that help you glue up a cabinet assembly or solid wood panel more accurately.

Let's say you're gluing up a case with a shelf or divider located several inches in from the top or bottom. Without specialized clamps, it's almost impossible to apply pressure to the center of the side panel. Instead of pulling the panel tight against the

edge of the shelf or divider, the side will bulge out slightly.

Cauls Solve the Problem. To solve this problem, you can use a set of cauls to apply pressure evenly across the sides (photo above). For this to work, the cauls are shaped with a slight curve or taper (detail drawing). When the clamps are tightened, pressure is applied to the center of the panel first, pulling it in tight.

Making Cauls. Making a caul isn't difficult. Start by cutting a length of stock (I like to use lW'-square maple) that will span your assembly or panel. Then just make a gentle curve along one edge.

How much? In general, I've found that tapering the caul Vie' or so works out just about right, as you can see in the drawing above. I like to use a hand plane to

50 ShopNotes No. 81