Clamping cauls aren't the most amazing shop project ever, I will admit. But they are a small but important part of having an operating workshop.

Cauls: a nice small project

While cleaning up I ended up with (not surprisingly) a whole bunch of smallish Baltic birch offcuts. This reminded me of a few clamping operations over the past few months when I wished I had some clamping cauls that weren’t covered in glue and were a bit longer. A tiny little light bulb went off in my head and I got to work.

Fifteen minutes later I had tossed out a bunch of old cauls and made a few different sizes of brand-new Baltic birch cauls. They all had their edges sanded smooth and were sitting very neatly on the shelf. It was a nice feeling to be able to finish a job in about 15 minutes. I even had the clarity and forethought to rearrange the cauls so the ones I use most are closest, while the ones I seldom use are a bit farther away. Wow, was I in the zone that day.

Interestingly, the cauls I use less often are cauls I enjoy using the most. I have some slightly curved cauls (of a few different radii) that are offcuts of curved bending forms I’ve trimmed to about 2″ long. They’re great for bent lamination work and other times when I work with curves. I also have notched cauls that are good for a wide variety of weird and wonderful situations. Using them on the outside of 90° corners to provide a better clamping surface is one option. I’ve also used them on outside corners that aren’t 90°. Another time I use these cauls is when I’m positioning the cauls across a glue line and don’t want to glue the caul to the project. The notch goes right over the glue line. Some of these notched cauls have dowels running across the grain, as when you apply clamping pressure in some situations they tend to split. The dowels tend to keep the cauls together pretty well.

Using cauls

In case you’re not quite sure what I use all these cauls for, they’re usually used during a glue-up to protect the workpieces and to disperse clamping pressure over a wider area. I often make them out of solid wood, as it’s pretty durable, rigid and comes in thicknesses larger than 3/4″, but since I had a bunch of Baltic birch plywood pieces kicking around I made a few sizes, rather than toss them in the garbage.

I may use cauls on their edges, as that approach is best for dispersing clamping pressure, but a 3/4″ caul can sometimes add problems to an already tricky glue-up. Thinner cauls have the tendency to not sit flat against the workpiece, which can cause a host of problems. Every situation is different, which is why I have so many shapes and sizes nearby. Although you can’t see them in the photos, I have many cauls between 24″ and 60″ in length, which are great for clamping up larger panels or cabinets.

Next time you have a few offcuts, cut them to a manageable size, ease their edges and give them a dedicated shelf to call home. Before you know it you’ll have a helpful collection of clamping cauls you’ll reach for regularly.