Gary writes, “Awesome job on the podcasts!! Had a question on the cauls used for the cutting boards. Are they flat, or do you put a curve. If curved, what’s the best way?”
And here’s my reply, “Hi Gary. The cauls I used in the video were simple and straight. The only time I use curved cauls is on a long glueup where I cant get a clamp in the middle. Fortunately, the small cutting board allowed me to place a clamp directly in the middle.
If you need to make a curved caul, I think the easiest and safest methods are with a belt sander or with a hand plane. To make it, simply mark the center of the caul, and draw straight lines out to each end, representing the material you want to remove. You don’t really need more than 1/8″ difference between the center and the edges. On longer cauls you may want to go as far as 1/4″. Once you have your lines drawn, just clamp up the piece of wood in your bench and start planing or sanding to the line. Once I get close to the line, I like to smooth everything out by carefully passing the caul over the jointer, one half at a time. Also note that I usually use 2×4 lumber for my cauls since they’re cheap, accessible, and also relatively soft and non-marring.”
Here is an article that pretty much says the same thing I said above, but with a picture:
Fine Woodworking Article