Clamping cauls have probably been around as long as woodworking, but they seem to come in and out of favor. New woodworking tools, attachments, jigs, and techniques come along on old ways are often forgotten. But not everyone has the latest tools, jigs, and techniques, in fact many, especially in woodworking, like doing things the traditional way and what could be more traditional than Clamping Cauls ....
Watch it on Youtube: https://youtu.be/OZ53CF7Gb1s
At one time, much earlier in my woodworking career, I used nothing but clamping cauls for all sorts of assembly and glue-up jobs. They worked great then and they still work great, I just don't use them much anymore, have fallen to another technique that I like, and that works well for me, the Dowelmax systems ... but that doesn't mean I have abandoned clamping cauls, they are still invaluable for certain jobs ...
There are many different kinds of clamping cauls from the very basic, which is simply a couple of straight, even boards that can be clamped together to help align boards, cabinets or whatever project is being constructed, to versions that are tapered to the ends, so that when pressure is applied to the ends, if focuses more clamping pressure on the middle. I also have a pair of "I" Beam cauls that I use for, among other things, heavy-duty clamping because they are so constructed that when pressure is applied to the ends, they are so rigid, that same pressure is applied evenly along the whole clamp length. I use these more for clamping cabinetry that I am making where sometimes my joints are a bit tighter than they need to be.
Making cauls is easy, and in fact, the easiest way of making cauls is to go to the lumber store and look for construction grade lumber that already has a significant bow in it. If you are lucky, they may even give a discount to take away their bent wood.
Making your own cauls is nearly as easy, but you also have more control in size and shape. I like the ones that have a tapered end and are a bit thicker in the middle. They are easy to use and work well. I have found the thickness that works best for me is about 3/4 inch deep and about 1.5 inches wide. In the video I show who to bend some thin wood to get the slop on the ends, then rough cut on a bandsaw and finally clean up the cut using a hand plane.
These slopped cauls can be used together or with opposing flat cauls ... it all depends what you need and what works best for your situation.
The only other thing to be careful of is that when gluing and using cauls, there is always a risk that they can adhere to your glue-up. There are many different ways of preventing this from using wax paper to various different sheet plastics to prevent the glue from touching the cauls. In the past, I have also used paraffin wax to coat my cauls, but I'm sure a good past wax would work well too. Even painting the cauls with varnish is good ways of preserving them, and helping to ensure they stay glue free.
If you have never used cauls during glue ups and you are challenged like I was, give these a try, they saved me time and effort for many, many years ....
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Copyright Colin Knecht