One more Caul Question

[Sean Troy]

Any reason I can't use a 2x4 for cauls? Can they be 2.5 inches tall after planing?

[Sebastien La Madeleine]

They can, but then the flexing won't be as easy to make happen. If you're working with soft woods, you'll most likely dent it before your cauls are flat.

One way around that would be to put a very shallow curve in them (about 1/32nd per foot). That way, over a 4 foot caul, you'd only have about 1/8 of compression. I make them 1.75x1.75 in maple and I give them about 1/8 per foot of curve...

I did not come up with the measurements though:
http://www.leevalley.com/US/wood/page.aspx?p=67309&cat=1,43838

[Mike Henderson]

I've made cauls from 2x4's and found they work well. Here's (http://www.mikes-woodwork.com/Cauls.htm)a few web pages of what I did.

I respectfully disagree with Sebastien about flexing. 2x4's will flex quite a bit, but flexing is not necessary. If you had a material that was absolutely stiff (didn't flex at all), you could use it as a caul with no curvature. What you're after is matching the curvature to the amount of flex in the material and the amount of pressure you want in the center of the applied cauls.

The good news is that it's not critical. As long as you get pressure in the center of the applied cauls, it'll probably work. It's nice to achieve even pressure all along the caul but if you don't, they still work (unless you're WAY out).

Mike

[The caul in the first picture on my web pages is one I made as an I-beam. Those are pretty stiff. I use them differently so they're made flat - no curvature at all.]

[Sean Troy]

Once again, great information, thanks

[Chris Padilla]

Pick up some nasty looking 2x4s from the local borg and toss 'em out in the sun. In 24 hours, you'll have perfect cauls to use! :)

Check out Bow Clamps for further ideas.

[Sebastien La Madeleine]

Ahh sorry for my misunderstanding, I tought you meant 2x4 hardwood, but pine 2x4 will flex indeed. I would be worried about gum and sap running out though... I prefer to work with hardwoods...