Why does nobody talk about clamping cauls for panel glue-ups

I spent five years building cabinets and always fought with panel gaps after glue-ups, thinking I just wasn't pressing hard enough. Last week I was helping a buddy at his shop and he handed me a set of clamping cauls he made from scrap 2x4s. We used them on a walnut tabletop and the joints came out perfectly flat with zero lippage. It hit me that every video I watched showed people struggling with clamps, but nobody mentioned these simple blocks. Now I feel like an idiot for not figuring this out sooner. Has anyone else had a basic shop trick completely change their workflow?

3 comments

3 Comments

shane_hayes11d ago

Man, clamping cauls are one of those things that seem so obvious once you see them but nobody tells you about them. I feel like every beginner video focuses on how many clamps you need or how tight to crank them, but never on the actual geometry of keeping panels flat. So here's what I'm wondering: did your buddy's cauls have a specific curve or camber on the clamping face, or were they just dead flat? Because I've seen some guys argue you need a slight bow in the middle (like 1/16") to really squeeze out the lippage at the joints.

gray87511d ago

I built a set of cauls last year for a walnut dining table top and went with a slight curve. I planed a 1/16" gap in the middle on a 4 foot caul. Worked great for pulling the joints tight without bowing the whole panel. Dead flat cauls just seem to let the middle of the joint stay open while the ends squeeze down. I've heard some guys say you need even more camber for thicker stock but 1/16" was plenty for 4/4 lumber. Just make sure your cauls are thick enough so they dont flex when you crank the clamps. I used 1x4 poplar and it held up fine.

jakeb819d ago

Heard an old timer once say he used a car jack between his cauls to push the panel up into the clamps from underneath, rigged up some plywood and scrap 2x4s into a little cradle. Sounded wild but he swore it got the joints tighter than anything else he tried. Never had the guts to try it myself but I think about it every time I'm fighting with a glue-up.