Using Cauls and Playing Cards for Even Clamp Pressure

Assembling this project offers a variety of challenges. One is that because I'm working with a solid wood case side here, I find that when I put my shelves onto their biscuit joints, they touch on the outside, and it's just a little bit gappy in the middle. I wanna make sure that that gap closes. So the answer to this is gonna be a caul. A caul is simply a piece of wood that's gonna span across the bottom so that when I put clamp pressure on this side and clamp pressure on this side, it applies pressure to the case side and helps flatten it against the end of my shelf.

Now, the problem I have sometimes with cauls is that as they come up against the case side in this case, they bend with it. So what we wanna do is add a little extra insurance to make sure that I really do close the seam here in the center. And that's the deal with the playing cards. So we're not messing around here playing cards while we're not shooting video. They're here for a reason.

What I'm gonna do is put two of these cards, a queen and a four, in the middle of the caul. Then the caul's gonna come underneath here once I have the shelf in place. And when I put clamp pressure on it, what happens is that the thickness of the cards force it to make contact here in the middle first. Close that part of the joint. I continue to apply clamp pressure.

That'll close the front and the back. Make sure it's nice and solid all the way across. So it's really a good card trick. So here's how this works. We're gonna get glue into our biscuit slots.

Now, this is gonna lead to some squeeze-out. You can probably see squeeze-out I've got on the other shelves. That's okay 'cause what I'm gonna do is allow that squeeze-out to dry to a point where it's just a little bit rubbery, and then I'm gonna come back and slice it off with a nice sharp chisel. Gotta get nice uniform spacing from the front. I'm using a piece of brass bar stock to make sure my reveal is the same on every shelf.

Now, this is the part where being an octopus would be handy 'cause I wish I had a few more hands. But we'll get the caul under there with the cards in the middle. The clamp on here. For this project, the shelves go on at three degrees. It's a tapered display case.

Make sure the caul is still under that shelf. Boy, looking at it from this side, that seam is really closed. Now, what I need to do is check my angle. That's a three degree gauge block. Little bit of clamp adjusting here.

There we go. So with the addition of my cauling cards to the caul, it closed that seam in the middle. It's nice and tight. Those cards go a long way toward increasing the quality of the glue join here so I have a nice tight seam all the way across. Really looks great.

Try this trick in your shop. It's gonna really help you close these joints up.