Sometimes you need to clamp a long board to a wide board. This sometimes means you aren’t clamping along the edge, so you’re clamps don’t reach acros the entire long board.
Here’s what I mean:
And clamping at each end is not good enough to apply sufficient pressure at the middle, especially when the long board has a slight bow to it.
Here I’ve clamped the ends and this card freely slides under a section of the board where it’s bowed:
So here I’m going to show you how to deal with long boards like this, so you can easily apply good clamping pressure along the entire board.
Get a piece of wood roughly the same length as the board you’re clamping.
We’ll call this the Clamping Caul.
It doesn’t need to be exact, and the width should be at least 1″.
You’ll also need a 1/4″ thick block of wood to act as a spacer.
Apply the glue and lay your board to be clamped in place.
Then put your spacer block on the high point of the board (or the middle if there is no ‘high point’).
Then set your Clamping Caul on top of that, on it’s edge.
Then clamp the ends down tight. The caul will bow and apply good pressure down on the spacer block.
And that’s it.
With minimal setup and a couple pieces of scrap wood, you’ve got yourself a good glue-up.