One of the woodworking tasks with which I struggle mightily is hand-planing the twist entirely out of thinner stock. I have found, though, that careful alignment during the glue-up is one way to manage (and maybe even eliminate) any remaining twist in a thinner board that is part of a larger panel (like a table top). This won’t work for boards that are majorly out of wind, but there is a very simple jig you can make from scrap to perfectly align two boards in a glued butt joint.
The alignment cauls pictured above are 1″ thick slices of red oak 2×4, with a 1/2″ x 1″ groove routed in them. The exact size isn’t critical, but you want them to be wide enough for a decent sized groove and thick enough to easily take a clamp. I recommend routing the groove first, then cutting the slices and truing the faces with the groove over some sandpaper on a flat surface.
The most important part, before any gluing up, is to make sure the two boards are planed as flat as you can get them and thicknessed to the exact same thickness (the thickness is the critical part). Once that is done, you clamp two cauls, opposite each other, to straddle the glue joint and perfectly align the outside edges of the boards. You use four cauls per glue joint (two on each end, pictured below). Once the glue dries, just dress the seams.
When doing the dry run for the angled-leg side table glue up, I noticed there was about 1/32″ twist in each of the boards. It would have been no problem to skip the cauls and just level the seams after glueup, but I had them handy and the boards are already thin enough (5/8″ after thicknessing) without any more dressing.
You should always try and get as much twist out of the boards as you can, but in a pinch (nailed it!), these alignment cauls will get the job done.
I will post pictures on twitter of the finished table, once I figure out how to attach the top.
I usually use spring clamps for this. I think your idea is better 🙂
I have done the same, but then the glue gets all over the pads on the clamp. The routed groove that straddles the glue line solves the problem.
Also, I think I learned this trick from one of George Vondriska’s videos over at http://www.wwgoa.com
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Exactly. Thanks for the link, I’ll check that out.
It’s a powertool-based site, so not all that relevant to me anymore. But there is some good stuff on there for all woodworkers, especially relating to finishing, etc