Most gluing in woodworking is "edge gluing," where you glue edges together to make something like a table top. I'll be doing plenty of edge gluing on this table, but first, I need to do a bunch of "face gluing," which is done to make thicker wood. Lynne's tabletop will be around 1.5" thick, so I need to face glue a bunch of 3/4" boards together.
After applying the glue to both faces, trying to keep them aligned while clamping is a pain because the two pieces tend to slide all over the place. So I had a brilliant idea of putting a screw through both boards on each end before clamping. Something like this:
I glued the boards up and after a couple hours took the clamps off to find a new, badly twisted board. Duh, if I fix the two ends, and if there's even the slighted amount of bow in one of the boards, then clamping will cause a lot of stress in the boards, leading to twist. Argh.
It's a little depressing that it took a couple of weeks for me to realize this. Thankfully I didn't glue any more boards in the meantime (I took some time to build a sled for my planer to simplify taking out twist, but more on that later). After considerable time and thought, I finally started gluing up boards again yesterday. I did two things differently. The first is that I clamped the boards to my flat table. Like this.
The second change is that, instead of screwing the boards together at both ends and then clamping, I screwed them together on one end, and then added clamps moving from one end to the other. Like so:
(And yes, that is every clamp I own.)
So, the result? A beautiful, flat, double-thick board. Woot!