glue ups

[Dave Macy]

I'm beyond frustrated. Keep in mind I'm 18 and learning, but I did my first walnut glue up and the darn thing bowed really bad right down the seam. It's 1" walnut and I jointed the two so I have a book match pair. It's 18" long way and 12" short way (seam is 18"). I glued it and used 3 20 biscuits. Put it on my workbench using the vise to tension it with 2 clamps. How can I stop the bowing. Now I'm going to have to plane it down and lose about 3/16" of thickness. I may as well just cut it apart and restart

[Jebediah Eckert]

What do you mean by bowed? The glue line bowed apart or it kind of "lifted up" along the glue line towards you?

[Jim Becker]

You mention "book matched" and that generally implies that you re-sawed a board to get that book match. When you split a board like that, there is tension and moisture imbalance that often comes into play. If you did your glue up before the wood had a chance to stabilize, that could account for the issue you describe. Additionally, I'm concerned that you didn't use enough clamps while gluing this panel up...and you need them on both sides of the panel to help keep it flat. Your bench vise really can't be used for this process and you may also need to use cauls to help keep things flat.

If you do need to redo the joint, very carefully rip right down the center of the glue line and then let the boards sit for whatever time it takes for them to stabilize moisture content on both sides. Re-joint the edges and then clamp up again. IMHO, you need a minimum of at least 4-5 clamps and they should be on alternating sides.

[Mike Henderson]

In addition to what Jim said, use some cauls to keep the seams level as you do the glue up.

Mike

[John Lankers]

In addition to what the others have already said, too much clamping pressure can cause bowing. What you want is a tight fitting joint with no gaps, even glue squeeze out at moderate clamping pressure - no biscuits needed. I will try to post a mock up picture later.

[Pat Barry]

I picture the panle didn't actually bow but that the joint line wasn't perpendicular. Re- rip and joint the two pieces. Make sure the clamping forces are equalized top and bottom. Use one clamp on bottom for every clamp on top. Tighten all to equal tension. Cauls or vertical clamps at the seam ends are also helpful.

[Chris Padilla]

Post some pictures, Dave, and we can do a bit more than guess at what happened to your glue-up.

[Mel Fulks]

Agree the resawing is the cause. When I have to to that, I face the saw cuts then plane all remaining wood from the other side. That helps ,but might not completely stop bowing.

[Brian Henderson]

Rip down the seam and re-glue, it isn't the end of the world. I suspect that the wood wasn't exactly at 90 degrees so that when you glued, the error was doubled. Make sure that it's perfectly 90, use cauls to keep the whole thing perfectly flat and re-glue.