Need advice

[Harley Friedman]

I'm a newbie, so please forgive me if this is a dumb question.

As a holiday project, I'm trying to do a version of this scrabble board (http://www.sawmillcreek.org/showthread.php?t=15022). I'm not crazy enough to try to do anything this fancy -- I'm making a math game for my kids, wanted to try to make a board with ridges to keep the pieces in place. My frame is MUCH simpler than this one.

So, I started with 3/8 baltic ply, ran it over the TS with a blade with an 1/8" kerf to create the first set of grooves. Cut 1/8" oak strips and glued them in. Turned the board 90 degrees and did the same, and then glued a second set of strips in. I built the whole thing bigger than I needed, and then trimmed the edges down to size. So far, so good. I was feeling pretty proud of myself.

Then I got to adding the frame on, and discovered that the board wasn't flat any more. It's now bowed with the edges/corners higher than the middle. It definitely was flat when I started. I assume that the act of gluing those strips in has pulled the board out of shape.

Which leads to two questions:

1. What could I have done to avoid this in the first place?
2. What can I do to save it, if anything?

I do have some guesses, but looking for knowledge.

As for #1, I have several ideas. I expect the main problem was starting with stock that was too thin. I wonder if I had started with 1/2 ply if I would be in better shape.

Also, the oak strips had some bend to them -- the board I started with seemed quite flat, but once I cut a strip that was 1/8 x 1/2 each strip was no longer quite straight. I glued them in with the highest point in the middle, and clamped them down, because that was the easiest thing to do. Interestingly, if this was the problem I would expect the board to be warped the other way (center highest). Perhaps I should have alternated the warps so they would "cancel each other out?"

Last, I used regular wood glue rather than CA. Is that causing the problem?

As for #2, how to save this project, I have a few ideas also:

A. Don't. I have plenty more material. Suck it up and start over.
B. Glue each edge of the frame on one at a time, clamping the board and the frame to a flat surface. (I can't figure out how I would clamp the whole thing at once, but I can clamp each side one at a time)
C. Option B, but reinforce each side with a spline running the length of the joint.
D. Option B, but reinforce each side with some dowels.

Thanks for help in advance!

[Philip Rodriquez]

There are a number of forces at work, all of them are okay.

First, depending on the depth of your grooves, you may have impacted the strength of the plywood. Not a big deal because this is a game board and not a dining room table.

Second, non-pva glue is fine for your application. The additional strength of PVA is not necessary for joints that will not be subjected to any stress.

Third, and I'm just guessing, it was likely the moisture from the glue that caused your board to warp... but it could have been your clamping... Both are not uncommon and not a big deal. Your next step is simply addressing it.

To address your issue, make a frame that captures the panel and forces it flat. Since the board is plywood, you do not have to worry about any wood movement. The entire board can be glued in place.