Cupped Top

[ToddW]

I have a 1/2" quilted maple top for the project I'm working on, and I wanted to laminate it to a piece of 3/16"purple heart before attaching it to a chambered back. The top is cupped, but I had no trouble flattening it out when I simply pressed it to a flat surface.

But then I glued it to the purple heart, which curved to the cupped top, after which I couldn't flatten it anymore Several trips through the planer removed the purple heart, after which I glued the top to a new piece of purple heart, but this time I clamped both to the work bench surface which is holding it flat as it dries.

I figure after the first attempt, to flatten it I had to either stretch the glued surface of the purple heart, or compress the unglued side. This time, I'm hoping that to return to cupped, the maple will have to stretch the purple heart.

Has anyone tried this, and do you think the glue will hold up? Pressing it flat before laminating was pretty easy, but even that slight pull of the maple away from the edges, if it is constant for years, seems like a bad thing. . . .

Thanks,

Todd

[Jon]

When gluing cupped pieces (only softer woods) I use supports at the top and bottom of the piece to make sure it doesn't help whatever the cupped piece is gluing to warp or change shape over time, pine works. The same goes for gluing multi-lam necks, I use Iron bars on both sides to assure nothing will change shape.

[ToddW]

When gluing cupped pieces (only softer woods) I use supports at the top and bottom of the piece to make sure it doesn't help whatever the cupped piece is gluing to warp or change shape over time, pine works. The same goes for gluing multi-lam necks, I use Iron bars on both sides to assure nothing will change shape.

Wish I'd thought of that before I glued up the first time. I used multiple gluing cauls instead.

I do have a support on top also, but I think it's the bench that's keeping the two pieces flat right now.

Todd