What to do with bowed boards after resawing

[Geoff Harris]

I've resawn a 4/4 hard maple board with the intention of using it for the back of a bookshelf (ship lapped). The piece is 7 feet long. I need close to that length. Of course the pieces have bowed in length and now I've got a couple of bananas.

So do I sticker and clamp them hoping that eventually they will flatten out or do I just go ahead and use them since the pieces will be screwed to the back and are thin enough that the screws will straighten them out. They will be attached at the top/bottom and middle fixed shelf.

This is the first time I've tried resawing such a long piece and I'm not sure that they will ever flatten out. I certainly don't have the thickness to joint them flat.

Geoff.

[Steve Schoene]

Whether they will straighten out with stickering and weighting depends on why they warped in the beginning. If it was due to different moisture contents between the inside and the out, that should equalize and the boards straighten. Try stickering, and see what happens.

But if it was a drying defect, such as case hardening, or other stresses in the tree, then it won't naturally straighten out. Whether I would use it, mechanically forcing it into place depends quite a bit on the structure of the bookcases. If otherwise sturdy and the force required to straighten the back boards small enough that they would not likely to be pulled out of shape over the long term by the pulls of the back, then I'd probably use the boards.

[Chuck Tringo]

Unless they are bowed so bad that they look like a half pipe, I would go ahead and use them. The screws and ship lap should help keep them in place, I would just ensure that any bowed stock is placed with at least one, preferably 2 straight boards on each side.

[Dell Littlefield]

I am sure you have also considered movement after installation. This would limit the number of fasteners to hold them in place.

[Geoff Harris]

Thanks for the responses. I've stickered them and clamped them flat. I'll leave them that way for the rest of August and see what happens.

They will ultimately be milled to 3/8 inch so I think they will flex pretty easily.

When I do attach them they will have one screw at the top, one in the middle and one at the bottom, that should allow for wood movement.

I guess the only way to get really flat boards is to mill or cut the outside pieces away and only use the middle. Kind of disappointing. I've successfully resawn shorter boards without warping but perhaps I was just lucky. These boards checked out at less than 6% moisture content when they were cut.

[Geoff Harris]

I just wanted to follow up on this thread with the results one month later.

I went away for 3 weeks and left the bowed boards clamped flat and stickered. They are all now flat

Geoff.

[Jim Becker]

Sounds like it was just a variable moisture situation with the original board that time has adjusted for you. That's great news!