ways to flatten a 11" wide cuped board

[Kurt Forbes]

How would you flatten a wide cupped board? plane both sides?
Rip cut them then work with the much less cupped boards? Would it even be safe to rip cut on a bandsaw?

[glenn bradley]

You can measure the difference between the cupped ends and your desired flat surface to fetermine how much material you will have to remove to get flat. My bet is it will not leave you much thickness. A cure for this is to rip the board, joint and plane the halves and glue them back into a flat panel.

[John Headley]

I agree with Glenn. I've flattened wide boards with hand planes many times. If a wide board is cupped, in most instances if the cup is noticeable with the naked eye, it will require removal of a significant amount of stock to get it flat. Plus, once it is flat, there is no guarantee that it wont continue to cup more in the future. Ripping the pieces and gluing will minimize the loss of thickness, and reduce the risk of cupping later.

[scott spencer]

Yep...I'd rip it, joint and plane the two pieces, then reglue it. It'll probably end up more like 10-3/4" wide.

[Greg Deakins]

it depends on the project. If it were a table top, where support would keep it flat after assembly, and I had the time, I would try to flatten it back with laying it cupped side down on a flat surface, with a board ran lengthwise along crown side and a few heavy items. If it were not so important to have an uncompromised board, then I would choose the route of the others in the glue up.

[Jules Dominguez]

It depends on how bad the cup is. If it's bad enough that you can't spare enough thickness to flatten both sides, the only alternative is to split it, flatten and re-glue as recommended above.
My cherry stockpile is rough lumber 1 1/8 thick. I can usually afford to flatten the whole width of a cupped board and end up somewhere between 3/4" and 7/8" finished.
I've found the easiest way to flatten one side is to put the concave side up, wedge it and clamp it, and handplane diagonally across the board, just enough to take off the high sides to the point that the board will ride through the planer stably with the concave side down. (Sometimes it also requires a few lengthways passes on the areas of the sides which have been taken down by the cross-planing.) Then flatten the convex side with the planer, turn it over and finish the concave side. I have a lot harder time dealing with twist than with cup.