I was wondering if anyone has a trick to taking the cup out of a board. I had a couple boards I had finished to 3/8" thick and 6 3/4" wide. I left them sitting for a couple months since I had no time to finish my project. I take a look at them again now, and I see that they have a slight cup to them now. Nothing too serious, but it would be noticeable on what I'm making.
Sometimes you can dampen the concave side and let it sit awhile. Most folks rip the board into smaller strips, flipflop each one so that the cup is alternately on each side,Glue them together, and then plane it flat.
A bit of weight on it after you wet it like Tom said? Or put them face to face and clamp down over the length with cauls?
I have seen pros like Norm Abram make small relief cuts on the back of the cup and it will allow the board to flatten. Works good if the cuts will not be seen.
Don
With 3/8 it would not take much to flatten . Clamping is a good way to do it without destroying the boards. May not have to wet the wood . Clamp to a flat surface or back to back use a lot of clamps.
Drying the convex side works for me. Expose it to a heat source or the sun in summer and monitor it. A thin board will move in a day or two. Joe
Quote from: locustoak on October 25, 2009, 08:02:22 PM
I was wondering if anyone has a trick to taking the cup out of a board. I had a couple boards I had finished to 3/8" thick and 6 3/4" wide. I left them sitting for a couple months since I had no time to finish my project. I take a look at them again now, and I see that they have a slight cup to them now. Nothing too serious, but it would be noticeable on what I'm making.
expose the convex side to the sun...
monitor closely.. you mave to dampen the convex side a bit.....
Quote from: IMERC on November 01, 2009, 11:58:03 PM
Quote from: locustoak on October 25, 2009, 08:02:22 PM
I was wondering if anyone has a trick to taking the cup out of a board. I had a couple boards I had finished to 3/8" thick and 6 3/4" wide. I left them sitting for a couple months since I had no time to finish my project. I take a look at them again now, and I see that they have a slight cup to them now. Nothing too serious, but it would be noticeable on what I'm making.
expose the convex side to the sun...
monitor closely.. you mave to dampen the convex side a bit.....
Do you mean dampen the concave side? Joe
yur gonna make me try this tomorrow ain'tja...
now I'm not so sure...
Do you mean dampen the concave side? Joe
yur right....
sorry about that...
what could I have been thinking of...
so busted as I slink away....
Don''t beat yourself up. you were trying... ;)
With a board as thin as 3/8 a few simple braces on the back side of the wood will flatten it out and keep it flat even after it is integrated into the piece. This of course would only work if you were using the board in an application where the bracing would not be seen. I would be concerned that it would warp again without being braced even if you get it flattened prior to installing it.
Thanks for the help everyone! What I ended up doing was putting the peice beside the wood stove, and I let the heat bend the board for me. I let it sit beside the stove too long the first 2 times and it started cupping the other way. I eventually got it right. It was only 14" x 7" x 3/8", so it was easy to do.
Sure hope it works long-term: I'd be worried about it re-cupping with humidity or moisture contact. Keep us posted on whether it stays "uncupped" for you.
Lj
I'm bettin' it will stay flat if both sides have equal exposure to the atmosphere. It probably cupped because one side was exposed and the other was not.