Cupping Problem - HELP!

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bluthart

New User
Brian
I finished what I had hoped to be the final panel glue up for my newborn son's crib. After removing the clamps the panel looked fine, approximately 27" wide before final rip and nice and flat. It laid on my FLAT workbench for a few days until I had a day off, and now it's cupped very badly. It is already planed close to correct thickness, as I was just planning on a little hand planing to even up any board edges. Any ideas how to get this thing flat again? I really don't feel like doing another panel, but I will if needed. I was really hoping to finish assembly this weekend...:help:
 

Bas

Recovering tool addict
Bas
Corporate Member
You could try flipping the board and leave it on the workbench today. My guess is that the exposed side dried more than the side against the bench.
 

Glennbear

Moderator
Glenn
You could try flipping the board and leave it on the workbench today. My guess is that the exposed side dried more than the side against the bench.

I totally agree with your analysis Bas, as I mentioned in another thread after final machining workpieces need air circulation on all sides. DAMHIKT. :BangHead:
 

Bas

Recovering tool addict
Bas
Corporate Member
After I flip it should I clamp it?
It might help a little, but no amount of clamping will straighten a cupped board. I would simply do exactly what you did with the other side.

I know, it's hard to just flip it over and walk away...doesn't feel very "active"
 

bluthart

New User
Brian
It might help a little, but no amount of clamping will straighten a cupped board. I would simply do exactly what you did with the other side.

I know, it's hard to just flip it over and walk away...doesn't feel very "active"

I guess it would be a good excuse to clean my shop while I'm waiting!
 

Howard Acheson

New User
Howard
In the interest of supplying information for preventing this problem, be sure to never lay a board or glued up panel on another surface without having it stickered (raised off the surface by an inch or two). Air must be able to easily circulate to both sides or unequal moisture content will occur on both sides. It's the unequal moisture content that causes the warping. Don't lean a board or panel against an outside cement or cinderblock wall. Moisture goes right through concrete or cinderblock.

Sometimes stickering the item after it has warped can reverse the process.
 

Canuck

Wayne
Corporate Member
I have also dealt with this same problem a number of times.

I just stickered the panel and laid a cement block or several 1 gallon paint cans on top for weight and it was good to go in about 48 hours.:icon_thum

Wayne
 

bluthart

New User
Brian
Thanks guys! I'm working on it - in the meantime I really DID do a lot of much needed cleaning and organization. Nothing like putting on some good music and getting lost in your shop for a few hours! I'll keep you posted on the progress.
 

bluthart

New User
Brian
And by the way - these are the first panels I have ever glued up - so they were actually coming along quite well until the cupping on the one panel happened. The other one was set upright leaning up against a shelf and must have equaled out - it's flat as can be.
 

nelsone

New User
Ed
Try leaving the panel on a concrete floor overnight, cupped side down. It will pull moisture from the concrete and reverse the cupping. I've done this a couple times and it works pretty well. It won't be perfectly flat, but may get you close enough to sticker and use some weight to coax it along.
 

kooshball

David
Corporate Member
Depending on how bad the cup is you might want to clamp it so that you get good surface contact to repeat the exact situation that likely caused the issue.
 

Ken Massingale

New User
Ken
I'll say what I suspect Mike was nice enough not to say....

27" wide and cupped badly, I'd start milling stock for another panel. I hope I'm wrong.
 

junquecol

Bruce
Senior User
Now you have insight as to why we spend BIG BUCKS to buy Bessies. Clamp it up, and then stand the whole assembly upright on the floor.
 

bluthart

New User
Brian
Now you have insight as to why we spend BIG BUCKS to buy Bessies. Clamp it up, and then stand the whole assembly upright on the floor.

I did that to begin with, but then after I unclamped it a few days later, I laid it on my bench to hand plane at a later date... and so here we are.
 
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