Fixing cupped boards

[Craig Che]

So I joined some boards to make 9" and 15" wide boards, but somehow they cupped about 1/8th of an inch (nice side is higher, so cutting a 45deg means the middle is slightly longer than the edges). When I glued them up I had them flat, is there a way to get them to flatten out? I tried some braces but it didn't do the trick. Should I try stronger bracing or do I have to get it wet? Thanks for any advice.

[Montgomery Scott]

Did you check to make sure the joined edges were 90 deg before assembly?

[Jason Beam]

How were your panels stored? All stacked on top of each other?

Here's my story, which may help:

I glued up 4 panels for a pair of end tables I was making. These were roughly 28x24" cherry panels when they were done. I was very careful to make sure they stayed flat and when the glue dried, I was pleased. That night I laid 'em all on top of each other ... then couldn't get at 'em for a week or so.

I came back out to the shop a couple weeks later and to my horror, they were severely cupped. Like ... 3/8" or more. I said a whole lot of bad words at first...

But then I noticed a pattern: The top panel was the most severely cupped. The second was less so, and the third even less .. It dawned on me that by stacking them on top of one another, I'd effectively sealed the first panel's bottom face without sealing its top face. The moisture left, things started to shrink and kablam. This exposed the top surface of the 2nd panel a bit, and off it went which exposed ... you get the idea.

I took a couple 2x4's and made some slots about 2" apart that were about 1/4" wider than the thickness of the tops (1" grooves for 3/4" panels). Then set the panels into those slots for a few days. Wouldn't ya know it, they flattened right back out. Much to my wife's releif. She knew how much that cherry cost!

this may not be your problem, but that's the cheapest and least risky fix I can offer. I'd try letting them sit with even airflow for a few days and see if things improve.

If not, you can always rip 'em down, re-joint and re-glue.

[Craig Che]

The joints were with a tongue/groove but they didn't fit really tight on the bottom half, unfortunately I didn't know nearly enough when making them that the joint had to be very tight everywhere.

Jason, it has been a couple of weeks and they were stacked on top of each other. I will try your solution first, would be great if that works.

[Jim Becker]

Yes, if they were stacked together, they likely didn't have equalized moisture change. Sticker them in the shop for awhile for airflow and see if they flatten out.