[nbo10]

Hi All,
I glued up a smallish panel from soft maple and cherry. The wood sat in the garage for about a month before working with it. The boards went, maple-cherry-maple-cherry-maple, with the outside maple and cherry 3.5" wide and the center maple 2.5" wide. The pieces were 3/4" thick. The end grain was set up as shown in the photos. I glued them up to have the best face up. The panel was flat until I started to thickness it with hand planes. It was cupping while I was planing it. Checking for flatness the center was always lower, and at the time I thought I was taking more from the center. As it turned out the panel was cupping. In hindsight I should have thicknessed the boards to 0.5" before gluing up. But did I do anything wrong during the glue up, setup, planing that could cause the cupping? Could I have prevented the cupping? THanks

The piece was going to be a pizza peel for the wife. I'm not sure how well it's going to work now.

 

[sawdustfactory]

Several possibilities. Wood was not fully dry and by planing from only one side there was moisture differences that caused the cupping. The other is clamping pressure pulled it out of alignment but if it wasn't cupped before planing it's probably not that.

 

[woodnthings]

an easy fix

Easiest would be to rip the boards down their individual centers and reglue. Then you can do a few other things before you reglue. You can turn every other board over OR flip each one end for end. What you are attempting to do is alternate the grain direction on the faces of the boards.

When the end grain has long sweeping arcs, the board will cup on it's own. If the end grain has vertical lines it will probably not cup very much, if at all. Some boards have a mixture of vertical and long arcs and those tend to cup where the grain stops being vertical.
Trying to put the "best face up" is not always the best process as you have discovered. It's always better to rip the boards into narrow strips rather than to have wide boards will long sweeping end grain in my experience...... :yes:

 

[Steve Neul]

You might wipe the concave side of the panel down with water and see if that corrects it. Sometimes if you raise the moisture content to one side it will correct a cup warp. The unknown is if it will stay or not.

 

[Dominick]

Did you joint them by hand or by jointer?

 

[MNsawyergp]

I have to ask you how you are storing this panel. If you lay it flat on a bench or table, the top side is exposed to the air. This side will usually give up moisture which causes it to shrink more than the back side and cup (middle is lower than the edges). If you flip the panel over and store it that way there is a good chance the panel will flatten out. As Steve Nuel suggested, you could run a damp sponge on the concave side and then lay that side against the table.

Watching how you glue up a panel by reversing end grain direction will help greatly, also, but unless you do as "woodnthings" suggested and rip the panel apart and reglue it, you are beyond that now.

Panel storage is key once you glue up several pieces. One thing that helps is to lay the panel flat, but cover it with another panel and add weight. If you go to any lumber store and look at lumber or plywood stacks, the top pieces are usually cupped upward on the edges or ends. They have dried out more and shrunk on the top side.

 

[nbo10]

I jointed them by hand. The boards were folded like a book to have complementary angles. The seems looked tight.

The panel was stored flat on top of another piece. I was trying to hide it from the wife, as it's a gift.

I went ahead and ripped the panel apart on the table saw. I'll flip the cherry end-for-end and glue it up again, after I thickness the individual boards.

 

[MNsawyergp]

Flipping the cherry end for end, yet keeping the same side up does nothing t improve the situation. Alternating grain direction is all about looking at the grain pattern on the end of the board. You have to determine by the growth rings which side of the board is the center of the tree on. This determines the alternating of the boards...center of the tree up, center of the tree down, etc.

 

[woodnthings]

flipping end for end

Flipping the cherry end for end, yet keeping the same side up does nothing t improve the situation. Alternating grain direction is all about looking at the grain pattern on the end of the board. You have to determine by the growth rings which side of the board is the center of the tree on. This determines the alternating of the boards...center of the tree up, center of the tree down, etc.

If you flip a board end for end, you will have the opposite face up. If you rotate it end for end, the same face will remain up. Just so we understand each other... :yes:

 

[nbo10]

I agree with woonthings. Flipping the boards end-for-end puts the opposite face up. flipping edge-to-edge would have the same effect.

I re-flattened the individual boards. Is soft maple harder than cherry? Planing the cherry was super easy. The soft maple was another story. Even after sharpening the blade the maple was a pain.