A slight issue

[Jak3]

Hello all!

I've recently been working on the top for my side table build. As I started with the sliding dovetails on the underside I noticed a slight issue.

This glued panel is 18" by 18" and I've flattened it relatively flat twice with a no 7 jointer. It has cupped significantly. At it's greatest point, the gap is a little over 3/16". I expected a large glued panel to move but I've seen panels over twice this size not move as much. Not sure what happened.

I'm not sure what to do now. Should I keep planing it? I fear taking too much off now. Should I scrap the sliding dovetails and rework it so that it can be attached with screws?

Any help or insight is appreciated, thank you!

 

[Mike Davis]

Finish the dovetails and make the braces that slide in a little beefier to help hold the panel flat.

May have to clamp the panel to some very heavy beams like 4x4 to get the dovetail braces to slide in.

 

[Graywolf]

+1 on this, I'd brace it while completing the dovetail as well

 

[mbromley]

I'm battling the exact same issue with a top for my dresser. Planed it flat after cupping out of the glue up and now it's right back to where it was. I've thought about cutting some relief cuts in the bottom side and then screwing it down to my dresser case to try and flatten it. Could you use relief cuts?

 

[Jeff]

I'm battling the exact same issue with a top for my dresser. Planed it flat after cupping out of the glue up and now it's right back to where it was. I've thought about cutting some relief cuts in the bottom side and then screwing it down to my dresser case to try and flatten it. Could you use relief cuts?

A few cross-grain battens screwed to the top will be better than relief cuts. It's kind of like a table top on a smaller scale.

 

[Mike Davis]

This is usually an issue with flat sawn boards and moisture being more available on one side than the other.

Can you sticker the top so air can circulate freely and let it acclimate for a couple weeks?

 

[Charlie Buchanan]

I’m 100% with Mikes last reply. There’ Stress in there somewhere. Probably from more moisture on one side. Sticker itboth sides so air can circulate and put some weight on it for couple of weeks. That way you’ll know if it is a permanent problem.

 

[SubGuy]

This is the right call. Agree with both Charlie and Mike!

I’m 100% with Mikes last reply. There’ Stress in there somewhere. Probably from more moisture on one side. Sticker itboth sides so air can circulate and put some weight on it for couple of weeks. That way you’ll know if it is a permanent problem.

 

[JimD]

I agree with the other comments. I will also add that the aprons of a table, because their orientation is different, are very stiff in the direction of the bow. So if you fasten a table top to the aprons, it will effectively eliminate the bowing.

 

[Roy G]

Jacob, I had a similar problem with a table top. Planed it and left it overnight on the workbench. Next day, it had cupped quite a bit. I turned it over so the other face was up and left it overnight. It had flattened out so I could finish the table. You could try this before you do all the above suggestions.

Roy G

 

[danmart77]

Well Jacob you have some good advice here and some real good advice to think on.

Since you are hoping to equalize the moisture on this glued up panel - which makes sense I would avoid flipping and hoping for the same amount of movement. Just put stickers under it and some weight and good air circulation on top and bottom like the others said.

Here's my 2 cents before you are back here again with a cup:

When you get it flat or close to flat, remember this board and how it behaves. Put your sealer coat on both sides at the same time and let it dry slowly and NOT in the sun.


The piece of pine in the photo was part of a lesson. Most of the students did not know the cup goes away from the pith most every time. I sprayed some water on the board and left it overnight accelerate the movement. The board cupped to the outside of the tree so the 16" pine was cupped 7/8" in the center and stayed there for a couple weeks or more. Time to experiment and learn.

I veneered it with thick veneer that "everyone says" you have to veneer both sides or it will cup. Is that so? Must be another Youtube revelation.

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Well seeing is believing. Its a good practice to veneer both sides in some cases. Like gluing this veneer to 1/2 particle board.

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Good Luck

 

[Jak3]

Thank you all for your valuable input. I appreciate y'all sharing your experience with me!

I'll try out one of the remedies and see what happens. I'll post a follow up in the next few days.