Fixing a cupped board on tabletop

[Scotty Gadlin]

Hello everyone,

I built a farmhouse style table about 6 months ago from this build.
http://ana-white.com/2012/06/plans/f...armhouse-table (http://ana-white.com/2012/06/plans/fancy-x-farmhouse-table)

I wanted it to be rough and simple, however
One of the 2x10 boards have developed significant cupping (as shown in pictures attached). I was trying to research how to fix this and I am somewhat confused on the best way to go about it. It seems I could try a few different things that may or may not work permanently.

The boards (2x10) that comprise the table top are horizontally joined with pocket screws.

I have concluded that my options are
1)Wet the concave surface (in this case the top finished side) and try to clamp it flat and allow it to dry

2)Heat the convex surface (in this case the bottom unfinished side) and clamp


3)Do a combination of #1 and #2

4)Make kerf cuts on the bottom of the board, fill with a spline or other wood filler and clamp flat


or
http://www.sawmillcreek.org/showthre...a-cupped-board (http://www.sawmillcreek.org/showthread.php?5559-Flattening-a-cupped-board)
as an aside question if I did this technique would it be ok to make the kerf cuts on the concave side, I cant put kerf cuts on the convex side because it is the finished top side.

I would appreciate any advice, I really do not want to replace the board because we used a vinegar steel wool stain that would be hard to replicate the exact color
319983319985319984

[Jay Jolliffe]

Is this new or has it been like that for a long time. I have a Mahogany counter & in the summer it curls a little bit because of the moisture in the air..When fall & winter shows up the curl goes away. Its wood, its going to move .

[Scotty Gadlin]

Built it about 6 months ago, so a new occurence. It may have been a little cupped to begin with, but has progressed significantly over last few months

[Prashun Patel]

That's quite a cup!

I would first wait a full year and see the range of what you're dealing with.

Was it surfaced and built in a climate similar to the room it's in?

I would dis-assemble the top and resurface and re-joint everything so it's square again. I would also take care to alter the growth rings. If this wood is just prone to such seasonal movement, at least you can have a globally flat (albeit slightly wavy) table instead of a potato chip.

There's a chance the wood was just not properly dried, or that the climate changed caused a one-time warp.

[Scotty Gadlin]

It was built in similar environment, I have little doubt it was not properly dried (got it from Home Depot). I did alter the growth ring patterns on the 4 boards, this is the only one with problems.

[Bill Orbine]

Lack of balance may have contributed to cupping. You have finished the top side but not the bottom?

If you can remove the cupped board from the table..... take it outside lay the cup face down in the damp grass and the sun will heat the convex. Doing a double whammy. It will straighten the board but keep an eye because it will over do the un-cupping.

I suggest you balance the finish both sides. However, while you may have achieved the desired result initially, the lumber can still revert back to cupping. Keep your finger crossed.

[Pat Barry]

I do not think that your methods 1 thru 3 will work (for very long). What you see is what nature intended for this. Your method 4 might have the best chance although I think - you are not going to like this - that you need to remove the board, rip it down the center, joint the edges, reglue it back together and reattach it to the top. I really don't see any point in waiting a year. So what if it gets a little better in a drier season, next summer it will go back to what you now have.

[Scotty Gadlin]

Yes, I definitely learned my lesson on the importance of finishing both sides. I am new to building/wood working. I have heard of doing the board with convex side up on the grass before, but didnt want to risk having the rest of the board (the other 5 -7 feet) have reverse cupping. The cup is mainly just at this one end of the 8 ft long board.

[Andrew Hughes]

I think a board with a slightly differant color would be better than a wonky board that looks like like it's trying to spill your food.🍫

[Scotty Gadlin]

I think a board with a slightly differant color would be better than a wonky board that looks like like it's trying to spill your food.🍫

Ha, excellent point. Still will try to fix it first though. Will be good experience for when it happens again.

[John TenEyck]

You can do the wet grass, hot sun thing, but it will just go back to the way it now is when it dries out and cools down again. Clearly the wood was not at EMC with your shop when you built the table. Not finishing the bottom might have made the result a little worse, but it would have happened to some degree anyway. I agree with Andrew; better to have a slightly different color than a wonky board. Cut it off and either flatten it properly, or replace it with a new board - after it has come to equilibrium with your shop or, better still, where the table is sitting. If you were using construction lumber, that means letting it sit for probably at least a month before working it.

John

[Brian Holcombe]

I've had the same experience as John in attempt to fix a cupped panel with those type of methods. The only fix I've found that works is to flatten the board again, and I suppose the rest of the table as well since they're all the same thickness currently.

Is the board only attached to the stretcher on one side along the width? I would think that would add to the problem, support at two points along the width will help to minimize such problems, IMO.

[Scotty Gadlin]

I've had the same experience as John in attempt to fix a cupped panel with those type of methods. The only fix I've found that works is to flatten the board again, and I suppose the rest of the table as well since they're all the same thickness currently.

Is the board only attached to the stretcher on one side along the width? I would think that would add to the problem, support at two points along the width will help to minimize such problems, IMO.


Ii is only supported about half way, this could definitely be contributing
Thanks

[Dan Hahr]

If this is a rough table anyway, you could place several battens across the bottom of it with lag bolts pulling the boards flat. I'd probably use something about two by three inches, the stiffer the better. Short of that, you'll have to disassemble the table and either rip, joint, and plane the top boards flat and glue them into one large panel or redesign another top. Construction lumber is going to move unpredictably unless you dry it out properly which would take months.

Dan

[Kent A Bathurst]

Using the pluperfect tense of the verb phrase "to be screwed": Scotty's table had been scrod by the time he posted here.

Sorry, brudda, but there is no "easy out" here.

Take yer lumps, replace the offending board. Take that opportunity to rework the battens, and apply the other excellent technical points raised here. Mebbe the finish will look OK. If not, I'd think that the same species and the same finish schedule will even out over time.

Just one of the lessons learned.......we have all been there.

[Scotty Gadlin]

If this is a rough table anyway, you could place several battens across the bottom of it with lag bolts pulling the boards flat. I'd probably use something about two by three inches, the stiffer the better. Short of that, you'll have to disassemble the table and either rip, joint, and plane the top boards flat and glue them into one large panel or redesign another top. Construction lumber is going to move unpredictably unless you dry it out properly which would take months.

Dan


Thanks, I will give this a try

[Robert Engel]

I think where you went wrong was using too wide boards + not supporting all the way to the edge.

I'm with Kent here, once a thick board cups like that, there's not much hope short of ripping it down, squaring the edges and regluing back together.

And it may still warp even after that.

Using construction lumber for furniture projects is a perilous undertaking because the moisture is so high unless you take care to let the stock acclimatize.
You need to sticker it and let is dry out at least a month or two or check the moisture content with a meter.

BTW, I've had plenty of boards cup even though they were finished both sides.
Don't know how to explain it, but it happens.

[Greg Cuetara]

Not that this is an ideal solution but why wouldn't his idea #4 work. I have seen others make kerf cuts on the bottom side of tempermental wood to 'flaten' it out. The cuts could go about half way through and then filled with epoxy.

Why wouldn't this work? So many people just say to rip down, joint, plane and then glue back together and that is the only way. This is not a Thomas Moser piece costing tens of thousands of dollars. I would think maybe a combination of a few kerf cuts on the underside filled with epoxy and then some straps on the underside to help it stay flat over time. It might even be worth it to try and get 3/16" or 1/4" steel plate about 2" wide, then paint it to match and screw in from underneath. The only reason I suggest steel is to minimize what is sticking down from under the table.

Greg

[Scotty Gadlin]

So I decided to make a bunch of kerf cuts with a circular saw, to the distal half of the board. It was moderately successful, about 60% improvement. Makes a huge difference though.

[Charles Lent]

Another method for dealing with "construction lumber" when you want to make furniture with it is to make it into quarter sawn. Rip the pieces into 1 1/2" squares or squares of whatever the thickness of the wood is, then rotate the squares until the grain is vertical and glue it back together. With the grain lines running across the thickness of the board (in this case vertical) it will be much less likely to cup, although it will still shrink. I've never done this with long boards, but it should work. My experience has been making pine end tables and coffee tables.

Charley