Help! My tabletop cupped!

[Jeremy Kargas]

Okay, I've got a problem. I'm building a buffet and when I went to put the solid wood tabletop on, I found that it had cupped a little less than 1/8". When I glued it up, it was perfectly flat. I alternated the grain patterns and kept the widths of the boards from 3"-5" or so. The piece is 66" x 19", so it will not fit through my planer. I need to know what I can do to fix this situation. I just got back from the local cabinet shop and tried running it through their drum sander, but all that did was push the board flat as it was going through and when it came out the other side, it popped right back to where it was. The top will be attached with the 3/8" offset tabletop fasteners. I was thinking of possibly cutting some relief grooves in the bottom so that when I attach it, it will pull the piece flat, but I figured I would come to you guys first to see what you have done. I'm new to this hobby so any help would be much appreciated.

Thanks in advance.

[tod evans]

attach a cross grain batten using slots in the batton to permit movement.....02 tod

[John Lucas]

I am not one to use force against nature's force. You lose too often. I would mount it as you werre planning to allowing it to move with seasonal changes. The 1/8" cupping doesnt sound that bad. I would use belt sander or hand planes to level it out and then resand to finish.

[John Miliunas]

Jeremy, Todd Burch, woodworker extroadanaire, did a short tutorial on exactly what you're encountering. Check this out: http://www.sawmillcreek.org/showthread.php?t=5559

Hope that's of some help...:) :cool:

BTW, welcome to the Creek!!! Hope to "see" you around real often! :D

[Jim Becker]

A 1/8" cup doesn't sound all that insurmountable. Dampen the "inside" of the cup with a little distilled water to help it along, set it on some stickers for a little while for it to relax and then fasten it to your carcass with whatever method you planned on using to deal with wood movement. It should flatten out acceptably without grinding off more material through sanding. Once it's down, remember to knock down the raised grain with a little 320 if you already did your final sanding of the panel.

Oh...and welcome to the 'Creek!

[Ben Abate]

I believe I might go with Tod's idea sort of. This would probably work, clamp the top to a stable bench to make it flat. By the way this is going to be a bit of work. Lay out a large dovetail across the grain, incorporate this into your manner of attaching your legs. This could serve two items for you. one is that it will straighten out your top and two it will let the wood move. If you want you could use a small amount of glue in the center area. Other wise you will not need any adhesive. I hope I am not confusing about my discription.

Ben

[Howard Acheson]

So much for the myth that narrow boards and alternate grain direction will keep a board flat.

That said, how did you store the panel after you initially flattened or sanded it? Sounds like it was in a position that did not allow free circulation of air to both sides. If that's so, then Jim suggestion to dampen the one side and re-sticker could work.

Also, 1/8" ain't much. In the shop I was involved with, a panel like that was considered "flat" if it was intended for being attached to some sort of a frame. If you can flatten it with hand pressure, just properly attaching it to its frame will flatten it out.

[tod evans]

wood will move untill it turns to dust, we as builders must take this movement into consideration with our designs and methods of execution. there is no amount of prep work or finishing i`m aware of that will keep wood from moving. only by building with woods natural movement in mind will our projects stand the test of time......02 tod

[Jeremy Kargas]

Thanks everyone for your replies. If you have anymore, feel free to keep them coming. I'm going to try Jim's method first (seems the easiest). If that doesn't work, I'll be back. (Actually I'll be back either way since I'm on this site dang near every day since I found it) Jim, I've got one question for you... Which side do I lay it on once I dampen it? The cupped or the bowed?

Thanks again everyone.

[Steve Cox]

First question would be "how did you store the panel?". If it was flat on a bench top that probably caused your problem. After gluing up a panel I always store it on edge so that air can get to all sides. This policy came about after some issues very similar to yours.:cool: :D As for how to fix it, I like Jim's idea but another method was suggested to me but is untried. Take the panel and place it on the floor of your shop (it its' concrete) with the concave side down. That will pretty much give you the same conditions as dampening it. The 1/8" doesn't sound too bad. You can probably bring it flat by attaching it but I'd try to straighten it a little first.

[ROBERT ELLIS]

Jeremy,

For what it's worth, heres my .02 cents. Around here, all the "cherry repoduction furniture shops" always screw their tops directly to the carcase from the underside. They have been doing this for decades on expensive furniture. While I was always taught to use table top fasteners, or their equivalent, they attach them "somewhat" contrary to the way all the books and professionals mount them. They have a little secret I'll share with you. (I learned this from my ww friend thats been building cherry furniture for over 30 years) The trick is to pilot the hole through the apron, (on tables) or casework, from the inside at an angle drilling the hole a little larger than the screw itself, then they drill a shallow, but large enough hole to accomdate the screw head. That's the secret. The extra gap in the screw width allows for wood movement. Being reluctant to change and comfortable with using table fasteners, I finally caved in after trying thier technique. It works. I still use my table top fasteners most of the time, but when I get a cupped top, I simply clamp it to the piece and use their system. I'll add that this way of attaching them I have yet had any problems, or any call backs on my furniture.

The only word of caution I would add would be to make sure your lumber is in an acceptable moisture range if you should you opt to try this...

Just another idea for you...

Robert

[Rob Will]

wood will move untill it turns to dust, we as builders must take this movement into consideration with our designs and methods of execution. there is no amount of prep work or finishing i`m aware of that will keep wood from moving. only by building with woods natural movement in mind will our projects stand the test of time......02 tod

sorry for the hijack here....
Tod,
I'm interested in some natural edge table tops etc. This will be in a cabin with somewhat of a rustic feel. If you were designing say perhaps a coffee table, how thick would the final slab be and how would you handle the drying process to eliminate "some" of the future problems? Should "slab style" furniture like this incorporate a frame below the top and how best to attach the two?

Thanks,
Rob

[Marcus Ward]

The cup is a FEATURE designed to contain SPILLS. Yeah, that's the ticket.

[Mark Rios]

I think I read somewhere that if your table top is cupped then you need to fix it with a BIG saucer.:D

[tod evans]

sorry for the hijack here....
Tod,
I'm interested in some natural edge table tops etc. This will be in a cabin with somewhat of a rustic feel. If you were designing say perhaps a coffee table, how thick would the final slab be and how would you handle the drying process to eliminate "some" of the future problems? Should "slab style" furniture like this incorporate a frame below the top and how best to attach the two?

Thanks,
Rob

rob, you`re asking a pretty broad question! when you say " natural edge" and ask how thick.....it makes me think you haven`t cut the lumber yet? i have never operated a kiln and can only say that drying wood in a kiln is an art, especially when you`re talking fat lumber. the rule of thumb for air drying stickered, covered lumber is 1 year per inch of thickness. as for applying an apron to your table to help eliminate warpage i shoot for at least 2 1/2 times the top thickness in apron depth.....hope this gives you some ideas? ..02 tod

[Jeremy Kargas]

Well, turns out I didn't have to do anything. Running it through the drum sander must have thinned it up enough to where I could pull it down with the fasteners. I did have to give it a little extra and used Robert's method to pull down one of the corners because the table top fasteners weren't close enough to the corner, but it worked! I've just got 2 more doors, 2 more drawers and the crown molding left. I will post pics when I'm done!

Thanks for all your help!

[John Miliunas]

Well, turns out I didn't have to do anything. Running it through the drum sander must have thinned it up enough to where I could pull it down with the fasteners. I did have to give it a little extra and used Robert's method to pull down one of the corners because the table top fasteners weren't close enough to the corner, but it worked! I've just got 2 more doors, 2 more drawers and the crown molding left. I will post pics when I'm done!

Thanks for all your help!

Well, good for you, Jeremy! And now you know of several other methods if/when it happens again, as the next time, you may not get quite that lucky! (I know if it's me, I never get that lucky!!!:rolleyes: ) Waiting on the finished project pics! :) :cool: