Walnut table is bowing!

[petertay15]

Last fall we built a small dining table out of 3/4 walnut. 37 x 60 inches. The wood was airdried for two years and perfectly flat. To make the top look thicker, we face-glued another 3-inch board under the top all around. Then there are 4-inch aprons all around, also 3/4 walnut. I did not think to put any other support under the top, assuming walnut is plenty strong. (The flat boards glued under the ends were made of short grain boards, so they would shrink/expand with the top.

Now 4 months later, I get a call telling me the table has bowed down 1/2 inch in the short dimension. Top and aprons are bowed down together. Yikes! What to do?
For the moment, I told him to turn the table over and leave it that way.

I assume I will have to replace the aprons on the ends and add a few more supports across the width. Do you think the table top will flatten out?
--Peter

[Phil Thien]

Ask them if they fixed the leak that soaked the top with water?

Just kidding. 

Or am I?

[petertay15]

Because someone will ask: the top was made of just a few wide boards, and they were flat sawn. --Peter

[jteneyck]

Last fall we built a small dining table out of 3/4 walnut. 37 x 60 inches. The wood was airdried for two years and perfectly flat. To make the top look thicker, we face-glued another 3-inch board under the top all around. Then there are 4-inch aprons all around, also 3/4 walnut.  I did not think to put any other support under the top, assuming walnut is plenty strong. (The flat boards glued under the ends were made of short grain boards, so they would shrink/expand with the top.

Now 4 months later, I get a call telling me the table has bowed down 1/2 inch in the short dimension. Top and aprons are bowed down together. Yikes! What to do?
For the moment, I told him to turn the table over and leave it that way.

I assume I will have to replace the aprons on the ends and add a few more supports across the width. Do you think the table top will flatten out?
--Pete

Any idea what the MC was when you built it?  Was the bottom finished?  How was the top attached to the aprons? When you say "last Fall" do you mean a couple of months ago?  

John

[petertay15]

John, Yes, we made it a couple months ago. The top is finished on both sides with Arm-r-Seal. It is attached to the aprons with the clips that Rockler sells. I didn't measure the moisture of the wood, as we have built lots of other furniture with this same wood with no problem. The humidity swing here is quite wide. It might have been 90% in our outdoor shop when we made the table, and it might be 25% in the owner's unhumidified house.

[Kansas City Fireslayer]

A 1/2”’is a lot to say the least. It’s almost hard to believe. Have you seen the table yourself after the movement? Pictures would help. Wide boards or not, somthing is terribly wrong with the construction or design if it has moved a 1/2”.

[Stwood_]

Was there a big crotch section in the end of one of the outer boards? Or one of the apron boards?

[petertay15]

No, I've not seen it yet. I'll get over there in a day or two to pick it up and bring it to my shop.
The sub-zero temps have lifted, so we'll fire up the wood stove and get the shop temp up to 60 or so.
I'll report on it then. --Peter

[Earl Kelly]

Last fall we built a small dining table out of 3/4 walnut. 37 x 60 inches. The wood was airdried for two years and perfectly flat. To make the top look thicker, we face-glued another 3-inch board under the top all around. Then there are 4-inch aprons all around, also 3/4 walnut.  I did not think to put any other support under the top, assuming walnut is plenty strong. (The flat boards glued under the ends were made of short grain boards, so they would shrink/expand with the top.

Now 4 months later, I get a call telling me the table has bowed down 1/2 inch in the short dimension. Top and aprons are bowed down together. Yikes! What to do?
For the moment, I told him to turn the table over and leave it that way.

I assume I will have to replace the aprons on the ends and add a few more supports across the width. Do you think the table top will flatten out?
--Peter

Check for heating vents in the area of the table. Heated dry air blowing directly on a table can do this.

Earl

[rwe2156]

How as the top fastened to allow for movement?