Replies

1. 
   HowardAcheson | Feb 16, 2007 01:41am | #1

   Leave the top opened for a few days whenever moving an item from one environment to another. That way any change in humidity can equally affect both surfaces and there should be no warping. It's also a good idea to drill some holes for air to get into the cabinet so that future changes in relative humidity can be dealt with.

   At this point, try leaving the lid open for a few days. It should get pretty flat. If need be attach some cleats across the grain from the bottom. Be sure to put some slots in the cleat for the screws so the top can freely expand and contract.

   Breadboard ends would not have helped. You would have had slightly less curvature on the ends but the center would have warped the same amount as it has already.

   Howie.........

   
   

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   Edited 2/15/2007 5:44 pm ET by HowardAcheson

1. 
   JohnWW | Feb 16, 2007 02:44am | #2

   Howie,

   I am going to have to respectfully disagree with your assertion that the problem is caused by unequal gain or loss of moisture from the top and that it will be corrected by letting the moisture equalize. 

   A flat sawn board that is milled flat at a certain moisture content will cup when it gains or loses moisture and this is caused by the cellular structure of the wood.  Uneven moisture gain or loss can also cause problems this way, but a large unrestrained top moving into a much drier environment is much more likely to be suffering from simple wood movement as the panel lost moisture.

   I do agree with you that breadboard ends would not be all that effective in keeping the top flat.

   John White, Shop Manager, Fine Woodworking Magazine

   Edited 2/15/2007 6:54 pm ET by JohnWW

1. 
   fsg | Feb 16, 2007 03:04am | #3

   With all this said and being new to furnitue building, should I just scrap the top and start again?  I have another top I can use. It is constructed with 3 1/2 inch quartersawn boards ,biscuited together with the rings alternating. This time I would put supports on the underside of the top. However, they will not be able to run the entire width of the top due to the construction of the base. The underside suppports would lack about six inches from either end. Is there anything else I should do so that this does not happen again.