Ash table cupping - Router Forums
 
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post #1 of 8 (permalink) Old 01-25-2010, 07:41 PM Thread Starter
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Default Ash table cupping

I'm a weekend warrior woodworker tha just learned another valuable lession.

I made a kitchen table from ash. The stock was 5/4 milled to 4/4. AFter glue up and a week in the garage the top was flat. I used medium walnut danish oil as a finish and the plan was to top coat with poly. I brought the piece inside to fully dry the danish oil and the top cupped.

The stock was "kiln dried". I have some weight on the top to bring it slowly back to flat. My guess is the wood was too wet and dried unevenly inside the house.

After all the hours milling, cutting, glueing, sanding and and scraping the price of a moisture meter doesn't look too bad any more.

Keep you tool sharp!
Bob
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post #2 of 8 (permalink) Old 01-27-2010, 08:52 AM
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My recent experience is likely related, but I'm not sure.

A solid pine dining room table spent many uneventful years in our house... until I got the notion to cover the top with a vinyl tablecloth. Two weeks later, I noticed the table top had seriously warped. I removed the (air tight) tablecloth.. and the table top soon returned to normal. I think it has to do with the upper and lower surfaces being sealed to different degrees.
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post #3 of 8 (permalink) Old 01-27-2010, 07:59 PM
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Robert when you did your glue up did you alternate the direction of the annual rings . Since boards tend to cup in the opposite direction of the annual rings. This will balance the stress and keep the assembly from cupping at all. This applies to plain sawn lumber. Also the wide of the boards also could have some bearing on the cup. Try to work with narrower boards to make our blank for your top.
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post #4 of 8 (permalink) Old 02-03-2010, 10:35 AM Thread Starter
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Thanks for your responses. I did alternate the growth rings. I started with 30 BF rough, and after milling the wood ( 4 to 5 inch wide ) and selecting pieces I was forced to use two boards which were more like flatsawn, than quartersawn. These two pieces exhibit the most cupping.

The clamps and cauls helped to straighten the top, and none of my friends have noticed it is still slightly cupped.

If it was easy everyone would do it. Next time I check the moisture with a meter, and, add 10% to my BF estimate for the wood.



Bob
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post #5 of 8 (permalink) Old 02-03-2010, 11:14 AM
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Quote:
Originally Posted by Rob1 View Post
Thanks for your responses. I did alternate the growth rings. I started with 30 BF rough, and after milling the wood ( 4 to 5 inch wide ) and selecting pieces I was forced to use two boards which were more like flatsawn, than quartersawn. These two pieces exhibit the most cupping.

The clamps and cauls helped to straighten the top, and none of my friends have noticed it is still slightly cupped.

If it was easy everyone would do it. Next time I check the moisture with a meter, and, add 10% to my BF estimate for the wood.



Bob
Only 10%, Rob? I *aspire* to such tight tolerances!

How else do you keep the wood stove fueled on a cold winder day? <g>

Check out that new high-tech cordless router.. wireless and no recharging required!!
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post #6 of 8 (permalink) Old 02-03-2010, 11:50 AM
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Did you glue your top to the apron? Did you slot your mounting screw holes for top to allow for seasonal movement?

James
Whittier, CA.

Have a nice & safe day!
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post #7 of 8 (permalink) Old 02-08-2010, 07:00 AM Thread Starter
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I esitmated 10% extra when I started. I should have said add an additional 10%, total 20% extra to estimate.

I did not glue the top to the frame. I cut a dado in the rails, then fabricated "L" shaped wooded clips which are screwed to the top. This allows for movement in both the X, and Y axis. Its also easy to remove the top for transport.

Thanks for your responses.

Bob
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post #8 of 8 (permalink) Old 02-08-2010, 09:44 AM
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Bob
Sounds like a moisture problem to me. You could try putting bread board ends on it, might help.
Wayne
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