Warping after planing

Causes for the warping of boards after they are planed flat. June 13, 2001

Q.
On occasion, I have experienced warping after jointing a board dead flat and running it through the planer. The jointed board stays flat for several hours but warps as soon as it is planed. This has occurred with oak, maple and pine. Any thoughts?

Forum Responses
I suspect this problem is caused by incorrect drying which is building stress within the wood. This stress is then partially released when you machine more from one face than the other.

Read up on doing your own stress tests by drying a sample piece in an oven. If it is a problem, you will need to go back to your wood supplier.

You could minimize the problem by planing off opposite faces more equally.

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You may not be letting the lumber acclimate to your shop long enough. It's best to let the wood sit in the area it will be worked for at least a week, two if possible. This relieves the wood movement issue.

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I agree with the above. I have seen problems of warping caused by improper drying many times. This is one of the most common problems with warping.

I have also experienced warping due to lack of time to allow the wood to stabilize to the conditions. This is most common during the extreme hot or cold times of the year.

To reduce the warping, remove consistent amounts of material from both the top and bottom of the material. This may help.

Dave Rankin, forum technical advisor