Shop-altered pushblock helps remove cup
Here's a way to remove one side of the cup in warped boards at your jointer. As shown in the drawing at right, a cleat added to a regular pushblock helps get the job done safely. To accomplish this, first flatten the concave side by face-jointing. Then remove the convex side of the warp by running it through your planer with the new flat side down. Be sure to take into account your reduced stock thickness in your project.
-- from the WOOD® magazine shop
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Some of that will depend on the grain orientation of the wood, and other factors, like species of wood. Some just react more than others. That being said, this will work for most boards in most applications. Remember to put finiah on both sides of the boards (amazing how many people don't finish the side that doesn't show, which will allow more moisture in.)
5/10/2012 10:00:45 AM Report AbuseThe cup may return due to humidity, However, it will be less due the board itself is more dry. As well, when a board is worked into a project, normally a finish is applied, which will reduce humidity effects.
4/7/2011 11:37:02 AM Report AbuseNo, not if you started with a piece of wood that was allowed to stabilize before you machined it. What you have done is flattened and thicknessed a stable piece of wood that will stay that way in any normal environment.
8/19/2010 06:09:59 PM Report AbuseAnd when the humidity changes, doesn't your cup return?
8/19/2010 10:51:00 AM Report Abuse