Replies

1. 
   RalphBarker | Mar 17, 2010 02:36am | #1

   Sounds like they were surfaced on a jointer, using improper technique. To run them through a planer/thicknesser, you'll need one flat reference surface - i.e., no twist. Removing the dual taper can be done either with a planer or with hand planes. Hand planes may be better if the taper is too extreme, though. Make sure that what you'll have left is of sufficient thickness for what you want to build.

2. 
   flairwoodworks | Mar 17, 2010 10:18pm | #2

   12" long, eh?

   12" may or may not be long enough to go through the planer.  It will vary from planer to planer - ultimately, the board must be as long as the distance from infeed roller to outfeed roller.  On my Dewalt DW735 13" planer, that distance happens to be 13" if I recall correctly.  Now as I believe Ralph mentioned, the board needs to be evenly supported from below to flatten the board, otherwise the rollers will just press the board flat, the cutterhead will remove some thickness, and when it comes out, the board will spring back to it's warped shape.

   Personally, I'd use a hand plane.  If the boards are only slightly warped, the right joinery might be enough to pull them flat.  But that's not good practice.