In article .com, wrote:
Hi all. A chessboard I had made for me is quite bowed, and I'd like to
fix it. It is big though--almost 22" square. The stock is thick enough
that I think this could be corrected.

I think your first step ought to be to talk to the guy who made it for you,
and see what he can/will do to fix it.

Can I find a planer at a furniture shop so big? Otherwise it looks like
a lot of sanding is in my future.

Possible, but somewhat doubtful. You're *much* more likely to find a cabinet
shop, or hardwood dealer, with a thickness sander wide enough to handle that.
Post your location here, and I'll bet somebody chimes in to tell you who to
contact.

You probably don't want to plane it anyway. Chessboards are usually built with
the wood grain in the dark and light squares mutually perpendicular, like
this:

||==||==||==||==
==||==||==||==||
||==||==||==||==
==||==||==||==||
etc

and no matter how you plane that (except diagonally, in which case you'd need
a 30" planer) you're going to get some tearout. A sander avoids that problem.

Probably, it will be necessary to shim it on the bottom side as it goes
through the sander, to keep it stable and level. After one side is sanded
flat, turn it over and sand the other side too. Try to remove an equal amount
of wood from each face; otherwise, it's likely to cup again.

Once it's flat, you should use a random-orbit sander to remove the ridges and
grooves left by the thickness sander. I'd start out with 100-grit sandpaper,
then 150, and then 220. Apply the finish of your choice, and you're done.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?