"spaco" wrote:

I just heard of a woodworking machine called a "Flattener" today.
We were at a birthday party and I asked for advice about taking
the twist out of a 9/4 walnut board, 8" wide and 5' long, without
having a jointer big enough or using winding sticks and hand planes.
Obviously, the task is to get one side of the board flat, and then
go from there to get parallel sides.
snip

Can't help you with the "Flattener", but based on the size and weight
of the piece, think I would head to the commercial drum sanding shop
rather than trying to use a bench thickness planer.

A few passes removing a short 1/32" per pass and you should start to
see how much of a problem you face getting flat surfaces.

Lew