Two choices, Delta or Performax.
Not the only choices but they are units that would seem to fit your needs at
a reasonable price. The other choices would be much larger and probably over
These units use a wide abrasive belt on the table to move stock under the
sanding drum and !MAY! allow the use of some sort of jig to allow you to
vary the thickness. Off hand I can't think of how but you have a better shot
then with a planer.
I wouldn't hold out much hope though if I were you. The units are designed
to take something with a flat bottom and sand the top parallel too the
bottom surface and make it smooth.
They are not really meant to remove stock and thickness it, but rather to
provide a near finish quality surface. They do not perform this function
especially fast either.
Try to force too thick a piece of wood stock through and they stall. In the
case of foam I would guess that the sanding drum would just crush it.
The only real way I could see it actually working for you would be if you
were making multiple passes and manually lowering and raising the sanding
drum as the piece passed under it.
But, who knows maybe you could get it to work somehow. About the only way I
can think of doing it efficiently would be designing, building, and
reengineering the unit to be computer controlled.
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