FYI: 2 inch Ultraboard

[diapowder2000]

I've used Onsrud #52-367 to cut 2inch Ultraboard.
13 letters of 29inch(H) x 33.5inch(W).
#52-367: double edge, upcut spiral, solid carbide.
(CED: 1/2 CEL: 2 1/8 shk dia: 1/2 OAL: 4 inch)
I also bought #40-562(Foam cutter, OAL: 6 inch)
but I did not use it as I have to cut off at least
1 inch of shank to fit into Porter router.
Anyway, It worked out quite all right. I've tried
2 passes at 1.015 to cut through 2inch board(15000rpm) and
placed vacuum formed plastic sheet on top of my MDF
spoil board(as Jerry Hicks suggested: Thks Jerry).
Actually I tested cutting without ultraboard on
the table and was able to see bit working on the surface of plastic sheet.
And I sanded edges with 220mesh Norton.
There were a lot of chips left at the bottom of the table when I picked up the letter after cut.

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[diapowder2000]

And main difference between Ultra Board and Gatorfoam is material of face of both sides of
board.
The face of Ultra Board is .015" polystyrene
while those of Gatorfoam is wood-fiber veneer.
The core is the same material though, extruded polystyrene foam.