Milling styrofoam board enquiry

Howdy,

I'm just running some test milling forms in blue styrofoam board. I am making lost foam masters for aluminium casting.
I'm running cut tests on a low relief model (150mmx150mmx40mm). I'm using a 8mm OD rasp bit to rough out and using a 2mm OD end mill to finish. I run both at a feed rate of about 2 cm/sec but the spindle on its slowest RPM (approx 11000rpm). This combination seems to give me the best results.

However I see that the final finish is still quite hairy and the rasp sometimes still gets too hot/ and or melts the styrene. Are there some know techniques or bits for working with styrene I should try? I think i'm pretty close but just wondering if there is anything I can tweak.

Thanks

I use downcutters with some success on blue Styrofoam. Both in 8mm and 2mm. But lately broke the 2mm on another job and looking for a re-source should you find one?
The finish was marginally better and surface stringing much better. Not to the same degree as wood downcutting, as you might expect. But for me better!

Thanks. I bought a couple of 4 flute upcutters recently but your right I should try a new sharp downcutter to compare. Looking at the endmills specifically sold for polystyrene and foams lots of them are upcutters but what i am adviced is to run these bits below 6000rpm so just about to see how my spindle, which currently has a minimum of 12,000rpm likes running at half that.

Try doubling your feedrate.

Quote:

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Originally Posted by Leadhead

I use downcutters with some success on blue Styrofoam. Both in 8mm and 2mm. But lately broke the 2mm on another job and looking for a re-source should you find one?
The finish was marginally better and surface stringing much better. Not to the same degree as wood downcutting, as you might expect. But for me better!

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https://www.sorotec.de/shop/Cutting-...l/2-Flute-366/

Rob