Accidentally melting pink foam

new one today. happened twice now.

milling pink foam. foam is melting.

i’m not running a roughing pass. just finish. so the bit is dropping straight into 1.5 inches of foam. i just trimmed my feeds and speeds to 100 in/min cut feed and 50 in/min everything else. could it be going too slow. ?

i know i should be using the feed rate calculator - and i will - but has anyone else seen this? got any advice? earlier when this happened i was running at 300 in/min across the board - but the bit was dropping down into a lot of foam and it might have been running slow at that point. so there are some similarities.

interesting if not so scary. glass like material. clearly the odor is not to be encouraged. wicks around the bit like candy floss. i can see how this stuff on fire is really really really to be avoided at all costs. just nasty stuff. the big hole looking thing is the bit spinning with a glob of foam on it. ugh. :confused:


1 Like

ok my CNC guardian angel sez too slow. so i’ll test that theory and boost everything back to 300 in/min and up the spindle speed too


Definitely too slow!

I should note here: That pink foam isn’t healthy! Be sure you have adequate dust collection + filtering + PPE.



We have some notes on foam on the wiki:

650 for the speed and 5mm depth per pass though. I had my dw611 set around 3 for the speed

(from: )

Owens-Corning “Foamular” project boards: 125 iPM and 0.35 doc. 1/4" 2-flute straight bit


yes. i have Hepa shopvac, dust devil, n95 mask etc. i feel pretty good about my setup for collecting particulates but it’s the melty melty that freaked me out. :smiley:

edit - but i’m always up for suggestions on best practices. i’m about to switch to a powertec dust collector with a less than 5 micron bag, and to use the Hepa shop vac for general cleanup here in the shop.


i’m back to 300 IPM and between 3 and 4 on the dewalt spindle. seems to work nicely.


curious though - what is considered a healthy material to mill?

i’m mostly using pink foam out of convenience and naivety on my part.

i need something that holds details fairly well, isn’t crazy expensive and won’t take all day too mill. but beyond that i am open to not milling pink foam or ever having it in my life again for that matter.

  • oh and i plan to upgrade to 3M P100 particulate filters. i just keep forgetting to bring it to the shop. i figure that should remove most all little things floating round the shop while i’m milling.