Heads-up: Not all cheap insulation foam is created equal!

After running some test cuts in cheap insulation foams, I have noticed a substantial difference in cut-quality between the different foams available from my local Lowes/Home Depot.

The Green extruded stuff (from Lowes) that I have in 1" nominal thickness is considerably softer and doesn’t chip as nicely as the pink 3/4" nominal thickness pink foam that I’ve gotten from Home Depot.

I had both laying around from some model-making and garage-insulating projects, and just figured I’d point out that the pink stuff is way better for Nomad use.

It’s considerably more firm and has a tighter grain structure.

I’ll post some pics once I’ve cut a few sample pieces in the pink stuff here.

Here are a few pictures of the results in the 3/4" pink foam from Home Depot vs. the 1" green foam from Lowes:

I did some further examining on the stuff I’ve got, and I think that thickness is an important part of the quality you’re going to get as well, as the thicker stuff tends to be “fluffier”. It’s probably better to take multiple sheets of thinner 1/2 or 3/4" foam and glue them together with an appropriate adhesive that won’t eat the foam rather than use a thicker foam sheet, if you’re looking for cheap material to do test-runs in. Also the pink is just better texture for cutting, regardless of which one is better insulation…

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Hey @UnionNine,
Would you mind posting what settings you use to mill the pink foam, please? I just got some and am curious how fast I can go.


Hi @UnionNine, sorry to bug you about it but any chance you can post your speeds and feeds etc? I’m starting to work with this stuff now and any suggestions would be very welcome.


Hi Mr Hume,

I’m slowly emerging from a work-induced stasis on forum activity—and catching up on these kinds of things :blush:

If you haven’t found out yet, basically you want to run a fairly aggressive chip-load at a fairly high speed in foam—I’d say depending on density between 50-60ipm at 6krpm with 1xdiameter by depth is a decent starting point for roughing, just off the cuff. you should slow finishing passes down a bit because you don’t want to deflect the foam too much since it’s relatively soft, all things considered.

Also, make sure you have it well anchored so that the foam doesn’t get pulled up/out of your clamping arrangement, since it’s got a fair bit of flex.

I realize your last post was 10 months ago, but thought I’d mention that XPS foam comes in different densities and that might contribute to this behavior.