Tips for Cutting Foam on a CNC or CNC Machine

I'm always looking for cool new stuff I can do on a CNC machine. And one of the things I've been messing with lately is cutting styrofoam. So yes, this pink stuff is not jello. This is building foam from a home center, two inches thick. We'll talk about some of the advantages why this is cool, but lemme get going on a cut here. I've set up to do a 3D fish out of this foam. I've got a quarter inch router bit in the machine right now that's gonna rough it out. Then we'll change to a quarter inch ball nose. That's going to finish it so you can see just what foam cutting looks like. It's pretty cool stuff. The roughing pass is done. Bonus points if you can tell what this shape will be when it's all done. Roughing pass was done with a quarter inch up cut spiral cutter. I am running the bit at about 10,000 RPM. When you're cutting styrofoam we want to make sure the bit has the opportunity to cut, it doesn't start to burn. So 10,000 RPM is pretty good. My feed rate is just under a hundred inches per minute. So we're cutting pretty fast on feed, but lowering the RPM. Now I'm going to use a quarter inch ball nose and that's going to finish the shape out. So let's get that cut going. Dust collection is pretty important for this, that styrofoam builds up quite a bit of static electricity. So good dust collection is going to really help confine that the shavings coming off of it around two. Here we go. Who among you guessed fish? There it is all done. Isn't that cool. Now there's some products out there that allow you to coat styrofoam so it no longer looks like styrofoam when you're done. You can also paint styrofoam but you need to make sure you paint it with a latex paint. If you use a paint that's got a stronger solvent in it, it can actually melt the styrofoam. So do a little research on that before you're going to apply paint. But I think it's so cool that you can take a product like the styrofoam, cut an object out of it and get something that when you're all done looks nothing like styrofoam. So it's a great way to prototype projects. Practice your CNC work, it really does cut like a dream. It's not that expensive. It's worth experimenting with.