I’m in the process of getting started with cutting foam with a router.
My goal is to do a lot of 3D milling.
I still need to get some bits for my Makita, and I was just wondering if anyone has done this using hot wire cutting tool type thing.
It seems like it would be a really good approach for this kind of work if I am not mistaken.
Thoughts?
Not sure if this is the kind of info you’re looking for… not 3D milling. But hot-wire cutting of foam is certainly doable…
Nice, thanks!
Certainly looks like very strong evidence that I’ll be able to achieve the type of work I am looking to get done using a hot needle strapped on to my MPCNC!
I realize that you may be wanting to 3D-mill foam with a router to eventually move to 3D milling/carving wood. And you haven’t mentioned the foam you want to cut/mill… I personally like the construction foam “Foamular” from HD.
But, for fun, if you loosen your definition of “hot needle” to include “laser” you can get 3D on the non-white Foamular stuff (not white styrofoam) as well…
– David
Back before covid, I was doing some cosplay props for my daughter and her friends. I build a couple of manual hot wire foam cutters and explored the idea of a CNC version. My first thought was an attachment for my MPCNC. Here is a tool that came with a kit.
I’ve used the other tools in the kit but not this one. Assuming it gets hot enough to avoid deflection at reasonable speeds, it could be mounted on an MPCNC. The issue is that I don’t think there is any benefit over using a router bit. Theoretically it could cut through thicker foam, but I’d need a really tall MPCNC. Right now, if I need thicker, I just cut multiple thinner pieces and glue them together. And I much prefer dealing with the “dust” from routing vs. hanging around with the smell of melted foam.
As for dedicated rigs, I found 4-axis machines most interesting. This is an Instructible for one such build. Here is plane wing cut with a 4-axis machine. Notice how it tapers from one side to the other. This shape could be routed out using double sided milling, but wire cutting is much faster and cleaner.
I’ve also seen both manual and “automatic” rotary attachments for 3-axis CNC hot wire cutters that can produce multi-sided and round foam objects.
For 4-axis and “automatic” rotary applications, the elephant in the room is authoring. There isn’t much out there for authoring, and “free” solutions are almost non-existent…at least when I looked a few years ago.
I’m looking to do foam that can be used to make casts for concrete or sand cast aluminum or maybe just wood at some point but that’s still pretty cool that you can do that with a laser.
One reason I was considering heat tool was due to the silence of it, but yes – ventilation would be important.
Thanks, that’s a lot of info to look into.
I had the same concern about the noise, my “workshop” is a spare bedroom in an apartment … and to machine surfboards there’s a lot of material to remove.
But i tried regular with regular end mills (6mm and 10mm dia) and the noise wasn’t bad enough for my neighbors to complain, the one above told me he didnt hear anything, and i couldn’t catch the one below to check, but no complains… yet.
I’m milling low density polystyrene (17kg/m3), XPS (i think 25kg/m3) and some close cells PVC foam (75kg/m3).
One of the key for less noisy operation is to use a spindle instead of a router. I use that one : https://www.amazon.com/dp/B08N61JPXT?ref_=pe_386300_442715960_E_406_dt_1
As i’m milling up to 100mm down into the material, my machine is not extra rigid (135mm Z axis) and chatter is sometime an issue, usually solved by playing with the speed or depth of cut… for some reason, full 100mm depth with 6mm overlap with a 10mm cutter tends to created some chatter 
. Chatter definitely makes the noise worst.
The other source of noise i had to deal with is the “skin” on the XPS panels I used, very annoying.
Good luck!
