My Cable Robot CNC Foam Cutter is running!

Hey kind folks,

I thought I’d share a quick video showing the status of our Linux CNC foam-cutter project. I’m brand new to LinuxCNC and basically just took this on as a fun project to learn a bit. 

photos.app.goo.gl/ksw5mnEoJEibSiqs5

The drive drums are custom designed 3D printed hypocycloidal drives running a pair of cables to a hot wire knife.  The 3D printed drives are a bit janky but actually work surprisingly well.  Not sure how durable they’d be in the long term. 

While this test-bed is quite small, the objective is to be able to mount the drum modules on a wall some 12 feet apart and in doing so be able to cut shapes out of large foam sheets. The objective is to be able to build an ultra-low cost CNC foam cutter for less than $200.  I could then manually stack the cut sheets together like a loaf of bread and build very large 3D printed objects ala a huge FDM (albiet with 2” thick layers).

Given the lower speed we’re running the unit on a Raspberry Pi.  I’m sure the latency is a mess but it appears to be tracking.  The forward and inverse kinematics functions were the majority of the challenge - I made life much more difficult by running the cables tangential to the drums instead of through a fixed ferrule but I was eventually able to solve the kinematics.  The inverse kinematics were just trig but the forward kinematics required numerical methods (Newton-Raphson) which I only sort of understand but seem to work.

More to come to make this more useful. If there is any interest I’ll likely open-source the whole thing when it’s a bit more stable and refined.

Thanks to all of you who helped on here through my rough patches. 

Very cool.