Two-Material Switching Feeder

There are a several good options for multi-material units:

  • ERCF
  • SMuFF
  • 3D Chameleon
  • Trad Rack
  • Bambu AMS
  • Prusa MMU
    and probably several others. However these all seem somewhat expensive (~$200+) and complicated. They also seem to target serving 4 materials and expand upward from there.

A simple two-material switcher could enable

  • two-color printing
  • disolvable supports
  • same color spool switching on run-out
    and would serve the vast majority of my anticipated use cases.

Limiting the design to 2 material potentially simplifies things - and I am embarking on at least a thought exercise for a KISS (keep it stupid simple) switcher.

So far I have compiled what appear to be 3 or 4 viable avenues of pursuit:

  1. use one drive stepper and a 5mm shaft extension that passes through 2 (or more) direct drive extruders. Add 1 solenoid to engage / disengage each tensioner.
  2. use one BMG extruder, stepper and solenoid for each material (x2).
  3. use mirrored BMG extruders, 2 solenoids and a single dual shaft extruder.

I found an implementation of concept 2 on GrabCad:
It includes an integrated spool management section which is beyond my initial Scope-of-Work, but it looks like I can just print the feeder drive section and check fitment / function.
At the very least it give me some hardware I can start to try to configure firmware for.

There are several options for firmware, but Happy Hare looks like a good place to start.

1 Like

Only been using it for a few days now, but Happy Hare has been great so far. There is a LOT to it and a LOT to set up. But it seems to work (and learn) really well.