The problem with 3D printing multi-colors using a single nozzle is that it poop a lot. Every time they change filaments, they’ve got to purge the single nozzle, which results in a huge number of technicolor “purge poops” which on some machines are even ejected out a chute at the back of the printer. They almost write themselves.
What’s not a joke, though, is the sheer mass of plastic waste this can produce. [Stefan] The following is a list of the most recent and relevant articles. CNC Kitchen It was possible to produce more than a kilo worth of printer waste for a multi-color 500g print. He then set out to find a way to convert printer poop back into filament. The results were quite interesting. The tests are based on a 3Devo Composer filament extruder that is used in a commercial laboratory. But they can be applied to any filament, including home-brew extruders. A few important process tips became obvious very quickly. The first thing to note is that purge poops were too large and stringy for a filament extruder. They had to be shred.
Second, everything needs to be very clean — no cross-contamination with plastics other than PLA, no metal bits in the chopped-up plastic bits, and most importantly, no water contamination. [Stefan]’s first batch of recycled filament came from purge poops that had been sitting around a while, and sucked a lot of water vapor from the air. Purge poops that were hot and fresh after a print job worked best. Again, ick.
[Stefan] It took a while to find a good process that would produce filament that was usable and not jam the printer. The color was also pretty good, but that depends on what colors you use to begin with. Granted, not everyone has access to a fancy filament extruder like his, so this may not be practical for everyone, but it at least shows that there’s a path to reducing the waste stream from any printer, especially multi-material ones.
