The elemental drawback with multi-color 3D printing utilizing a single hotend is that they poop an terrible lot. Each time they alter filaments, they’ve obtained to purge the only nozzle, which leads to an enormous variety of technicolor “purge poops” which on some machines are even ejected out a chute behind the printer. The jokes virtually write themselves.

What’s not a joke, although, is the sheer mass of plastic waste this will produce. [Stefan] from CNC Kitchen managed to generate over a kilo of printer poop for a 500-gram multi-color print. So he set about on the lookout for methods to show printer poops again into filament, with attention-grabbing outcomes. The assessments are based mostly round a industrial lab-scale filament extruder, a 3Devo Composer, however ought to apply to nearly any filament extruder, even the homebrew ones. A couple of course of ideas rapidly grew to become evident. First, purge poops are too large and stringy (ick) to feed straight right into a filament extruder, so shredding was mandatory.

Second, every thing must be very clear — no cross-contamination with plastics apart from PLA, no steel bits within the chopped-up plastic bits, and most significantly, no water contamination. [Stefan]’s first batch of recycled filament got here from purge poops that had been sitting round some time, and sucked loads of water vapor from the air. A therapy in a heated vacuum chamber appears to assist, however what labored finest was utilizing purge poops sizzling and recent from a print run. Once more, ick.

[Stefan] ultimately obtained a course of down that produced respectable, usable filament that may jam the printer or lead to poor print high quality. It even had a fairly good coloration, which after all is completely depending on the combination of colours you begin with. Granted, not everybody has entry to a elaborate filament extruder like his, so this is probably not sensible for everybody, nevertheless it at the least exhibits that there’s a path to decreasing the waste stream from any printer, particularly multi-material ones.