Direct Granules Extruder, FDM prints from powder

It was a long way from the early prototypes in 2021 when the Hackaday Prize triggered the project, to a working 3D printer that converts plastic powder from failed prints into something new:

...but still not finished. I am currently working on a 3D printed gearbox for the extruder motor.

With the converted Prusa getting closer to my everyday 3D printer, I need more raw material. I modified a commercial mill to a grinder with integrated sieve. The material throughput I get is definitively good enough, however there are still some things to improve:

The granule printer meanwhile works very well and I start doing more than just print tests and with that the weak points can be seen. I have to replace a too weak gearbox and must redesign the powder feed.

I have modified the mechanics of the Prusa again. This time I had an eye on better usability of the printer. Furthermore I am working on the automatic material feed. The parts needed for this were all printed from PLA powder. The machine gets closer to a printer that is almost like a _normal_ (filament) printer:

The full print of a small part is demonstrated in another video:

The load cell of the Prusa MK4 is implemented and so bed leveling works fine. Now that larger prints can be carried out, I have made a Benchy:

If you know a granule FDM printer that can make better looking Benchies, leave a comment!

I got some PLA powder and trying to print with this raw material didn't work with version 5.0 of my granule extruder. I had to shorten the extruder tube (again) and make some more changes to the hardware, but now printing with the powder works:

I am in the process of converting a Prusa MK4 to granule printing. Part 1 of the process shows how to build the core component, extruder V5.0 and first test prints:

The simplest component of my granule extruder must meet certain criteria to get a working 3D printer:

Next step: Converting a Prusa MK4 to direct granule printing.

I have been shrinking the tube of my extruder in order to reduce friction and so to get a better retract:

Version 4 is made of a brass / stainless steel tube and has of course a simple wood screw an auger:

A 20 minutes test print of a tiny 27x25x12mm track link shows the capabilities of the new design: