Direct granules extruder V5.2: 3DBenchy

The video demonstrating a 3DBenchy test print.

About Extruder V5.2

Figure 1:
The extrudertube of version 5.2:

Figure 2:
At the upper end I made two notches with a round file that, together with a 3mm cut improves the entry of the granules into the extruder.

Figure 3:
Dimensional drawing

Figure 4:
I made and tested several variants of auger screw geometries. It turned out to be problematic that a small immersion depth, hence a short screws design, leads to nicely uniform extrusion, but the side effect is excessive stringing. This disappears if the screw is made longer, but then the print quality visibly decreases.

The problem is the lack of precision with the handmade extruder:
The deeper the screw goes, the more noticeable the not so good runout becomes, as sometimes more and sometimes less material is extruded while the auger wobbles around. However, if the screw does not go deep enough, the material will not be pulled out of the extruder during retraction.
A good base for the auger turned out to be a stainless stell wood screw with a diameter of 4.5mm.

Download

The 3D files and the dimensional drawing of the extruder are available as download package.

Sample print

I deactivated the software refinements "pressure advance" and "input shaping" that the Prusa MK4 offers during the current tests. When it comes to printing tests, it's still important for me to see what the extruder can deliver, without interference from the printer firmware.

Test print Benchy with Extruder V5.2, Starbaord

Figure 5:
3DBenchy:
Layer height: 0.2mm
Nozzle: 0.5mm
Extrusion width: 0.5mm
Print time: 55min
Dimensions: 60x31x48mm
Material: PLA Powder, grided from industrial PLA pellets

Test print Benchy with Extruder V5.2, Bow

Figure 6:

Test print Benchy with Extruder V5.2, Portside

Figure 7:

Test print Benchy with Extruder V5.2, Tail

Figure 8:

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