I've got a secondhand Renkforce RF1000 which I can't seem to get working properly. Initially, I asked about hardware issues that required fixing. After fixing those I still got some inconsistent printing results. These problems got worse with a new nozzle and new filament. I've now narrowed it down to one problem: bad feeding
- I've got a secondhand Renkforce RF1000
- I print using 2.85 mm PLA
- I've got a new 0.3 mm nozzle
- I've got new springs for holding the filament against the extruder
The feeding mechanism
The problem seems to be that the pressure for extruding filament through the nozzle is too high. This causes the grub screw to keep spinning without extruding filament. So in the picture, the left screw will spin and the right one will remain stationary.
This isn't consistent, it might work for a few millimetres and then stop working for a bit. It can cause the screw to grind into the filament creating a hole that cuts the filament in two.
Here's what I've done to try and fix it:
- Cleaned the nozzle with new 0.25 mm needles
- Cleaned the nozzle with acetone against ABS that was stuck
- Did a few cold pulls to confirm there's no filament stuck in the heater.
- This wasn't the case and when removing the nozzle I could easily push or pull filament through.
- Tightened and loosened the screws holding the filament against the grub screw
- Too tight causes clicking or more grinding. Too loose causes the filament to just not get caught at all
I'm out of ideas of how to fix this. Any help you can give is greatly appreciated.
EDIT: here are some video's extruding 50 mm of filament at 2 mm/s and 10 mm/s
2 mm/s (both links to imgur, didn't manage to get the video inline)
I replaced the driving gear and replaced the new nozzle with an old one. I'm not sure about the size of the old one but I assume it is 0.5 mm. I calibrated the extrusion and tested at 1 mm filament per second, I now get the exact results. However, when printing two 20mm calibration cubes I get quite bad results. The first cube (left) is printed at a 1.0 extrusion multiplier and the second one (right) is printed with a 0.95 extrusion multiplier. Any idea what these quality problems are caused by?
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