Creaking + Underextrusion
I have had my CoreOne for about a year now and it has worked flawlessly up until 3 months ago. I use this for work, and it had started to under extrude right before I took paternity leave (about two and a half months ago). Not a lot, just a few mm per layer. Enough that I could not send the product out if it was being paid for though.
Evidently the issue got significantly worse after I left. Constant under extrusion, or just pauses in filament feeding where no filament left the nozzle for 5 or more mm. When I returned the issue was still present, and the staff member who tried to 'fix' it was no longer with the company. From what I gather, he at LEAST messed with the idler tension. I found that the gears were grinding, as if spinning on the filament without pushing it.
Where I'm at with it:
- I have relubed the planetary gears without removing them, performed a gearbox calibration, and inspected all gears to look for any damage.
- I replaced the nozzle with a brand new nozzle, same type as the previous
- I have tightened the idler screws, which increased the under extrusion and resulted in a clicking noise from the gear.
- I massively loosened the idler screws, to the point it seems wrong, like, they are barely in the latch, this helped significantly
- I've opened the idler door and inspected both the bearings and the feed gear, both appear fine. The gear is intact (no nicks) and the bearings roll freely.
- All prints are using the exact same bgcode I had used previously without issue.
After loosening the idler screws an insane amount, the problem is mostly gone. I occasionally hear a creaking from the extruder though, and I'm uncertain where it's coming from exactly. The noise was not present before the issue arose. Every 3rd layer or so, I still get a few mm of underextrusion where no filament comes out at all.
I work as a technician, and this still feels wrong. The idler screws were not this loose before, and everything on the prusa site indicates they should be flush with the holes. This feels like a fix that is compensating for another problem I'm not yet seeing. I'm out of ideas at this point and have looked at every bit of information I can find. Does anyone have any ideas what would cause underextrusion in the first place? Or what super loose idler screws might compensate for?
RE: Creaking + Underextrusion
What kind of filament are you printing? This seems like heat creep caused by a dusty heatsink or a defective heatsink fan. Perhaps start by disassembling the heatsink and fan then use compressed air to clean it out.
RE: Creaking + Underextrusion
If you haven't printed the gearbox alignment tool, I'd do so, as I'd want to take it completely apart to look for "stuff". I'd also pull the Bowden tube from the Nextruder and just see if filament can be pushed/pulled smoothly from the spool without due friction.
RE:
The idler screws were not this loose before, and everything on the prusa site indicates they should be flush with the holes. This feels like a fix that is compensating for another problem I'm not yet seeing.
The more I think about it, the more it seems like a heat creep problem. If the filament was softened by heat creep, then normal tension on the idler bogie could possibly squash the filament into an oval shape and it would no longer fit in the nozzle tube. So by loosening the idler screws you temporarily solved the problem. With the normal tension, when there is a blockage, pressure builds up and eventually forces through the filament.