My Ender 3 V3 has started to underextrude on models that it has previously printed perfectly. It happens with whichever model I try, and with any PLA spool I load.
The extruder is getting fouled with filament dust. (Photo of dust on gears was after only a few hours of printing. There was lots more there the first time I opened it up.)
The filament grinding suggests an obstruction downstream (through the nozzle) or too much resistance upstream, causing the extruder to grind away as it tries to move the filament faster than it will go. After cleaning up the gears with a dry toothbrush, the gears look ok to me (see before/after photos) and they seem to turn freely.
I’m starting with dry filament (8-20 hours in the drier). Manually pushing filament through the heated nozzle gives me a straight thread with no curling, implying that it isn’t a nozzle clog, but I’ve switched out to a new unicorn nozzle anyway, just to rule out nozzle issues.
As for upstream resistance, I have confirmed that my filament spools are not tangled. I’ve removed the filament runout sensor that does add some resistance, but that has made no difference. The PTFE tube between the filament spool and the extruder shows no signs of internal wear. That’s pretty much the whole filament path, from spool to nozzle.
It is possible, I suppose, that the extruder isn’t gripping the filament tightly enough, allowing the gears to slip on the filament. I don’t know how to test for that, though, or an adjustment I could make to tighten the grip.
Heat creep could cause a partial clog so I’ve investigated the hotend cooling system. The fan mounted on the side of the hotend radiator does come on when the nozzle is heated. The onboard menu on the printer screen appears to call this the auxiliary cooling fan, which was defaulting to 50% (see 4th photo). I can’t adjust that during a print so i changed it in the Orca Slicer filament menu to 100% and re-sliced. Still getting the underextrusion.
I’m not getting any temperature error messages, and the onscreen graph shows steady nozzle temps. I’ve tried boosting my nozzle temperature from 210 to 220. Still underextruding.
I’ve tried printing it at half speed and still get the underextrusion.
What else can I check? I’d sure like to get this printer back in the game. Be