Extruder Cutting Filament?
Problem statement: extrusion stops midprint at random z-heights. Extruder drive gear is still doing it's thing, but the filament is just being ground to dust and is eventually cut all the way through because it wasn't feeding into the hot end.
This has happened on multiple filaments and multiple models. Some filaments are new, some are older. Some have been baked in a Sunlu dryer for 2 days before the attempted print. No cases of the filament being cross-wrapped or otherwise bound up on the spool. It does not happen on every print.
Have I got my idler too loose? Too tight? I just can't even with this problem. I've hunted for days trying to find examples of this. Either I'm using the wrong words to search, or this is a super unique problem, or is something so common nobody bothered to write about it and I'm just having one of those senior moments???
Any guidance that can be provided will be much appreciated.
Please and thank you.
RE: Extruder Cutting Filament?
I had a MK3.9 do it with PLA. See this post. So many variables, it is hard to find the key problem.
Still trying to figure it out. Next step may be to disassemble the Nextruder and check the filament drive gear for burs or sharp edges.
The ones I have seen haven't ground through, just broken. If yours is grinding through, try this fix for TPU printing, it might help. Maybe the idler isn't close enough? Remote diagnoses is just a guess.
If it is repeats on a certain print, submit it to Prusa. They will want the .3mf file.
RE: Extruder Cutting Filament?
I had a problem with some similarity namely the extruder filament drive gear was slipping against the filament and in doing so eroding it.
I eventually realised that I had made an error when assembling the printer. I had failed to carry out section "5.14 Nextruder assembly" correctly. I had missed out the step "Secure both parts with the socket set screw 3x25." This error meant that the idler was not supported at its pivoting end. In my case this error meant that the printer was able to print the first layer without problem but there was insufficient extrusion for subsequent layers due to lack of tension between the filament and the drive gear. Once the slippage started, then it rapidly got worse as the filament was eroded and the extruder ceased extruding.
Adding the missing set screw, then recalibrating the gear box fixed the problem.
I suppose the same symptoms could also be caused by having the two extruder tension screws too loose.
RE: Extruder Cutting Filament?
I have the same issue with my Mk4 Enclosure kit, I had 2-3 prints that the filament broke in the Nextruder, than all the other prints I made that where longer than 7-8h, the filament started to slip on the Nextruder gear. I tried different idler tension ajustement but nothing seems to work.
RE: Extruder Cutting Filament?
Same issue here. It broke 2 times with a Prusa Orange PLA filament which has lead to a cloggy noozle....
I Didn't encounter any issue with some other filaments (sunlu), so I tried another Prusa One and I am drying the PLA Orange one at 45°C for 4h and will see what will be the result. The issue occurs after several hours of printing, but I really think this is a filament issue which leads to this breakage. Will update the status of my testing in this thread.
RE: Extruder Cutting Filament?
With a Prusa Galaxy PLA no issue, print is OK. Drying is still in progress. Will do another test ASAP.
RE: Extruder Cutting Filament?
No more problem after dryng the filament.