Hello all,
I have had Prusa MINI for a few years already and I have printed PLA without an issue but recently I have printed only PETG for some time I got through multiple spools of PETG without any print in PLA. But after I tried to print PLA my extruder kept skipping and grinding filament and when I tried to feed filament by hand it went easy for a little bit but after that, it went very hard as if the filament was cold so I tried to bump up the temperature to 235C and it helped a little bit but on faster sections of print like the infill extruder is skipping again. I don’t think I have unreasonable speeds i am using a standard Prusament PLA profile with Prusament PLA. I have also tried PLA+ from some different brand with the same result. Then I changed the nozzle from an E3D hardened steel nozzle with nano coating to brass (not new I have printed PETG on this one as well) still with the same result. PETG is printing fine. Is there something I can try, please? I am out of options.
You probably have a petg jam higher up in the heat break.
Take the Bowden tube and nozzle off and see if you can use some filament or a needle to clear the jam.
I tend to also think you have some kind of petg clog in there. Can you still print PETG just fine?
My best guess would be that you have some petg left in the nozzle that for whatever reason isn’t being melted and pushed out, what you could try is doing a cold pull
If you haven’t done it before, you basically heat up the hotend, feed in some plastic, then you turn off the heat and let it cool down until the plastic is partially hardened, then you yank on the filament
If everything goes right, the plastic down in the nozzle will be yanked out, and pull with it any impurities, leaving the nozzle clean and unclogged
Alternatively buy a new nozzle that you only use for PLA, i have heard a lot of people having issues like this when switching back and forth with the same nozzle
Yes, I have tried that but it didn’t help then I tried to burn away everything in a nozzle with a flame so the nozzle was very clean and I think it helped a little but after a few minutes of printing PLA, I still heard grinding of filament.
just came to my mind that I can try to check ptfe tube that goes to hotend I know those are a bit sensitive to heat even tho in Prusa Mini the tube shouldn’t be in a melting zone but mine is very old. It is the one that my printer comes with so maybe I should replace it. I will update you guys if that is the case.
You’ve got a jam. Filament is dried and burnt up in there. PETG is a lot more fluid / lower viscosity when hot, so it’s flowing around the crusty. Take off nozzle, remove PET tube. You should have another PET tube in the spares bag that came with the printer. Clean out the extruder well.
I did have nozzle cleaned but my ptfe tube is totally melted and i lost the spare so i flipped it and it did helped a lot i have managed to print something without a fail but still only at high temperature 235C so i had a lot of strings so tomorow i will try to find the replacement i hope it will fix it
Purge some pla at higher temp than you print petg at, or even better use different nozzle for pla. If hotend and ptfe tube are clean try changing tension in extruder spring. Unlikely, but wrong tension can also cause grinding
AFAIK the Prusa Mini does not have a tension spring, but maybe the extruder wheel is dirty?
Thanks for the tip the extruder wheels were dirty from all the grinding but there is a tensioning spring and i have it quite loose because i had an issue with PETG because i have my printer in enclosure and with bed at 80C in enclosure was so warm that my filament which is inside the enclosure as well was so soft that extruder squash it a little bit and it git stuck inside that longer ptfe tube which is between extruder and hotend
