Filament stoped coming out and I cannot pull it out  

New Member

Been using MK3s for 1days now, I printed around 10 first layer test and one whistle from SD, Everything was fun and dandy until just like hour ago. I downloaded STL from prusa prints, imported it to slicer, used default setting for mk3s+prusa pla (which was budled with printer) got g-code, transfered that to sd and push print. It was 4h print and just after 2h I notice that nozzle was a bit higher than the model on plate and the filament wasn't coming out!!!

I pause the print (dunno why? what hoping I could somehow saved the print?) and tried to unload filament but without success. Then I stopped the print. Want on pc to look for solution, then went back and tried unload few times, and nothing.

I found method to set 260C for PLA and after 2minutes use needle (that was bundled with printer) insert it in nozzle for not more than 1cm. While the nozzle was getting to 260 I notice a bubble forming from nozzle (small bubble a little bigger than the hole in nozzle), at 260C i waited 2minutes and insert needle for not more than 1cm.

That didn't helped a bit, I tried 2 more times, I tried to move needle abit, It took a bit of filament out on needle but not much. I then tried to unload filament, but still the filament is stuck there hard - I felt like I could lift printer by that one filament string.

I did read that those thing does happens, especially with cheaper filaments (but Im using the prusa silver, and bougth other prusa spools for future) but I wasn't ready for this to happen on my second real print.

I'm hopping I wont have to disassembly the extruder. What do I need to unclog from this situation ? Pushing filament in and out from extruder doesn't make it move, nothing is coming from nozzle.

Should I somehow unscrew nozzle, boost temp to 260C again and hope it will start dripping ? or is it somehow stuck in tube and expanded and there is now way to unclog it without somehow disassebly whole extruder?

Posted : 11/06/2020 11:38 pm
Noble Member

The one time this happened to me, I let it sit with the nozzle at 255C for maybe 20 minutes or so, then probed with the thin acupuncture needle, and then did a more or less normal load of the filament and it started extruding again.

Posted : 12/06/2020 12:43 am
New Member


Thank you for responding. I end up few times on Support Chat. I tried 260C  - that information I found on prusa page, but the Support Chat said 280C for even 5minuts, while I was waiting they said to pull at around 1minut in. That helped, then I was instructed to Cold Pull 3 times, and after then I tried again and it clog again. Also I notice filament sensor not working correctly - supported said to use washer/cut the plastic but I also asked for replacment - this is my first printer and I would like it to be the most stock at begginig as I can - in case future mods (which could not fit with custom part/washers).


I clog again, unlocked same way with help of support, pulled 5 times, replace tube and still no luck. But the third support person said that hotend replacemnt will be send so It looks like I was super unlucky.

Good thing the support is helpful and that there is warranty/replace program.


Posted : 15/06/2020 5:23 pm
Active Member

@michal-poland hi ive had this a few times- check to see if filament is stuck in the gears- if so remove the tension screw on l.h.s. of mot0r take note of the number of turns to remove screw and spring.  if you cannot pull filament then remove the gear housing screlocated at at back of extruder a which holds the tension gear( the hole where you can see the gears.With this gear and holder removed check for filament-you might see filament.if so then remove the drive motor it will come out with the gear attached and may be a little hard to remove,especially if filament is stuck to gear -if filament is stuck on gear try prize it off with tweezers etc. you might then be able to remove filament a cold pull

If filament breaks just where the filament is above the xtruder -below the gears  then what i  do is- i have a steel rod 0.35mm thick  put the temp upto 285c and put pressure on  the filament this has worked several times for me- the filament oozes out of nozzle eventually -use a 0.4mm needle up the nozzle to help clear some bits every 30 secs when clear the needle will push steel rod. reaasemble when complete.I put a light smear og grease on bearing for gears and a very very small smear thermal paste on motor housing,

good luck

Posted : 17/06/2020 2:07 pm
New Member


Sadly no, I checked gears 3 times after each clog, they grind filament out because the filament is stuck somewhere inside hotend.

Yeah bumping temp as high as you suggested did the trick few times. But according to support its faulty hotend.

Posted : 17/06/2020 4:51 pm

Please Login or Register