MK3 filament not extruding
Hi all. I have a Prusa MK3 that I have used for years and love. Recently I developed a problem where the printer is extruding very thin filament to no filament. My thought was this was a clog of some type and so I got to work. I performed multiple cold pulls and that didn't work. I inspected the PTFE tube and it is clean and clear. I replaced the heat break and the nozzle and that didn't work. At this point, I feel like I can say the head is clean and clear. Could the problem be in my extruder? I have played with tightening and loosening the screws for the gears with no such luck. I have never noticed it before but the gear on the door for the extruder is extremely stiff (doesn't move at all while extruding). I have tried to remove the pin that holds it to inspect the gear but I have had no luck. Any thoughts/suggestions are greatly appreciated.
RE: MK3 filament not extruding
Hi John,
It seems likely that a seized idler gear would prevent the extruder from properly feeding filament. My guess is the frozen gear is acting as a brake and effectively locking the filament in place.
I built an MK3S+ from a kit so my kit may be different from yours but I’d bet they’re similar in design. The idler gear has two needle bearings inside that run on a shaft that’s press-fit into the idler door. They may be filled with particulate from years of printing and might be shot. Or maybe they need to be cleaned (soaked in 91% or better IPA) and lubed with a light synthetic oil, and will carry on for more years.
Either way, you’ll have to try to remove the idler door and try to press the shaft out of the printed door part without breaking anything. This may be easier said than done so if you have a way to print a spare part just in case, that might be wise.
Attached are a couple pics from the MK3S+ assembly manual for reference. Go to help.prusa3d.com and look for the manual for your specific printer. You might want to order a new set of gears, shaft, and bearings as a backup, and maybe a replacement idler door if needed.
Best of luck. Let us know how you make out.
RE: MK3 filament not extruding
Looks like that was the problem! I followed your instructions with the removal, soaking, and lubing and the gear spins again. I'm printing and so far no problems! Thanks for the help.
RE: MK3 filament not extruding
Excellent! Glad to hear it was an easy fix!
Enjoy!
R-