Filament only prints for a limited time
So after 1300hrs on my MK3s, i started to get problems when printing, it started dripping droplets of filament once in a while which made it skip steps, stringing issues etc. I had nozzle change at 800hrs and my first guess was that the new nozzle was bad. New nozzle did not help so got new temperature sensor, and lowered the temperature based on test tower print. Still same issue. I then took the whole extruder apart and I found that it leaked filament between the heatsink and the heatblock, however the heatblock and heatsink(on threads) was so full of plastic so I ordered just a complete new one. Then it was back to recalibrating first layer, got all that done. Then started the print, was fine for first 3 layers, then it just stopped protruding filament. I took the extruder appart again, changed the the PTFE tube to a new one, recalibrated the spring on the idler.
Downloaded a bed leveling test file from prusa, it prints the outer perimeter string nicely, then it stops extruding filament. I got a filament dryer box now, same issue that its stops extruding filament after a short amount of time. What can be the issue? I feel like I have changed most of the extruder now except of the steppermotor gears. Loading and unloading of filaments works fine.
Is this an instant stop as if the extruder was switched off or a gradual fizzling out?
A picture of failed print might help.
When changing nozzles pay particular attention to the diagrams at the bottom of this page:
https://help.prusa3d.com/en/article/changing-or-replacing-the-nozzle-mk2-5s-mk3s-mk3s_2069
But be aware that not all nozzles, especially some of the cheap clones, are compatible with the i3, some are about a millimetre too short.
Cheerio,
RE: Filament only prints for a limited time
Thanks for the reply, I noticed one thing, that the idler spring seems unreliable. So trying to fix that now. I also adjusted front and rear bed level to -20 because it seems like it was to high in the middle. Sometimes it seems that the extruder skips steps. I started a 7h print now, will see how it goes and post some pictures.
RE: Filament only prints for a limited time
here is a picture
https://photos.app.goo.gl/GJbqRkwaauBfy4aJ7
Today its stopped printing after 1hour, then I restarted the same print job after retighten the bed screws. It then ran for almost 4 hours. I noticed that the top right screw for the extruder motor affects the idler lid, so it might be an issue there. I will lubricate the spring tomorrow and loosen the extruder motor screw. I also noticed that the head of the idler screw changes position with and without filament.
RE: Filament only prints for a limited time
Quick night update,
So I found a few errors,
- the PTFE tube were kinda loose, i.e when retracting it could move up a little bit, I never double checked the new hotend, so my mistake!
- Misaligment of filament and gear by 0.2-0.4mm , probably something changed slightly when reassmbling the extruder
- Sanded a little bit on the idler bracket so now it runs a bit smoother
Will reprint tomorrow and post an update.
RE: Filament only prints for a limited time
So I have printed for roughly 14 hours since last update, and it starts skipping steps around 4-5hours in. Print quality is superb untill then. I can then do a unload filament. cut of some filament with clearly thread marks on it and reload filament and it print just fine for another 4-5 hours. However I have noticed that when doing unload filament i have to pull really hard on the filament even if I unscrew the idler screw.
RE: Filament only prints for a limited time
RE: Filament only prints for a limited time
have you changed your extruder fan (Left hand fan?) having the wrong fan can cause problems like this. (there is a hidden experimental menu, that allows you to boost the Fan Speed for non standard fans).
Have you tried reducing the retractions to say 0.4mm?
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Your first layer Z calibration is a little low and I notice there are fingerprints on your print sheet. None of these will help.
Please how us a picture of your hotend/nozzle assembly from at least two different angles.
Cheerio,
RE: Filament only prints for a limited time
Have you tried reducing the retractions to say 0.4mm?
its at 0.8 now, and 0.4mm z movement, Is there a G-code sample file which can run retraction back and forth to see if thats the issue? But I agree with you that the retraction might be the issue and hence it happens only after a while after several retractions after each other
have you changed your extruder fan (Left hand fan?)
No, its the original,spinning fine
RE: Filament only prints for a limited time
Your extruder fan has collected a lot of dust which must reduce efficiency, clean it with a stiff paintbrush and a blast of air.
Raise the extruder and show us a picture of your hotend/nozzle assembly from at least two different angles, I want to see where excess plastic is going.
Cheerio,
RE: Filament only prints for a limited time
So I can finally confirm that it prints nicely again with both PLA and PETG. So the issue I think was:
After I changed the nozzle it did not screw all the way in, maybe it was 0.1mm or so from the heatsink for some reason. So it started to leak slowly between the heatsink and the heatblock and coming out on the top side of the heatsink and then dripping filament down on the print bed.
The extruder was in such a bad shape I were not able to clean it properly, and it had mpre than 1000hours on it, so I just got a new one of ebay for like 30USD with heating element and temperature sensor. This one was crap! As you guys mentioned the nozzle that came with it was bad as well as the heatsink would not go all the way in, leaving to little room between the nozzle and heatblock- also the ptfe tube did have a lot of backlash. So I ordered a new one without cables and with lock ring for PTFE tube. Some minor adjustment to the lock ring to make it fit inside the extruder bracket and now everything works just perfect!