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Filament only prints for a limited time  

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skatun
(@skatun)
Active Member
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.

 

 

Posted : 07/10/2022 12:35 pm
Diem
 Diem
(@diem)
Famed Member

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,

Posted : 07/10/2022 4:03 pm
skatun
(@skatun)
Active Member
Topic starter answered:
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. 

Posted : 10/10/2022 10:16 am
skatun
(@skatun)
Active Member
Topic starter answered:
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. 

Posted : 10/10/2022 7:14 pm
skatun
(@skatun)
Active Member
Topic starter answered:
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.

Posted : 10/10/2022 8:18 pm
skatun
(@skatun)
Active Member
Topic starter answered:
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. 

Posted : 11/10/2022 8:52 pm
skatun
(@skatun)
Active Member
Topic starter answered:
RE: Filament only prints for a limited time

Posted : 11/10/2022 8:58 pm
JoanTabb
(@joantabb)
Moderator
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

Posted : 11/10/2022 10:30 pm
Diem
 Diem
(@diem)
Famed Member

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,

Posted : 12/10/2022 12:00 am
skatun
(@skatun)
Active Member
Topic starter answered:
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

 

 

 

 

Posted : 13/10/2022 11:40 am
skatun
(@skatun)
Active Member
Topic starter answered:
RE: Filament only prints for a limited time

Posted : 13/10/2022 11:40 am
Diem
 Diem
(@diem)
Famed Member

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,

Posted : 13/10/2022 6:27 pm
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