Only 1 of 4 MK3S printers stringing, just started recently
 
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SuperheroDIY
(@superherodiy)
Active Member
Only 1 of 4 MK3S printers stringing, just started recently

Hey everyone, 

I hate to even have to post this issue, but I'm just confused at this point and am looking for suggestions. I have a total of four (4) Prusa MK3S machines, and all work extremely well. However, one of them (the oldest) has started stringing for some reason and I cannot figure out why. 

To be clear, I print the same things on all four machines - same gcode, same filament, everything. However, this machine is the only one that has started to allow stringing - and a good amount of it. It's mostly angel hair and easy enough to remove or blast with the heat gun, but problematic when you are filling the bed with prints. 

I thought maybe it was a worn nozzle, so replaced that with a brand new E3D 0.4mm nozzle, and same issue. I thought maybe the hotend thermistor was damaged, but it looks good. I've certainly tried the same roll of filament and same print on the adjacent printer and the other printer doesn't string at all!

The weirdest part is this just started out of the blue with no changes. Any ideas what could cause this? Worn extruder gear maybe?

Posted : 17/06/2021 2:18 am
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Only 1 of 4 MK3S printers stringing, just started recently

Assuming that the complete mechanics are ok, I would reduce the nozzle temperature a little, increase the speed of the front fan slightly, adjust retraction and print speed. The printers are all the same type, but differ slightly from each other due to manufacturing tolerances.

wbr,

Karl

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen....
Posted : 17/06/2021 9:55 am
towlerg
(@towlerg)
Noble Member
RE: Only 1 of 4 MK3S printers stringing, just started recently

Environmental issues, drafts etc.?

Posted : 17/06/2021 11:16 am
Swiss_Cheese
(@swiss_cheese)
Prominent Member
RE: Only 1 of 4 MK3S printers stringing, just started recently

@superherodiy

 

I would check the idler tension and make sure the Bondtech gears screws are tight (the ones folks refer to as Grub Screws). all normal maintenance steps, you sound like you know what your  doing but its possible to miss things when doing tune-ups or after cleaning.

 

Good Luck

 

Swiss_Cheese

The Filament Whisperer...
Posted : 17/06/2021 6:37 pm
bobstro
(@bobstro)
Illustrious Member
RE: Only 1 of 4 MK3S printers stringing, just started recently

Any chance you did an extruder e-step calibration on the odd one? If you saved values that adjusted the extrusion rate, it might account for that. You can always do a factory reset and run through the calibration steps if unsure. 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 17/06/2021 6:54 pm
Swiss_Cheese
(@swiss_cheese)
Prominent Member
RE: Only 1 of 4 MK3S printers stringing, just started recently

@superherodiy

 

were you able to resolve your stringing issue? if so, how?

 

Regards

 

Swiss_Cheese

The Filament Whisperer...
Posted : 21/06/2021 7:19 pm
SuperheroDIY
(@superherodiy)
Active Member
Topic starter answered:
RE: Only 1 of 4 MK3S printers stringing, just started recently
Posted by: @swiss_cheese

@superherodiy

 

I would check the idler tension and make sure the Bondtech gears screws are tight (the ones folks refer to as Grub Screws). all normal maintenance steps, you sound like you know what your  doing but its possible to miss things when doing tune-ups or after cleaning.

 

Good Luck

 

Swiss_Cheese

Thanks for the reply. I definitely thought it could be a maintenance issue, but I've been over everything outside of taking apart the extruder assembly. The strange thing is that everything else is perfect, just retraction is still off. 

Posted : 25/06/2021 2:26 am
SuperheroDIY
(@superherodiy)
Active Member
Topic starter answered:
RE: Only 1 of 4 MK3S printers stringing, just started recently
Posted by: @bobstro

Any chance you did an extruder e-step calibration on the odd one? If you saved values that adjusted the extrusion rate, it might account for that. You can always do a factory reset and run through the calibration steps if unsure. 

Now this is an interesting thought, and not something that I've looked at again but might be worthwhile! I think I'll do a factory reset and make sure to re-do the PID tuning and e-step calibration and see how it turns out. Thanks for the suggestion!

Posted : 25/06/2021 2:27 am
SuperheroDIY
(@superherodiy)
Active Member
Topic starter answered:
RE: Only 1 of 4 MK3S printers stringing, just started recently

Looks like the e-steps were perfectly calibrated ... so unfortunately that's not it. 

Posted : 25/06/2021 3:57 am
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