mk3s (+mmu2) stops print mid filament / what temperature should a hotend-surface have?

mk3s (+mmu2) stops print mid filament / what temperature should a hotend-surface have?  

Active Member

Hi, I have the same problem as many other described here, that my (PLA) prints stop mid-print after a while. So far I did some changes, which did not cure the problem.

  • changed the nozzle (still 0.4mm brass)
  • installed a silicone sock (now temperature doesnt drop anymore when the cooler starts. That helped to get into the 2nd layer)
  • increased temperature by ~10°C (that helped a bit, in particular together with the silicone sock)
  • installed an additional fan on the extruder motor (that stepper motor is now cool)

Most prints fail with the clicking noice, but sometimes also without it. There is always no plastic extruded or serious under extrusion visible 🙁 It happens with different filaments (all PLA). Following the temperature on octoprint, I see no irregularities (+/- 1°C) on the nozzle or the bed. Prints are 0.2-0.3mm layer height. And I have disassembled and cleaned the bondtech-gear on a regular basis.

I also removed the case I built (especially when printing PLA), but that doesn't really solve the problem. Air-temperature is around 20-25°C max.

So on my quest to get a working printer, I am now looking at the temperature, particular of the hotend. I used and IR thermometer for that. The bed is easy to measure, and within 1-4°C of the printer value. The hotend is a bit harder to measure, but measuring the around the nozzle and covering the whole sensor with the heat-block , I got a maximum of 165° (215°C on printer) and 200° for ABS settings (255°C on printer). Can anyone measure their hotend and tell me what temperatures they get?

On the positive side:

  • I had hundreds of hours of successful prints before, including mmu2s. 
  • when the print doesn't fail, its good/flawless.
  • PETG prints succeed - however I don't print them so often.

Any help is appreciated.

Posted : 11/09/2019 2:14 pm
Dave Avery
Honorable Member

I would expect the temp to be close the what's indicated. it almost suggests the thermistor may be failing

Posted : 11/09/2019 7:17 pm
Active Member

Btw, I am happy back printing and could solve issues by switching from Eryone-PLA to "" Obviously all changes made before are still in place (extruder cooler, silicone sock...) and I enjoy them, but all "print stuck mid-filament" have magically disappeared. 

@david: i printed 2 temperature-towers afterwards to check, but so no temperature irregularities as one would expect.
However, the print failed anyways - and did not fail with another brand.

..and I am happily printing with enclosure again (doors open with PLA). 

good luck to everyone

Posted : 17/09/2019 2:09 pm

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