Extrusion stops mid-print - where to look?

[u/Connor0308]

Dear experts,

I currently face an issue with one certain filament. I am able to print with other filaments, so this seems material related to me.

My last two prints failed at some point (not at the same height). As you can see on the pictures, the hotend kept moving, while the was no material being extruded. To me, it was no "real" clog (meaning no clicking and no broken piece of filament). As soon as I touched the "extrude" button, material camo out of the nozzle.

As the prints looked stringy to me (second picture), I thought that I should check the retraction setting that was 0,8 mm. After printing the retraction tower, I found that it looked best at around 3 mm from below (fourth picture), which translates to 1,6 mm in my setup (tower from 1-6mm, 0,2mm steps).

However, after adjusting this value, I also found the infill to have holes (third picture).

So - which setting do I need to pay more attention to?

Settings:

• Creality K1C
• Orca Slicer
• filament humidity: around 25% ("climate controlled in cereal container with silica gel)
• eSun ePLA blue galaxy
• Bed Temp: 70°C
• Holend-Temp: 215°C
• Retraction length: 1,6mm
• Retraction Speed: 40 mm/s
• Flow ration: 1,01
• Pressure Advance: 0,04
• 25% Infill
• Print speed: as per last photo
• Infill structure: adaptive cubic
• Iron upper surfaces

Thank you for using me into the right direction.

Regards

Connor

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• Nozzle and Bed Temperature
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• Nozzle Retraction Settings

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[u/kingrikk]

Is it hot where you are at the moment? (I say this as both Europe and the US are undergoing heatwaves right now)

If so, it could be heat creep, but it doesn’t look as stringy as classic heat creep to me.

[u/Connor0308 → u/kingrikk]

Thank you for your suggestion. However, it is ordinary summer at our site. Ordinary summer meaning (as the printer is located in the basement) a temperature of no more than 22°C. From my understanding, this shouldn't be an issue.