85A TPU has gaps mid print

[spiral hearth]

Sunlu 95a TPU in polydryer@22%RH
Printing on P1S 50% speed
I'm using this profile and it's been working great for the first few layers then the break sets in.
Tried different flow rates, temp range and speeds. It's always breaking before the middle of the print, but at different heights, so I doubt it's hardware or layer time/feature related.
If I had to guess, it would be tension/friction related. My setup is having the spool sit in the polydryer dry box, not actively drying while printing and feeds through the back of the printer. I've seen people having success with similar setup and the prints are showing me that the extruder isn't losing grip or have reduced flow rate but I'm wondering if it's delayed that much into the print? And if so, would it be better off feeding it directly from the box to the extruder with the top glass opened?

[rustic island]

Yeah typically tension, but maybe you can get results with a slightly slower speed?

[vale hearth]

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[spiral hearth]

I'll try again with even lower speeds. Thanks

[spiral hearth]

The cube was on 30mm/s, 0.6mm retraction. It's happening with the benchy at 25mm/s at 0.4mm retraction. So I'm guessing it's just retraction and speed?

This is the setup btw

[spiral hearth]

I'm guessing retraction because afaik most layer adhesion problems, especially with flexible materials, stems from retraction, speed or temp. Temp is well within range at 230C and speed should be ok. Plus, retraction has a lot to do with friction/tension in filament

[rustic island]

ok, can you test something please?
just undo the ptfe tube from above the tool head + hotend, and give the filament a gentle tug. this should give you an idea of how much resistance is on it.

when you say 20mm/s, what setting are you referring to? retraction speed?

[vale hearth]

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[spiral hearth]

Sure.
It's the layer speeds

It's now at 10mm/s and 15mm/s for later speeds. The rest is at 15-20

I think it's the cooling

[spiral hearth]

The side towards the aux fan peels much easier than the side away from it

Second pic: has signs of wanting to peel of but then I manually turned it off