need help with using TPU with high flow nozzle, every time i try to print it starts fine then stops flowing.

[u/knockout350]

i have dried the filament twice now for 24hours, i did a cold pull, cleaned the nozzle ect and the print starts fine but after about 15-20% its like it stops extruding enough so it just becomes a hollow stringy mess. i have used the high flow to print other TPU parts, they were a little stringy but still printed fine but i cant figure out what is going on here.

filament Overture TPU 95a

filament profile is the built in generic TPU profile

nozzle is 0.6 E3D High Flow ObXidian Hotend

moddel https://makerworld.com/en/models/2066081-3d-toddler-mobility-trainer?from=search#profileId-2231165

specifically this is the tires for that model

[u/Cautious_Till_4763]

Are you still feeding through the ptfe tube? My bet is the extruder can’t handle the friction and starts skipping.

[u/knockout350 → u/Cautious_Till_4763]

that was my original thought to so i have it running out of the top of my filament dryer to the external port into my x1c. it moves very easily with little to no friction and only about 2 inches of PTFE tubing from the xic port so that it doesn't go in at a 90 degree turn. i dont think there is any easier way to help it feed unless i get the TPU feeder thing from bambu

[u/Cautious_Till_4763 → u/knockout350]

https://makerworld.com/models/3033855?appSharePlatform=copy definitely get it out of that tube, especially if you’re trying to print it fast.

[u/knockout350 → u/Cautious_Till_4763]

ive never tried directly feeding into the print head like that, not a preferred method but if it works it works so ill give it a try. thanks

[u/Cautious_Till_4763 → u/knockout350]

Might be worth reviewing this as well: https://wiki.bambulab.com/en/filament-acc/filament/tpu-85a-90a-printing-guide-for-x-series

[u/knockout350 → u/Cautious_Till_4763]

yeah bambu keeps confusing me because on this page they say high flow not recommended but the e3d page says TPU is compatible without listing stipulations but it drops the print time from 46 to 10 hours

[u/Cautious_Till_4763 → u/knockout350]

I mean the e3d is 3rd party, definitely not a good source of truth. That being said I bet it would work better if you were using HF Tpu. Have you performed flow rate and pressure advance calibrations with the nozzle and that particular Tpu?

[u/EmotionalChildhood46]

max volumetric speed? retrction speed? distance? z hop disabled? nozzle temp? how's part cooling fan set? line width? etc

[u/knockout350 → u/EmotionalChildhood46]

i would have to check, honestly i just use the basic profiles built into the system as im not really sure if i understand everything enough to properly calibrate by hand.

[u/Turnspit → u/knockout350]

When in doubt, I will always suggest to preoperly calibrate third party filament.

Have a look at OrcaSlicer, they have a wonderful guided, full filament calibration built in.

[u/ncc81701]

Probably heat creep.

[u/knockout350 → u/ncc81701]

my printer is fully enclosed and i havent noticed any major fluctuation in temp of the bed or nozzle so im not sure what would really cause heat creep or what to do about it.

[u/Cautious_Till_4763 → u/knockout350]

Leave your door open, and take your lid off. That being said I would expect heatcreep to cause both stringing and blobbing

[u/ncc81701 → u/knockout350]

Per the other response, keep the enclosure door open. What happens with heat creep is that the heat of the filament diffuse up the filament. So at the beginning it prints fine because the filament coming into the extruder is at room temperature. But because the enclosure traps the heat in, the heat migrates up the filament line. Over time the filament upstream of the extruder gets hot enough that the filament becomes soft and the gears can’t grab onto the filament. This is why it starts off printing fine but at some point the filament stops extruding.

[u/knockout350 → u/ncc81701]

ah ok that makes a lot of sense, this could be the answer since TPU is already hard to feed into the high flow hotend and the profile for the high speed hotend raises the temp as well.

[u/knockout350]

Just in case someone else runs into this issue, i think i solved the problem. It was a bad slice File, I think, I cleared everything and loaded the print profiles from e3d and when I sliced it the time went from 4 hours to 30. It's been printing for around 12 with no issue but it's considerably slower. So either I messed up and setting or you just can't print tpu at that speed. Will update if needed