Spools not turning smoothly in AMS HT

Bambu Lab AMS AMS HT
1

I have four AMS HT units, and all of them create some resistance when the spool turns. No matter what I do, I can’t print TPU 95A HF from any of them.
I’ve tried a direct path with the PTFE tubes straight to the machine, but nothing seems to solve the issue — the spool simply doesn’t turn freely enough. When I use the external spool holder, everything works flawlessly, but not with the AMS HT.

Do you have any suggestions for this?
I’m only using Bambu Lab spools, original PTFE tubes, and all genuine parts.

It does manage to produce some prints, but there are clear signs of abnormal under-extrusion, to the point where it just webs the filament ultra-thin onto the plate.

2 Likes
2

The bypass tube was slightly too long. I pushed it out a bit, and now everything seems to be working as it should. I had used the recommended length inside the AMS HT, but in reality, only about 5 mm of PTFE should be protruding inside.