Im trying to print Bambu TPU 90A using X1C + AMS HT (Generic TPU profile, with various tweaks)
Followed guide by redirecting filament through TPU exit with a straightish run into the back of the printer (no hub)
I’m using Generic TPU profile, which on various attempts tweaked temperature.
It won’t feed. If I create slack at the reel side and manually extrude, it feeds. This is further backed up by the calibration print lines where the first line has melted filament , but the subsequent are patchy, then no filament.
Make sure the PTFE inside the printer is in good shape, no internal wear, no sharp bends, and is fully inserted into the printer. There has to be no resistance at all for it to feed correctly.
Thanks, I checked the pipe and moved the AMS HT to where it was virtually a straight run. I just think the reel is too heavy for the stretchy material but it appears to work for some people so just dont understand what’s going on.
I don’t understand why the AM HT does rotate to help the situation.
Feeding TPUs from external spools is always tricky, but there are a ton of posts here and elsewhere showing how others have made it work.
AMS units work with the AMS buffer and feed based on pressure - when there is “more” filament than is needed, that makes the buffer slider move, and it sends a signal to the AMS to stop feeding until the pressure reduces. With flexible filaments, that is difficult because the filament just buckles rather than resists - since TPU isn’t fed through the buffer, there is no signal present to tell it when to feed, so that’s why the rollers can’t help.
Bambu released a TPU assist recently that solves all this, it acts as a feed motor to help push TPU along. I have it and it works well.
Although the main reason was general drying of filaments, one aspect of buying an AMS HT was for TPU; i didn’t realise it was this problematic but ill keep trying if it is possible. I just dont want to bother wasting time if some aspect of my setup adds resistance and thus it will never work without lots of modification that I dont have time for.
RE AMS and pressure… Ahhh I see, hence the spring (IIRC). Its a shame the TPU buffer wasnt included on the back of the HT but maybe it came after.