Even with the door and top lid open, when the printer has been working for a while, when printing TPU I get a clog caused by heat creep (lower part of the filament, 3-4 cm or so, when finally extracted, is noticeably thicker).
If I’ve been printing ABS I have to wait around 2 hours until I can print TPU.
Any ideas of how to solve this? (I’ve tryed turning on chamber fan, lowering bed temperature…)
Make sure the hotend fan is operational. It’s there to cool down the heatbreak to help prevent heat creep.
Have you tried lowering the hotend temperature? Your filament is apparently more heat sensitive, which also means you should probably be using a lower setting for printing it.
Depending on the surrounding environment and ambient air temperature, it can take longer to bring temperatures down. But I would say 10/15 minutes would be already excessive. Considering heat transfer physics, to spend two hours bringing down the chamber and extruder temperatures to near ambient temperatures, either your sensors and fans are faulty, or your printer is in an environment that offers significant thermal resistance (within an insulated chamber), or your ambient and surrounding temperatures are close to the ones in the printer (this seems highly unlike).
Hotend fan is always on, working as intended. Lowering temp helps, but layer adhesion is worst… I’m thinking of upgrading to the Mako Slice Engineering hotend to try to fix this…
I’ve seen some colors (same brand and material) are more sensitive. Green is always perfect, as black. But blue is a PITA
I’m not sure the Mako will be a solution. It’s just another heatbreak, with the stock fan.
The “bimetallic” is nothing new, nothing to write home about anyway. They were offering this for other hotends awhile ago. I tried one and on a Neptune 3 Pro it was worth it. On a Bambu I doubt it. The heatsink is just aluminum too.
I will bet you’ve dried it. I bring that up because I had the same issue with Sirya Tech HF tpu. It would clog so quick it was aggravating. Using a Revo then, tried everthing. Contacted them and they asked to dry it, after I put it in the dryer for a day. Once I left in for quite awhile it printed very well. BTW, used stock settings for the revo on tpu. I’ve since run the stock hotend, E3D hotends with the same results. Something to think about.
These are the profiles for the Mako. You could look them over.
I think Mako could help because that bimetallic heatbreak should stop heat bleed upwards, but maybe you are right and the gains are negligible.
Yes, I tryed drying it and results are similar. It might take a bit longer to clog, but it ends up clogging. So maybe I have to leave that filament for winter only… 
In summertime it gets worse, but hardware is not faulty, and I don’t live in a hot place. So I guess it has to be this material, that might be too sensitive to heatcreep…
Just assumed it was BL TPU-HF, is that right. Won’t change anything really. Just wondering.