First time printing with TPU. Another problem I had was that it didn’t stick to the textured print bed, had to go for smooth PEI which I read (and now can confirm) is not ideal. Would satin be better?
That’s inconsistent extrusion.
As others have mentioned, the first thing I’d look at is thoroughly drying the filament. TPU is very hygroscopic and will become nearly unprintable within a couple of days of coming out of the dryer.
Beyond that, you may be trying to run it faster than your hotend can melt it. TPU is pretty resistant to melt and cranking temp doesn’t help a whole lot. Actual flow can vary pretty wildly between brands depending on their exact blend but I’ve seen TPUs that refuse to flow more than around 2mm³/s through a standard 0.4 nozzle. (Volumetric flow is roughly layer height * width * linear speed).
Tpu is the worst with moisture. Even new rolls need drying.
Not necessarily. If you don’t hear any sizzle like little pops when extruding you are fine.
Also watch out for retraction amount and speed. You don’t want more than 1 or 2 mm of retraction at 15mm/s and try to only print that slow as well.
That looks like a moisture issue to me. Some TPU filaments will absorb so much water from the air that when heated, the water boils out and creates awful bubbling and pitting in the printed part.
TPU is tricky. Did you tune All The Things for it, separate things PLU settings? Off the top of my head I use 230 nozzle, 40 bed temperature (instead of ~200/60) and the retraction settings are different. I think the base speed had to be tuned too. Even then, my prints don’t turn out as smooth as id prefer. The balance of walls and infill numbers can be a dance.
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