I'm getting really bad stringing on every print, to the point where it's pretty much unusable. This is my first time printing with TPU, so I'm at a loss for what to do.
Direct Drive mod - After modding the printer I did a few prints with PLA, and it works great with very little stringing. So I assume I assembled the mod correctly and that's not the issue.
Material - Reviews of the Overture TPU on Amazon mostly say it has low stringing and are generally positive, so I'm assuming it's not just bad filament.
Temperature - The consensus in the Amazon reviews seems to be that 230°C is the sweet spot. I did a temperature tower from 205 °C to 230 °C by 5 °C, and the print quality and stringing was pretty much uniform throughout.
Retraction - I tried with retraction off, then with 1 mm, 2 mm, and 6.5 mm, in various combinations with temperature and speed. Results varied in details, but all were pretty bad.
Speed - I tried slowing down to 15 mm/s (from Cura's default of 50). Results got even worse.
Following are photos of a stringing test with various combinations of settings.
Is there something else I should try to reduce stringing? Is it possible that I just got a bad spool of TPU? Or is it more likely something's wrong with my printer?