Workhorse TPU SL toolhead

I’m having a lot of trouble printing large objects (a phone case) using SainSmart TPU and the SL toolhead. At some point in the print in the print I’ll get what looks like under-extrusion. I’ve gotten as far as about 1.5 layers, but it frequently happens in the first layer. I’ve attached a picture.

I’m using the Lulzbot Cura slicer, most recent version, and I’ve updated the firmware.

I started with the “Standard” NinjaFlex profile and adjusted that. I’ve tried a wide variety of temperatures, I’ve changed all the speeds to 10mm/s, I’ve tried a number of different tensions on the idler, different flow rates from 100% up to 145%, retraction is off, I’ve dried the filament, etc, but I always run in to the same issue.

I have been able to print small things with no issues.

Has anybody had success printing larger objects with TPU on the 0.25mm nozzle? If so, what is your trick? :slight_smile:

Thanks for your help!