Sunlu TPU entangled around Bowden  

Sunlu TPU entangled around Bowden

Hi everyone.. after a couple of almost successful  prints on my MK3S with SUNLU TPU (even if with a nozzle temp of 190°C, lower than the producer recommends - 205 to 230), I collected a number of failures with a new print

I already disabled retraction at all, and reduced the speed to 20 mm/s, but in any case, after a number of successful layers (let's say 10-12 mm high) , the print starts the become irregular (as if the filament struggles being extruded), then the flow stops, even if the printer continues to move as if it is normally printing..

I aborted the print, then I tried to remove the filament, but it is blocked: disassembling a bit the extruder assy, I found the TPU filament entangled around the Bowden: it seems that the Bowden itself tries to push fhe filament, but the "drag" from the extruder is too high, and so the flexibility of the filament makes it turning around the shaft of the Bowden.. or at least this is what I think is happening

I also repeated the print with a slightly different GCODE, and also by reducing a bit the tension on the Bowden driven gear.. no luck!

suggestions?

thanks

Rosanna