I’ve been trying to print some things in TPU, using a fairly soft 85A TPU, and I keep having under extrusion.
I’ve already reduced speeds to max 25mm/s, and reduced retraction. My printer uses a direct drive extruder, and as far as I can tell, it’s grabbing the filament just fine. I’m printing at 240°C, using my default 0.4mm volcano CHT brass nozzle.
zero retraction, dry the filament out (If It’s not a short-notice print, I’ll dry it out in a food dehydrator the night before, timing it so it comes out just as I’m starting the print.). Slow it down. Slow it down some more.
If the under extrusion is constant, try checking the filament’s diameter on the roll, if that’s fine, try upping the flow just a bit. TPU is fairly squishy and stretchy at the same time, so it may need tweaking. Also, consider running a temperature calibration tower.
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zero retraction, dry the filament out (If It’s not a short-notice print, I’ll dry it out in a food dehydrator the night before, timing it so it comes out just as I’m starting the print.). Slow it down. Slow it down some more.
If the under extrusion is constant, try checking the filament’s diameter on the roll, if that’s fine, try upping the flow just a bit. TPU is fairly squishy and stretchy at the same time, so it may need tweaking. Also, consider running a temperature calibration tower.