EDIT2: The two problems I had were: The nozzle not being tight against the heatbreak; a hot tightening fixed this; Thinking extrusion speed and print speed are the same, grinding was occuring at 20mm/s extrusion speed which for my setup is equivalent to a 418mm/s print speed. max print speed = (max extrusion speed * pi * (radius of filament)^2) / (layer height * extrusion width) I am using an e3d titan and lite 6 in direct drive mode. I have just set them up and even though I can extrude fine when not printing it is bad when printing. I have cleaned the lite 6 out multiple times, tested with new filament, levelled the bed. I am printing at 15mm/s, 60°C on the bed and 210°C on the extruder. full resolution EDIT: seems like my lite 6 was leaking, hopefully I have fully tightened it now. But the filament is grinding now at full tension.