@mrehorstdmd Fascinating. Appreciate the feedback. That makes me curious about whether I should try some different models to see if it's consistent across them. If the single-wall extrusion case is the only deviation, I think I'd live with it.
Is it safe to say you've tried both single-wall (non-vase) and regular parts, and 85% works well for both?
I also haven't played with how extrusion rate might affect it. So far in my testing, I've stuck with a tortoise-like 2.4mm^3/s just to limit whatever nonsense may crop up at higher flow.
So far I've tried rolling backwards to 2.04 firmware, and the behavior is the same there. Currently running a print on 2.02b firmware to see if it's still there.
If it's the same there, I think I'll try pursuing your thought of verifying it's consistent across the 'normal model' scenarios, and maybe just live with that. I'm quite happy with the machines output without pressure advance, it's just that 'chasing tenths' mentality, knowing that round pieces come out slightly more round than oval, and the seams are marginally less visible that has me irritated. That and just the stubborn desire to understand and conquer the problem haha.
