In an old question I just self-answered, I had ongoing problems with corner curling that went away due to my switching to using Cura's Outer Before Inner Walls (
outer_inset_first) setting. Now, since there are sometimes reasons to prefer not to use that setting, I'm trying to figure out how it makes the difference.
My initial hypothesis was that the inner walls are pressed outward slightly beyond their nominal position, due to skin and infill overlap settings, and that when there's not sufficient room for the outer wall material, the path of least tension at a corner is for it to curl upward (whereas along straight edges it's just remaining in a straight line). However, disabling infill and skin overlap did not significantly improve things. Could it just be slight remaining bulge at the corner of the inner walls? I'm using Marlin with Linear Advance calibrated to avoid that, and visually there doesn't seem to be such a bulge, but it at least seems vaguely plausible.
What are some other plausible explanations to invesigate?