I use Simplify3D to slice my prints, and I've set it to print everything with 4000 Acceleration and 50 Acceleration for outer perimeters only.
Everything works fine, Marlin changes acceleration settings without issues, but with low accelerations my corners are bigger than they should:
The object I'm printing is this one: https://www.thingiverse.com/thing:2478785
As you can see in the model, highlighted parts in the picture should have 90° corners with perfect straight lines.
It seems that Marlin adjusts acceleration just for print speed, without adjusting it too for the extruder, so the extruder extrudes a constant amount of filament, which on slow speeds (corners) results in an overextrusion and on high speeds (lines) results in an underextrusion, causing bad corners and inaccurate prints.
This happens with acceleration between 50 and 300. If I use 1000 as acceleration for perimeters the problem is gone, but I need to use small numbers in order to have clean corners and avoid ghosting.
Am I the only one experiencing this? What could be causing the issue?