Exact same stl file - a 20mm solid infill PLA cube with no surface features.
When sliced with cura it is accurate to 0.01mm but has some quality issues.
When sliced with S3D it is about 0.2mm too big but looks perfect (due to variations in the order of printing walls/infill etc).
The extrusion multiplier is set to 100 as is the flow setting. The printer's E e-steps have been calibrated.
What else could be causing this?
tyvm