xyz calibration (not automatic)
I tried printing a 10x10x10mm cube https://www.thingiverse.com/thing:4579476 and measured some slight differences.
This is the calibration done by the wizard. I'm wondering if there is a way to adjust the firmware tuning, to get it dialed in even closer.
I would print a larger calibration cube, let things like extrusion width and volume become less significant. 20mm or even 40mm for a good dimensional accuracy test.
Some time ago I printed three 20mm cal cubes as a sanity check, with PLA, ABS and PETg, all at .10mm layer size. All three came well within 1% when measured with a digital caliper and any of the I3 series should be able to do this.