I use Cura for a few weeks and I just realized that my parts are 80% of the desired size on the X and Y axes ... The problem is I think I have pulleys with 16 teeth at instead of one with 20 teeth. Solution: change your step / mm by 100
I calibrated everything a few months ago with Repetier which memory of this famous problem of 80%.
On Cura he reappears? It may also be because I have an external control module introduced at the same time as Cura.
I was via Arduino change the line in the firmware Marlin and I uploaded to the map