Makerbot #453 : Hard to print Small parts

I have so many problem when i'm trying to print small parts. :-(
I had to print a square of 12 X 17 X 2 mm with a design cuts inside. That make a 2 mm between the side and the hole. Gush, it was not a big success. I printed something better with a 1.5X bigger version.
Need to put time on Calibration :-(