Thank you. It is not a design flaw because I printed a part with 6.40mm hole in it. When I measured the part with a caliper it is 6.32mm.
The outside diameter of the part turned out to be 47.95mm but in the design it is 48.35. I can compensate by adjusting the scale over x and y in the printing profile?

Are there any new 3D printer slicing STC to G code programs in developement?
Slicr is very user unfriendly (as most open-source software is) while Makerware is not open source.