kasztimate

Dear all, I guess I am not the only one mentioning this issue, but i searched for many forums and sites about this problem and cant find the right solution. My problem is the following. The designed holes are getting smaller when printing. Exactly with 0.4mm no matter what is the diameter. The boundary walls of the model are perfect size. So in my case if i print out a 20x20 box with a 10mm dia hole in the middle i got the following: - outside dimensions are exactly 20x20 but the hole is 9.6mm dia. If i try to change the so called "horizontal expansion" setting with -0,4mm than i got the following results - outside dimensions are 19.2x19.2 and the hole is exactly 10mm dia. So this setting changed the desired hole size but also ruined the outside dimensions. Is it a normal thing or its kinda unique. Is there any other ways than designing it in CAD with extra dimensions like a hole with 10,4mm dia? It is weird because if im going to make some drawings for further CNC than i have to change the whole model again. I hope someone out there has the clue. Thanks in advance!