Dr. Luigi: It is very typical in the Open_SCAD source I play with to see where people have put fudge factors into the source code. For things like precision meshing gears, there are almost always some fudge factor numbers that get added to one thing (like how big the spaces are) and subtracted from other things (like how thick and deep the teeth are). The thing that made me just give up and drill to get precise holes is the fact a lot of these pieces of source code I was looking at were super well written and very clean. If the author needed a fudge factor to make the code work, what makes me think I'm going to get away without one?