OK, I had troubles with a bunch of other holes as well, took my calipers to my parts and bolts, and get 4.98mm holes and 4.82mm bolts. So I modified the STL’s that need threads, using the method I normally do (inscribed polygons). This usually gives perfect threads without tapping in ABS, but sometimes needs tapping for PLA/PETG (anything more than M3 anyways). In case I’m not the only one, I posted the files here for others to use.
zenxy-v2-truck1A-threads.zip (882.9 KB)
zenxy-v2-truck1B-threads.zip (795.7 KB)
zenxy-v2-truck2A-threads.zip (880.9 KB)
zenxy-v2-truck2B-threads.zip (783.1 KB)
zenxy-v2-zenCenter-threads.zip (1.0 MB)
I was conservative and did not hexify both sides of holes that did not need it. This should make assembly easier. I took care to thread the top halfs on those deep counterbored bolts, which allows you to back the bolt out all the way easily (had to drill a hole in my stock center part to get a bolt out of it).
I wondered why this was never an issue with the MPCNC, then realized looking at it that it doesn’t have any tapped holes (all backed with nuts). I know some recent upgrades to my printer have resulted in better looking prints… looks like that upgrade also gave very accurate dimensions to my crusty old A8 (5mm holes used to be 4.9ish).