Just realized I spent 3 days chasing a taper error that was one loose setscrew
Last Tuesday my X axis started drifting about 0.008 on every finish pass and I spent three days re-leveling the machine, checking backlash, and re-cutting my master, all in my shop outside Akron. Turned out one setscrew on the old ballscrew coupler had backed off just enough to slip under load, and a quarter turn with an Allen key fixed what three days of head scratching couldn't. Anybody else got a story where the fix was dumber than the problem?