What I find amazing is that one thousandth of an inch is not particularly precise when it comes to machining. You can easily make parts to that accuracy with common mills and lathes.
Also surprisingly (to me) is if you have a pin that goes into a hole that is 1-2 thousandths of an inch larger than the pin, it feels like a sloppy loose fit. If you want the pin to feel like a really nice smooth fit you need more like a couple TEN THOUSANDTHS of an inch clearance.
Also surprisingly (to me) is if you have a pin that goes into a hole that is 1-2 thousandths of an inch larger than the pin, it feels like a sloppy loose fit. If you want the pin to feel like a really nice smooth fit you need more like a couple TEN THOUSANDTHS of an inch clearance.