HotRodPaint:I am like you I spent many years working in the Tool & Die Industry.Normally when you saw a two place decimal (.02) you could hold that tolerance easy,usually + or - .010.When you saw a three place(.002) decimal it was usually + or - .005 which required a little thought.When you saw a four place decimal (.0002) it was usually + or -.0001 and you were usually grinding to hold that tolerance in a controlled environment with calibrated measuring instruments. I know greater tolerances are attainable but they never came my way.