WilleeCue said:Can you really see .001" difference in index with the naked eye?
Maybe. Lets say you were cutting grooves in a ring billet. If you got to the last one and were .001" off, your eyes would not compare a "correct" gap to a gap that was off. Your eyes would be comparing the gaps on each side of the wrongly indexed groove. One gap would be .001 smaller than the correct ones, and the other gap would be .001 larger than the correct ones, making those two gaps .002 different. You might be able to see a .002 difference.
Kelly