Reminds me of a young machinist in our R&D shop in the nuc biz way back. He was barely old enough to shave. Big, quiet, polite kid. He had felt tip pen marked up a batch of parts with "NFG". The leadman came unglued when he saw how nearly the whole batch of parts had "NFG" on them. He said; "...how the (explitive) could you mess up that many parts before you stopped???" The kid had a puzzled look. Then he said; "Those marked ones are not finish ground. I still laugh about that over 30 yrs later.