Thats machinist talk for tenths of a thousands of an inch. And thats because that is what my old Sunnen dial bore guage reads in. In other words just enough to true her a skosh
Yup. "It's off three tenths." = you missed it by 0.0003"
"Take half a thou off" = remove 0.0005" of material.
You missed it by ten thou. NOT "one hundredth". = 0.010"
"You missed it by a c^nt hair" = I can make it fit with a hammer. I used to have a CH taped on a 3x5 card in the top of my toolbox. "NBS Certified CH - 0.0032"
NFG or FUBAR = Do not use. Good for scrap.
Strange thing about machinists. If you are good, you never miss anything by .001". You miss it by .025 (jig bore), .100, or .200". Why? This is how much you screw up if you count the handle turns wrong.