Do you mean the tolerances for the wire gauges? if so then you need to measure them to at least three (or five) times better than the tolerances of the thing you're measuring. (it's important that the wires are exactly the same size - i.e. to within 0.00002")

As to the thread diameter tolerances for a given fit, is this of any help (they list A & B fit)?

http://mdmetric.com/tech/thddat7.htm


Quote Originally Posted by GeoffS View Post
Hello from the US. I have been machining for the last 12 years, mostly CNC, and have run into a problem that I'm hoping someone in the UK can help with. I am cutting a 1/2 G parallel pipe thread in titanium. I have found all sorts of info on the thread (od, pitch diameter, minor diameter) and have run the calculations in the machinist handbook to find best wire size and measurement over wires (.040). Could anyone tell me what the tolerances are for diameters?

Thanks,

GeoffS