WTS: True metric threads are 60 degree just like US threads. There have been a number of different British thread standards used over the years, including Whitworth. There was a standard for cycle threads and one that is frequently used on models, British Association (BA) which is actually a metric thread.
Miller is correct that the US threads are technically flat on the top and bottom, but in my experience most are lathe cut with sharp Vees to eliminate the need to grind a special tool for each TPI to be cut..
Last edited by Tom Martin; 12/17/16 03:41 PM.
