Kilopascal wrote in USMA 20180: >Besides metric (ISO) thread sizes, I can think of Inch-coarse, Inch-fine, >NPT, NPS, and Withworth. I don't know if Withworth also comes in coarse and >fine. But, my guess is, Withworth is obsolete, except for replacement on >old machines. I'm sure Withworth has been replaced by metric. Who knows, >maybe each country had there own sizes, until ISO-metric eliminated all of >them except, of course, the American ones.
My memory from working England in 1940 was that Whitworth, British Standard Fine and Britrish Association were the common thread sizes. Joseph B.Reid 17 Glebe Road West Toronto M5P 1C8 Tel. 416 486-6071
