The UN threadform designator was selected as the first two letters of the word UNified. The Unified threadform was developed jointly by the governments of Canada, Great Britain, and the U S A to be an INTERNATIONAL standard that would overcome the logistical problems encountered during World War II created by the non-interchangeability of the U S and British standard threadforms.
Interestingly, ten years after the Unified threadform was introduced, its basic geometry of the Unified threadform was adopted by the International Standards Organation (ISO) as the ISO Metric threadform. Naturally, the Diameters and Pitches of the ISO Metric threads are dimensioned in millimeters rather than inches.
Some decades later, the ISO accepted the Unified threadform as an ISO Standard threadform, under the name ISO Inch.
It's true that many textbooks and other supposedly-reliable references say that the anti-acronym of the UN threadform designation is Unified National, but the originators of the threadform were specific that their intent was replace national-standard threadforms with one Unified international threadform.
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Today's Featured Article - Grain Threshing in the Early 40's - by Jerry D. Coleman. How many of you can sit there and say that you have plowed with a mule? Well I would say not many, but maybe a few. This story is about the day my Grandfather Brown (true name) decided along with my parents to purchase a new Ford tractor. It wasn't really new except to us. The year was about 1967 and my father found a good used Ford 601 tractor to use on the farm instead of "Bob", our old mule. Now my grandfather had had this mule since the mid 40's and he was getting some age on him. S
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