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 - Restoration Story: Fordson Major - by Anthony West. George bought his Fordson Major from a an implement sale about 18 years ago for £200.00 (UK). There is no known history regarding its origins or what service it had done, but the following work was undertaken alone to bring it up to show standard. From the engine number, it was found that this Major was produced late 1946. It was almost complete but had various parts that would definitely need replacing.
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