Please forgive me if this has been bashed out before, but I've been thinking again (Oh NO! they cried).
For years I've wondered about the series of angles of the MT tapers. I thought the wierd spread of angles might have derived from some esoteric mathematical formula beyond my ken.
Acting on the clue that they were originally based on a taper of 5/8" per foot (19.2 : 1) and with the help of Excel and dredging up some rusty trig functions, this results in taper angle of 1° 29' 26.630"
Since the MTs all hover round this figure, was it decided by the Wise Men (& Ladies?) that because of its, by then, widespread adoption, to stay with the errors and eventually carry them forward for the ISO standards? Pehaps only the improvements in measuring instruments and machining processes since Steve Morse nutted it all out in the mid 1800s only later allowed the small but significant errors to be observed in the standard prototypes?
BTW, my calculated angle rounded off is the given taper for MT0, which leads me to wonder whether MT0 was one of the original series, or (from the "0" designation) was it added post-Mr.Morse with the grteater accuracy then available?
Or is there a "proper" reason for the series?
In the meantime, I'll continue to machine my MTs by setting up against known store-bought tapers.