Coen said:
Haha, this is the most ridiculous metric-bashing I've read so far [laughing]
...
LOL, it was actually meant as explanation .. there was a
non-commercial incentive to
not use English units which were the de-facto "world standard" thanks to their industrial prowess in 19th century. At that time, "inch" was actually
different everywhere in the world as it was a not a global standard.
In this environment, given the Germans wanted/needed to export, their natural choice was not to use the *English* imperial inch which had political connotations for their customers (the French) but to use something else (German inch being obsoleted by SI agreement by then) which was the then-new SI system.
Ref, "Germans were conquered by the French so adopted SI stuff", you sure know it was actually the other way round. Couple years before the 1875 SI conference the French got a thorough beating from the Prussians in the 1871 war ... that war was quite important BTW, as it was the catalyst for the unification of Germany into the German Empire.
My main point was that there was needed an -external- , non-commercial, factor to allow the (I believe better) SI system to win and, in turn, to create the conditions for the intermediate collet size to become prevalent. And even that took the better part of a century to take place.
Were it left for the market, most likely the most-prevalent "English inch", later "metric/standard inch" would have likely stayed put and there would be no equivalent of the 8 mm collets on the market as it is not in the US.
The sheer momentum of the consumer and small-business markets mean that a game-changing characteristic or a strong external incentive is required to challenge a prevalent standard of the time. Being just "better" is not enough. What is "better" anyway ...
As the 6+8+12 mm "system" is not *that* better to a 1/4"+1/2" system to make that happen, I do not see that happening any time soon if ever. 8 mm is likely to get better availability, given the prevalence of online shipping these days which have less inventory restrictions, but that is about it.