The 'missing sizes' lesson is always taught the hard way. The 'classic' DIN hex screw/nut for M10 is/was 17. (I'm not referring to extra-wide or -slim types) Then came the ISO, which was (and still is) widely ignored in Germany, where the default for M10 is still 17. But the COMECON countries (eastern europe) were quite comitted to the ISO before their breakdown. So, when a western german company ordered fasteners from local czech stock for the machinery they were going to erect in former Czechoslovakia without going into detail, they were supplied with a truckload of M10 fasteners - wrench size 16.
When our mechanics started hollering, I pulled the Friedrich (Technical reference) on them and send them off to buy tools.
You get me wrong... I'm a retired ASE-certified mechanic, with machinist/tool & die making background thanks to my grandfather. I KNOW there is no such thing as a metric size you don't need; I've known it for decades. I also know about the 32nds, 64ths and decimal metric sizes, thank you.
It's all the alleged "tool manufacturers" who've forgotten. Since EVERYTHING comes from Asia now, they seem to be the source of this idiocy.
mnem
*Kicks Horror Fraught in the nuts just on GP*
Didn't get you wrong. It was a reply on the topic, but not aimed at you.
The standards conundrum does exist on both sides of the ocean, BTW.
The hex nut sizes on UNC..threaded fasteners span mostly over three sizes, which doesn't necessarely mean adjacent ones. And in some sizes there are TWO driver sizes above the normal, because the very flat (like poti nuts) use another oversize opening than the oversize construction type. And there is a still active MIL-STD (or MS-nnnn spec) which diverges from SAE in one or two diameter/head size relations (covers some parts for E/E, could look it up).
And all of the above applies to fasteners and simple parts, as covered in the standards, only. It says NOTHING about parts being an adjustment sleeve, or a captive screw on a lid, as the designer of those can chose the actuation size that he sees fit.
The biggest oxymoron in the fastener/tool industry is the (even standardized) german/euro plain open end wrench set. It ranges from 6...22mm. Not much 6mm nuts out there, really! In the main series 6mm corresponds to M3.5, which is listed as obsolescent in most documents. And the tools that bought the tools wonder why they keep slipping on and marring the very common M3 fasteners, as they come with a hex opening of 5.5mm. Therefore the smallest wrench in the most common kits should be 5.5x7, and not 6x7! I pointed that even out to some tool company product people, which looked at each other like totally beflustered and changed the topic. Oh look, there is a polka-dotted pig dancing on the table!
I keep drivers (as blades, as square attachment, as fixed handle and wrench(es)) for 6.5 and 7.5mm routinely, for example. Also Inhex in 1mm and 3.5mm present multiply - both appear in no standard.
The downside of it is that the 'pocket toolkit' suffers the same fate as some famous 'pocketbooks'. The best example is 'Dubbel's Taschenbuch fuer den Maschinenbau', which is a sizeable hard-bound tome of 2000something pages. There is no pocket around to hold it, except the pouch of a giant marsupial maybe. The English edition calls itself 'Handbook of Mechanical Engineering', which is slightly less ridiculous.
So the topic can only be handled in one way:
Orderly! have the driver park the tooling truck next to the T&M trailer, please!
(I suggest converting a large FAUN, or, if none available, an Oshkosh P-15 for that)