[MikeTLive]

Appelbaum: So the people blocking adoption of the metric system weren't backward-looking traditionalists, but cutting-edge industrialists?

Mihm: That's correct. While the anti-metric forces included outright cranks, including people who believed that the inch was a God-given unit of measurement, the most sophisticated and powerful opponents of the metric system were anything but cranks. They were engineers who built the industrial infrastructure of the United States. And their concerns, while self-interested, were not entirely off base. Whatever the drawbacks of the English units, the inch was divided in ways that made sense to the mechanics and machinists of the era: it was built around "2s" rather than "10s," with each inch subdivided in half and in half again—and so forth. This permitted various sizes of screw thread to have some logical correspondence to all the other increments. The same was true of the sizes of other small parts that were essential modern machinery.

http://www.theatlantic.com/technology/archive/2015/06/whos-a...

[rz2k]

The philosophy seems to be reversed with the ISO 216 paper size standards like A4.

Anyway, the main advantage of metric seems to be its universality between different markets, rather than the somewhat silly idea of ideal relationships such as water in one arbitrary form having a certain weight and volume replacing a system that was derived from a hundreds of years process resembling a genetic algorithm.

[einhverfr]

I wonder if it is an internal/external optimization. The whole point of metric is that it is built around the number system, leading to easy conversion between units.

The whole point of the American unit system is that they are optimized for specific use, but definitely not for conversion.

ISO paper sizes are a great counterexample, actually, because they took an application, rather than a conversion-centric approach. I.e when you print a signature you do so on a larger piece of paper, and then you fold, crop, and bind. Each fold cuts the paper size in half.

So ISO paper sizes are much more like American units than American paper sizes are.

[toomanybeersies]

So where to 3/8" and 5/16" threads play into this? They aren't easily divided by 2, or multiplied by 2 to make a larger thread.

[ArkyBeagle]

3/8 is half between 1/4 and 1/2. 5/16 is half between 4/8 ( 1/2 ) and 3/8.

[rm445]

5/16" is the world's most compatible thread. The numbers are close enough that, in the most common thread pitch, you can usually get away with using it interchangeably with M8.

[ysleepy]

Yeah the engineers love the process of calculating if that wire can carry the specified current. Because it's so industry friendly.

This is complete nonsense and sounds like musings of a desperate advocate.

If you want to believe something, you start to accept the lamest arguments.

[HCIdivision17]

You don't really recalculate that stuff over and over, do you? Every electrician I've worked with has a couple of the main ratings memorized and just applies it to standard. Anything more complex requires a calculator or tables either way, and once you're not doing the math in your head, it really doesn't matter what units you use. They're all arbitrary, so you may as well snap 'em to an integer value of convenience.

You'd certainly also want a universal one for conversion, but not for every day tedium. Fahrenheit is nice because it spans the human experience in a nice range (say damn cold 0 to rather hot 100). But that's bunk if you're in context of chemistry where water's properties are far more comparative (0 freezes to 100 boiling). Though absolute scales are always a bit sporky, since they latch to a scale and wonk it sideways (-273 is a silly number no matter what anyone says).

And so on. Scales and units are merely benchmarks. Literally. Pick the right bench for the job and follow the marks.

(Though with enough effort you can make any scale work. Kinda like hammers and threaded carpenter nails.)

Edited; typing on phones ruins grammar.

[jolhoeft]

I actually did this a lot when I was designing electric motors. One detail the original article didn't note, is the 39th root of 92 is very close to the 6th root of 2, off by half a percent. This makes scaling for voltage changes simple. Going from US 120V to European 240V? Go up three wire gauges and double the number of turn.

In practice, it was not quite that simple, because of the half percent error, and wire insulation doesn't follow the same scaling pattern, but it was still quite handy, and much less trouble than metric, where you constantly had to dig out the wire gauge chart.