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The 39th Root of 92

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Re: The 39th Root of 92

#51

Post by rm445 »

einhverfr wrote: post #28
ysleepy wrote: post #3

I continue to be baffled by the arcane units in the US. This uses a measure on the completely wrong abstraction level. An accidental production process now defines a wire unit instead the end result the consumer/engineer/technician wants to know (mm^2 or inch^2 oh no no it's pica^2 ?). There must be some sociological phenomenon going on that keeps the US from adopting modern units. Maybe can't admit a shortcoming and…

I am not sure. American units usually focus on divisibility and factoring of integers, while metric units focus on quick base-10 math. So they are different concerns and this is why, I think, people from elsewhere in the world have so much trouble understanding American units. If you are brought up with metric units, the units are built around the number system. A good way to understand the problem by for the HN audi…

Shout out to another base-12 fan. If only we had 12 fingers it might have happened.

Arbitrary divisions of angle aren't very interesting, since the radian is so fundamental. But there is an angle system using multiples of 100: gradians. 100 is a quarter-turn and the internal angles of a triangle add up to 200. A lot of electronic calculators still offer them (the DRG button = degrees, radians, gradians).

Re: The 39th Root of 92

#52

Post by rm445 »

toomanybeersies wrote: post #36
MikeTLive wrote: post #8

Earlier quoted context omitted.

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…

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.

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.

Re: The 39th Root of 92

#53

Post by stdbrouw »

kevhito wrote: post #18
ysleepy wrote: post #3

I continue to be baffled by the arcane units in the US. This uses a measure on the completely wrong abstraction level. An accidental production process now defines a wire unit instead the end result the consumer/engineer/technician wants to know (mm^2 or inch^2 oh no no it's pica^2 ?). There must be some sociological phenomenon going on that keeps the US from adopting modern units. Maybe can't admit a shortcoming and…

If you have never wired a house for electrical, then sure, the units seem arbitrary. But if you do, then the units seem very comfortable. 12ga for most typical 20a circuits, 14ga for light, 10ga or thicker for some heavy-duty circuits. Hey boss, we seem to be all out of 3.31mm^2 romex, all I got left is 2.08mm^2. And why did you mention cross-sectional area? Why not radius? or diameter? Or better yet, circumference?…

Same deal for metric, though. I know I need 0.75mm2 for small appliances, 1.5mm2 is your run-of-the-mill cable for up to 10A (equal to 20A at 110V), 2.5mm2 and 4.5mm2 for heavy-duty circuits.

I've sometimes heard the same remark about temperatures: jeez, how do you guys manage to work with something as unintuitive as degrees celcius? But really, you just get used to whatever it is you're using.

Re: The 39th Root of 92

#54

Post by hengheng »

einhverfr wrote: post #28
ysleepy wrote: post #3

I continue to be baffled by the arcane units in the US. This uses a measure on the completely wrong abstraction level. An accidental production process now defines a wire unit instead the end result the consumer/engineer/technician wants to know (mm^2 or inch^2 oh no no it's pica^2 ?). There must be some sociological phenomenon going on that keeps the US from adopting modern units. Maybe can't admit a shortcoming and…

I am not sure. American units usually focus on divisibility and factoring of integers, while metric units focus on quick base-10 math. So they are different concerns and this is why, I think, people from elsewhere in the world have so much trouble understanding American units. If you are brought up with metric units, the units are built around the number system. A good way to understand the problem by for the HN audi…

> American units usually focus on divisibility and factoring of integers

The other day, right next to the problematic awg definition, I discovered the kcmil. Which is a kilo pi/4 Micro square inch.

Re: The 39th Root of 92

#55

Post by hengheng »

einhverfr wrote: post #28
ysleepy wrote: post #3

I continue to be baffled by the arcane units in the US. This uses a measure on the completely wrong abstraction level. An accidental production process now defines a wire unit instead the end result the consumer/engineer/technician wants to know (mm^2 or inch^2 oh no no it's pica^2 ?). There must be some sociological phenomenon going on that keeps the US from adopting modern units. Maybe can't admit a shortcoming and…

I am not sure. American units usually focus on divisibility and factoring of integers, while metric units focus on quick base-10 math. So they are different concerns and this is why, I think, people from elsewhere in the world have so much trouble understanding American units. If you are brought up with metric units, the units are built around the number system. A good way to understand the problem by for the HN audi…

> American units usually focus on divisibility and factoring of integers

The other day, right next to the problematic awg definition, I discovered the kcmil. Which is a kilo pi/4 Micro square inch.

Re: The 39th Root of 92

#56

Post by e2e8 »

Turing_Machine wrote: post #43
e2e8 wrote: post #38

Earlier quoted context omitted.

awg14 or whatever isn't exactly the perfect gauge for whatever application it is used for. It is somewhat arbitrary. A nice metric system of gauges would have 2 mm, 2.5 mm, 3 mm, etc. and there would be still be a nice round number gauge for each application.

For some value of "nice round number". What really matters with most wires is the current carrying capacity, which largely depends on the cross-sectional area , not the diameter. Equally-spaced diameters don't give you equally-spaced areas.

Sure. Those number I gave could be areas. I am not certain this the right standard, but IEC 60228 specifies 0.5 mm2, 0.75 mm2, 1 mm2, 1.5 mm2, 2.5 mm2, 4 mm2 etc...

https://en.wikipedia.org/wiki/IEC_60228

Re: The 39th Root of 92

#58

Post by rm445 »

engi_nerd wrote: post #33
jonahx wrote: post #16

Earlier quoted context omitted.

> There must be some sociological phenomenon going on that keeps the US from adopting modern units. Maybe can't admit a shortcoming and fix it? There's a sociological phenomenon at play here all right... a deeply pathological form of envy that Freud called "denial of USA-number-one-ness."

Okay, I'll play devil's advocate here. There's a huge (but not insurmountable) lock-in effect behind wire gauges. All the wire I can buy is sized in it. All the wire strippers, crimpers, pins, sockets, plugs, jacks, terminal strips, insert/removal tools and clamps I can buy are sized around the AWG standards. Bulkhead passages in ships and aircraft are sized for carrying certain numbers of wires of certain gauges in…

Yes, that's the core of the issue. The US is a big monobloc, an economic superpower with not only the most advanced economy but also a lot of the history tied to developing the world's industries.

Other places saw more benefit to adopting SI units either because they were smaller and closer to lots of other places with a need to harmonise, or playing catch-up. My own country, Britain, falls in the first group - though the population still uses some everyday old units, it didn't manage to be a hold-out despite its historic position and industrial heritage.

It's hard to see the position being static in the longer term though, particularly if world economic growth gradually leaves the USA with a relatively smaller slice (in absolute terms much bigger, but a smaller proportion) of the larger future world economy.

Re: The 39th Root of 92

#59

Post by e2e8 »

jacobolus wrote: post #47
Turing_Machine wrote: post #43

Earlier quoted context omitted.

For some value of "nice round number". What really matters with most wires is the current carrying capacity, which largely depends on the cross-sectional area , not the diameter. Equally-spaced diameters don't give you equally-spaced areas.

If you have an industrial production process which is going to produce a set number of wire sizes, and you want them to be maximally useful for a wide variety of applications, you want a logarithmic scale. Responding to commenter e2e8: Using 2mm, 3mm, etc. would be substantially less functional. Once you have a log scale, it hardly matters whether you measure diameter or area, that’s just a constant factor. In the id…

You can plot out the wire gauges you want on a log scale and then round them to nice whole (metric measurement) numbers. That is in fact what is done for things like fasteners.

Re: The 39th Root of 92

#60

Post by int_19h »

kevhito wrote: post #18
ysleepy wrote: post #3

I continue to be baffled by the arcane units in the US. This uses a measure on the completely wrong abstraction level. An accidental production process now defines a wire unit instead the end result the consumer/engineer/technician wants to know (mm^2 or inch^2 oh no no it's pica^2 ?). There must be some sociological phenomenon going on that keeps the US from adopting modern units. Maybe can't admit a shortcoming and…

If you have never wired a house for electrical, then sure, the units seem arbitrary. But if you do, then the units seem very comfortable. 12ga for most typical 20a circuits, 14ga for light, 10ga or thicker for some heavy-duty circuits. Hey boss, we seem to be all out of 3.31mm^2 romex, all I got left is 2.08mm^2. And why did you mention cross-sectional area? Why not radius? or diameter? Or better yet, circumference?…

The "it's more natural" argument, fielded by both sides, is largely a myth - take it from someone who lived in several countries and struggled with different units. Pretty much the only reason why something feels natural to you is because that's what you are accustomed to using.

There's nothing more natural about an inch than a centimeter, and nice, round, easy-to-remember numbers can be had on both scales for "natural", commonly found distances. Ditto for pounds and kilograms, Celsius and Fahrenheit, acre and hectare etc.

Objectively, metric wins because it uses the same decimal scale as our number system, and because the units are designed to establish the most straightforward relations between different quantities.

Yes, using 12 for a base has some advantages due to more divisors, but not being consistent with decimal wipes them all out (and traditional units don't consistently use 12, either - consider units of volume, for example). In an ideal world, we'd have 6 fingers on each hand, and use base-12 everywhere; alas...

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