It is a communicative convention. If you're the only person following a convention, it isn't.
At least this is an additive one - unlike imperial/metric, it isn't a unit replacement. Even if you like "better" measures, you may want to stick with local ones. Little story -
I noodle around with metalwork, and have some machinery. Because I lived in Europe for a bit, I am comfortable with metric, and metric mental math is so much less error prone that when I was choosing machinery, I went metric. That was a mistake.
Everyone I've had in my shop freaks out. All the little rules of thumb and patterns for remembering relations between, say, feed rate to mill spindle speed for a particular alloy go out the window. Reading documentation and how-to texts written in the US puts you right back at doing lots of math in weird bases in your head. And so on.
It is fine, I'm happy with my setup. But there are reasons not to pick the "better" method. And those reasons perpetuate the existence of the other ones.
It might be a mistake in the US, but of course machine shops outside the US are all metric - conversely, operating an imperial machine shop might be quite annoying outside the US.
> It is fine, I'm happy with my setup. But there are reasons not to pick the "better" method. And those reasons perpetuate the existence of the other ones.
Interestingly the US industry didn't switch to metric citing "conversion cost" (in the late 19th / early 20th century). Instead we continue to waste billions every year since: keeping double stock, projects failing (see: space), US engineers struggling with the system everyone else uses (and vice versa, though to a lesser extent, since US-made components and machinery are relatively irrelevant in industry) etc.
I live in Canada, we use metric, I had to learn imperial when I started at a machine shop. The machines all worked to .0001 inches and we measured our pieces to 1/16" accuracy. Personally, despite using metric all my life and using it for almost everything else i've done. Using imperial and fractions of inches for that kind of work was more intuitive for me and a lot easier to figure out in my head. I find it a lot easier to mentally add fractions than decimals.
> Using imperial and fractions of inches for that kind of work was more intuitive for me and a lot easier to figure out in my head. I find it a lot easier to mentally add fractions than decimals.
Imperial fractions also tend to use base-2 numbers as the denominator. I'd be willing to bet that you infrequently saw anything that used thirds or fifths. Most everything would have been halves, quarters, eighths, sixteenths or even thirtyseconds of something.
> Interestingly the US industry didn't switch to metric citing "conversion cost"
This isn't in the past - it is an ongoing argument that literally anyone who spends any degree of time in a machine shop gets roped in to. Every machine purchase is a vote on the ongoing argument.
Which is why I explicitly called it out - because of a collective action problem in the US, we can't make a simple, obvious efficiency change (which would indeed cause comparatively brief pain for large ongoing payoffs)[1]. It was a mistake for me to switch for the reasons specified. The interesting part is that correct micro-scale choices create a macro-scale problem.
Seems to be an ongoing theme of the past couple of decades.
[1] If you're not familiar with this, curious why a simple standards issue is well and truly unsolvable, and feeling masochistic you can search Youtube to catch what passes for mainstream political talking heads here making it about "heritage" and how the metric system is part of a UN plot.
The worst thing is (ignoring the irony of sticking to 'imperial' measures, as in old British empire measures), US imperial measures are different to imperial measures elsewhere.
At least with the metric system there's no ambiguity, and it's base10 so easier to calculate, and the orders of magnitude make sense. And they also translate; a litre of water is functionally equivalent to a kilogram in weight.
At least this is an additive one - unlike imperial/metric, it isn't a unit replacement. Even if you like "better" measures, you may want to stick with local ones. Little story -
I noodle around with metalwork, and have some machinery. Because I lived in Europe for a bit, I am comfortable with metric, and metric mental math is so much less error prone that when I was choosing machinery, I went metric. That was a mistake.
Everyone I've had in my shop freaks out. All the little rules of thumb and patterns for remembering relations between, say, feed rate to mill spindle speed for a particular alloy go out the window. Reading documentation and how-to texts written in the US puts you right back at doing lots of math in weird bases in your head. And so on.
It is fine, I'm happy with my setup. But there are reasons not to pick the "better" method. And those reasons perpetuate the existence of the other ones.