why is the US not Metric

[KL27x]

bsfeechannel:

Since when you give a damn what the Canadians do?

I thought you did? Take a guess who said these things:

...They don't know how to use metric exclusively. And this shows that they don't know everything about metric.

...This doesn't justify the US, because metrication there is not on par with the rest of the world, that uses metric for just about everything.

...The rest of the world IS 100% metric and you know that's true.

...Nope. You need to make it exclusive, and deprecate the old cumbersome system for the general public.

Canada, UK, Netherlands and other EU countries using pounds in daily lingo: Am I a joke to you?
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Nope. I started out in this thread questioning your argument that the US is not metricated because it costs money. Well, no one said that the change would be free. My argument back then was that the whole world managed to go metric and paid for it. No problem.

So you didn't say any of these things?

...The cost of switching to metric is in fact marginal. And the benefits enormous. If that weren't true, the world wouldn't have taken the plunge.

...Can't you see the forest for the trees? Just extrapolate to the whole country the benefits these companies had from investing in the use of metric instead of imperial and that's it.

...It is intuitive. [how many $billions you will save!]

...The whole economy profits from the reduction of the amount of redundant units to measure the same thing.

...The same straw man again? Can we proclaim you Your Majesty, the King Of The Straw Men? Of course it is not about me and my screws. The screws are an indication of a FACT: imperial costs more to maintain. And that's the point.

...The whole economy profits from the reduction of the amount of redundant units to measure the same thing.

Repeating a claim doesn't make it true.
So what do you back this with?:

...You might have missed this text from a link I posted six pages ago.

For example, total metric conversion costs for the 50 state highway departments are estimated to lie between $50 and $100 million. The states spend about $20 billion on highway construction every year so a 1 percent reduction in construction costs due to improved productivity and quality amounts to an annual savings of $200 million. At the 1 percent rate, the payoff for highway conversion takes 3 to 6 months with a savings of 100 to $150 million the first year and $200 million each succeeding year. Even at a tenth of this rate, the payback period is only 30 to 60 months with savings in each following year amounting to $20 million in perpetuity.

LOL. I'm ok with the rest of the metric world enjoying all of these savings. Maybe you should keep this a secret so your metric brothers can continue to reap these benefits for themselves. Then you can band together to "kill the imperial zombies," who are a relic of the past.
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If my arguments are wrong, childish and simplistic, how do I always manage to question yours?

You don't. You dismiss them or ignore them completely and then yell "Then why did everyone else change to metric!? Straw man! Imperial is dead! Just look at all the memes on the internet!"   

I refer you back to your own post #1027, on the previous page 42. You ask a question as if it hasn't been answered already. And then despite taking the time to reply, once again, you twist it. I explain yet again, and then you conveniently forget you asked in the first place. Back to your same old. When you get pwned, just spout more crap until it is covered and hopefully forgotten.

[blacksheeplogic]

Why either of these these? Bring back the Sumerians Sexagesimal system.

[vwestlife]

And this argument has been equally debunked ad nauseam in this thread. The US "gone metric where it makes sense" only defeats the purpose of metrication, which is to reduce the clutter and confusion of units.

That's like saying Canada has "clutter and confusion" of languages because they are a bilingual country.

[KL27x]

Not to mention he denies even that "3)  The US is metricated where it makes sense." Even after he provides the list of the major export businesses which all changed. In the 60's and 70's and 80's.

8 )  Metrication can only occur under a general cultural and political upheaval.

not only, but mostly.

Starting with France, revolution.
Russia-cum-USSR (basically this includes east europe): 8 years after the Bolshevik revolution.
Germany: Napolean. 
Poland: nuff said.
China: during Beiyang under martial law
Japan: Meiji revolution

This is 10 minutes of research, and it already over half the globe. (and at least 50-60 million people killed)

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Completely metric, ya right:

South Korea: read about this yourself. South Koreans sound a lot like Americans, other than the government going apeshit and using propaganda and fines for over 60 years and counting, and still losing that battle. These dudes still using old units by stating them in metric. In America, this is like real estate agents' use of square feet being punished by fines, so the people call them square ~1/3 meters *wink wink* while flipping the government the bird.

North Korea: No one know how complete or easy/hard, but they just use their old units but rounded off in metric. Like the dutch use pounds as 0.5kg.

Japan required 50 years to get mostly metricated. (And this did not stop them from using metric where it mattered). Interestingly, US units were also recognized as legal in Japan around the 1900's, when they had 3 officially recognized systems (US, metric, and traditional). Also fun bit, Japans traditional units are based ten.

Iran and Turkey still use many persian units (which go back to 500 BC, and which the weights and volumes were related by water)

Again, this is just a few minutes of reading. And I tire. This just goes on and on and on.

bsfeechannel, maybe you can learn something between now and your next post.

[ebastler]

8 )  Metrication can only occur under a general cultural and political upheaval.

...
Germany: Napolean. 
...

I don't think so. With some goodwill, you can consider 1834 as the starting point for metrication in Germany. (German customs union introducing the metric pound, which is exactly half a kg.) Things got seriously metric in the 1870s.

Napoleon didn't have much to do with that, I think. He would have had a hard time, given that he was dead since 1821, and powerless since 1815. I didn't check your other history claims, but the result of this one spotcheck makes me wonder...

Edit: Looked into one more. Poland seems to have gone metric in the 1870s as well. What terrible events in that period were you alluding to with your "'nuff said" comment?

[vwestlife]

Anybody else remember these? Rulers marked in tenths of an inch, as a stepping stone to Metrication by decimalizing inches. They also tried to make the Metric equivalent easier to remember by rounding it off to "1 inch = 25 mm". (Hey, the Bible says Pi is 3.0, so isn't that close enough?)

[KL27x]

Thanks, ebastler. We can x that off the list, i guess. Major reforms of their systems started in the Napoleonic era. As per Napoleans own preference for France (and what the N Koreans do), they did this by defining and rounding their units to metric. But you can give Germany credit for the "full" metrication in 1870, using the actual metric unit names.

By this standard, is NK metricated, yet?

Also, Portugal is said to have been the first country after France to adopt metric, in 1814. But this was limited in success, and they didn't let go of their native unit names until 1856. Fun fact, A canada was a unit of volume which was close to a liter, pre-1814. And equal to a liter from 1814-1856.   

[ebastler]

Anybody else remember these? Rulers marked in tenths of an inch, as a stepping stone to Metrication by decimalizing inches.

That concept seems to have stuck in electronics, somehow. 

Come to think of it, I had not even realized that all standard "inch" scale tape measures divide the inch into binary fractions!
Which is a brilliant concept, and leads to this:

https://www.youtube.com/results?search_query=how+to+read+a+tape+measure

Easily a hundred "How to read a tape measure" videos on Youtube!
And every single one of them refers to the imperial-scale version...
Wonder why? 

[Zero999]

Worse, as I showed earlier, the tools and/or industry standards can't always deal with these different prefixes. So you will use what you have. If your scale or caliper only displays in certain units, then that's what you choose from. Sometimes grams might be better. Sometimes grains. Sometimes milligrams. Depends what you are doing. No matter what you know in your head, the way you work will be affected by your available options when it comes to tools and standards.

Given all this, why are you so gungho about eradicating options other than metric?

Because having more standards is counterproductive and confusing. The more unambiguously something can be defined, the better. Fair enough, in informal situations it might suffice to say a handful, a hair's breath, a thumbnail etc. but when documenting something, it's better to use the same units, even if it may occasionally result in smaller or larger numbers, than one would normally deal with. Fortunately the SI system deals with large or small numbers with simple prefixes, to make reading and adding up much easier.

Notice how we have standard values for component values? We could have a lot more, but it makes life easier and components cheaper, as fewer values need to be made.
https://en.wikipedia.org/wiki/E_series_of_preferred_numbers

"Milliturns" might be sliced bread for specific things. Grads might be great for certain things. But is it worth changing how airplanes navigate in order to switch to milligrees of lattitude and longitude? Is it worth retraining your artillery crew with new dope charts for distance and elevation and wind?* Changing geometry and scientific calculators to use 1000 milligrees for sin and cosine and tangent? To make a right angle 250? Do you have to "choose the best" and then use only one single system for every single function we perform using measurements? You will fix a lot of stuff that isn't broken; and you will introduce new problems just by sheer coincidence of seemingly innocuous differences that manifest in funny ways in specific applications, particularly where humans apply prior knowledge and experience and training. IOW, if the French artillery is hitting what they're supposed to, maybe let them keep using grads.

You've missed the point. Angles are all fractions of a circle. The argument for using powers of 10 isn't so relevant, as they are for measurements of physical quantities.

For example, if I gave someone a drawing, all the linear dimensions in mm and angles in degrees and asked them to scale it by a factor of 5, the angles will all remain the same. It wouldn't matter whether the angles were specified in, radians, gradians or milliturns, they would remain the same, as long as the x, y and z axis were all scaled by the same factor. Scaling the same drawing specified in feet and inches would be more tricky, for the reasons discussed previously in this thread, but it wouldn't affect the angles.

[KL27x]

scale it by a factor of 5

Can't you scale dimensions in any unit, though? Can you elaborate?

Angles are all fractions of a circle... The more unambiguously something can be defined, the better.

So... having and using both grads and degrees makes it more or less clear/ambiguous?

Really, as long as you keep your usage focused for the task, you can use either in whatever the situation requires. French military might use degrees for navigation, but grads for artillery, for instance. But your whole post isn't making a lot of sense to me.

Fair enough, in informal situations it might suffice to say a handful, a hair's breath, a thumbnail etc.

This is a pet peeve of mine. This is straight from the hive mind of english speaking europeans and college numbnuts. This is not how we use imperial in America. We use imperial for the highest levels of precision manufacturing/machining, just as much as borrowing "a cup of sugar" from the neighbor. Fractions, OTOH, are often used like this. E.g. quarter pound of pastrami. The fraction, itself, kinda denotes an acceptable toerlance, that as long as it rounds to 2/8ths it is close enough. Vs 125 grams of pastrami. Also the size of the unit can convey that, as well. Requesting 4 oz of pastrami would imply a tighter tolerance than 1/4 lb; it would be like asking 4/16th lb of pastrami.

When measuring stuff to sort into sizes, say a pile of sticks that isn't all uniform, you might round to nearest half cm, for instance. Or you might in imperial use quarter inches or half inches or eight inches, depending on how tight you want to sort them into multiple sizes. For grading or for the next process. So if you use an inch measure once a year, it might be confusing. If you use it for a repetitive task, it might be more useful/versatile, once you hone in on what you're using it for. 

[SilverSolder]

When you say "high precision" in terms of US customary units, normally "mils" (1/1000 inch) spring to mind.   E.g. think of hole spacing on a PCB.

[KL27x]

Personally, I love this unit for precision work. It's small as I need so far, in half a century of life. One mil makes a difference. Within 1 mil, it doesn't matter; I'm done with my job in PCB work. In machining, any further is called sanding/finishing/fitting. But since backlash from the international internet, I have been trying to call them thous, rather than the "mils" I learned from Eagle. Apparently, there's 0.0001% of the metric universe that calls millimeters "mils," and lots more will confuse mils to mean millimeters, even they never use either irl. "Ton" I also vow to concede to metric, thanks to conversation with v6kzgo in this thread. (I want to use kips, instead).

Thous is still fine, and apparently more-used in machining. Still a lot easier to say/think than tens of mics or a hundredth of a mm.

They're trying to take all the good names! This is maybe one reason USC irks the international community?

[SilverSolder]

^Thous/mils also have the benefit of being a decimal measurement, just like the Metric system.  It is a kind of half way house between the two systems, to my mind.

And a thou is approx a quarter of a tenth of a mm!  :-)

[schmitt trigger]

19) After 1000+ posts, this thread is not closer to resolution, than it was on post 2.

20) This thread will become one of the Top-3 longest threads, ever. Might even debunk TEA for the first place within this decade.

[bsfeechannel]

19) After 1000+ posts, this thread is not closer to resolution, than it was on post 2.

This is not the kind of thread that comes to a resolution. What we can do is expose the false claims and debunk them. One by one.

20) This thread will become one of the Top-3 longest threads, ever. Might even debunk TEA for the first place within this decade.

Well, I learned a lot with this thread. I came to respect much more the painstaking work done along those many decades by the brilliant minds that established metric as the dominant system around the world. I also came to understand that imperial is not a mere inconvenience. It is an obstacle and those who are working everyday to have it disappear deserve our praise.

[bsfeechannel]

not only, but mostly.

Starting with France, revolution.
Russia-cum-USSR (basically this includes east europe): 8 years after the Bolshevik revolution.
Germany: Napolean. 
Poland: nuff said.
China: during Beiyang under martial law
Japan: Meiji revolution

All those countries were rejecting a feudal past and moving to a new paradigm of modern, industrialized state influenced by Western scientific, technological, philosophical, political, legal, and aesthetic ideas. The same motivation behind the US's revolution of independence.

So, metrication is not the result of political and cultural upheaval. It is a consequence of the motivation to be modern.

[bsfeechannel]

And this argument has been equally debunked ad nauseam in this thread. The US "gone metric where it makes sense" only defeats the purpose of metrication, which is to reduce the clutter and confusion of units.

That's like saying Canada has "clutter and confusion" of languages because they are a bilingual country.

You could say that. However, you can't compare languages to system of units. Systems of units are objective, not subjective.

If you wake up tomorrow and suddenly realize that the speedometer in your car and the signs on the road are metric, you won't be less American than you are today. If you remove the words inches, feet or miles from every day use and now use millimeters, meters and kilometers, this won't make you less a speaker of English.

[KL27x]

The way the S. Koreans use metric to replicate their native units is the same game that America's MIC plays. The American government officially uses metric for (almost) all of their business with private companies, by that metrication law we had. Military uses metric, too. Mechanical drawings of parts are done in metric, but to standard USC dimensions, in many cases. So instead of 5" OD, the Sparrow missle body is spec'd as a 127mm OD.

This might sound like a dick move, but this means the manufacturers can stock fewer pre-formed or partly processed materials (round, tubes, bars, etc, and even perhaps further processing) to manufacture a wider array of things, including older designs still in production. It also could be that in some cases, things fit existing hardware or whatnot. This is an entire supply chain going back through various tooling down to extrusion dies which obviously can't be adjusted and to the American steel industry. The more parts you need to make, the more tooling you need to maintain, and/or to be dependent on outside sources.

Same applies to any domestic manufacturing, of course. The raw materials will be cheaper in stock imperial sizes. Waiting for these toolings to wear out and then replace with metric just means you'll be stuck maintaining both for practically ever, and complicating your supply chain between molten steel and engineering materials?

Oh, and bsfeechannel? You're not a very good reader. Not a very good PR cheerleader for your cause, either, IMO. I think I understand your POV, but your methodology of... say, promoting your views? I guess I have to pass on w/e you are smoking. I wouldn't willingly join that wavelength. But good luck on your crusade. And I apologize for being rude. Cheers.

[bsfeechannel]

Oh, and bsfeechannel? You're not a very good reader. Not a very good PR cheerleader for your cause, either, IMO. I think I understand your POV, but your methodology of... say, promoting your views? I guess I have to pass on w/e you are smoking. I wouldn't willingly join that wavelength. But good luck on your crusade. And I apologize for being rude. Cheers.

If I were promoting metric, I'd be saying something like imperial good, metric better.

[GlennSprigg]

Back on Page-42, (sorry), TimFox said...

As I understand the history, the liter was originally defined as 1000 cubic centimeters.  The gram was originally defined as the mass of one cubic centimeter of water.  The prototype kilogram was then fabricated to agree with that definition.  However, due to the temperature dependence of water’s density . . . etc . . .

Actually, although these units of mass/size/volume were limited to Water, it goes so far as to
technically specify that it was for Pure Water, at average Sea-Level, and at 21-deg C.   

On Page-43, vwestlife said...

Anybody else remember these? Rulers marked in tenths of an inch, as a stepping stone to Metrication by decimalizing inches. They also tried to make the Metric equivalent easier to remember by rounding it off to "1 inch = 25 mm". (Hey, the Bible says Pi is 3.0, so isn't that close enough?)

Sorry, but in THAT regard, there was NO rounding off!  It always was, & is, 1" = exactly 2.54cm.

And yea, here in Australia, you can still buy, (in fact the most common), tape-measures with both
metric & imperial. Comes in handy when you know/suspect something old was fabricated in imperial,
so you don't measure something as say 381mm, when it was really 15" etc. Although I would rather
add say 300mm to 450mm, then add 1' 4+15/16" to 1' 11+5/32" (unrelated comparison!)   

I don't think I ever saw 1/10ths of an inch on a ruler, (and I'm old), but of course measuring in 'Thou'
on an imperial Micrometer was common, & fairly logical. Especially when relating that on Lathe dials!
(Side-Note:  Aren't Vernier Calipers a clever invention!!  Although now electronically digital)

P.S. I used to piss off an old Carpenter at work, ordering a piece of wood from him, say...
3' 7+5/32" and 274mm. He hated it, made it right!  (He knew my humour though).   

[vk6zgo]

Back on Page-42, (sorry), TimFox said...

As I understand the history, the liter was originally defined as 1000 cubic centimeters.  The gram was originally defined as the mass of one cubic centimeter of water.  The prototype kilogram was then fabricated to agree with that definition.  However, due to the temperature dependence of water’s density . . . etc . . .

Actually, although these units of mass/size/volume were limited to Water, it goes so far as to
technically specify that it was for Pure Water, at average Sea-Level, and at 21-deg C.   

On Page-43, vwestlife said...

Anybody else remember these? Rulers marked in tenths of an inch, as a stepping stone to Metrication by decimalizing inches. They also tried to make the Metric equivalent easier to remember by rounding it off to "1 inch = 25 mm". (Hey, the Bible says Pi is 3.0, so isn't that close enough?)

Sorry, but in THAT regard, there was NO rounding off!  It always was, & is, 1" = exactly 2.54cm.

And yea, here in Australia, you can still buy, (in fact the most common), tape-measures with both
metric & imperial. Comes in handy when you know/suspect something old was fabricated in imperial,
so you don't measure something as say 381mm, when it was really 15" etc. Although I would rather
add say 300mm to 450mm, then add 1' 4+15/16" to 1' 11+5/32" (unrelated comparison!)   

I don't think I ever saw 1/10ths of an inch on a ruler, (and I'm old), but of course measuring in 'Thou'
on an imperial Micrometer was common, & fairly logical. Especially when relating that on Lathe dials!
(Side-Note:  Aren't Vernier Calipers a clever invention!!  Although now electronically digital)

P.S. I used to piss off an old Carpenter at work, ordering a piece of wood from him, say...
3' 7+5/32" and 274mm. He hated it, made it right!  (He knew my humour though).   

I'm even older, & back in the day, 1/10" divisions on the wooden school rulers was very common.
(Linear graph paper had the large divisions at 1", & the small ones at 1/10".)

The rulers  also had 1/16' & 1/32" divisions on the other edge, but they were pretty roughly printed, so the 1/10" divisions were about the limit as far as readability was concerned.
Not that it mattered much, kids don't commonly have to measure things to great degrees of precision in the classroom.
Woodworking & metalworking classes had rules with better accuracy.

[KL27x]

Although I would rather
add say 300mm to 450mm, then add 1' 4+15/16" to 1' 11+5/32" (unrelated comparison!)

I would also rather add 1' and 1.5' than 388mm and 282.9mm.  (unrelated comparison!)

Not denying that fractions aren't more work. But this is why you avoid choosing stupid numbers in the design phase. And if and when you do, you work in just inches, not feet and inches. The place where one might end up with stupider fractions is often in stackups of thicknesses, in my own experience. But even in these cases, the dimensions are often nominal or not really perfect fractions of inches (and for things like plexiglass or plywood these are usually in metric, even, so you end up with imperial + metric). If you work with hardwoods, you often need to joint/plane all what you need for X project until they're all flat... then the thickness is wherever that ends up. This is where the calipers are handy, and thous save the day and unite all measuring systems, down to the precision that actually matters - no more, no less. The most common thing you would have to precisely "measure" or "calculate" is probably (in my world) for cutting slots, and in this case you might do it with a pencil or a marking knife (no measuring at all) or calipers. Definitely not a tape measure.

From my perspective as a home/hobby shop in wood and metal working, there's a surprisingly little need to measure anything with fractions of an inch on the tape measure. Most often, it's just to make sure I have enough of w/e engineering material, to start with, and where to break it down. After that, it's more about symmetry and fit than exact numbers. The calipers/thous, squares, stop blocks, compass, marking gauges, pencils, and whatnot, are used way than 16ths of inches from a tape. No matter how close the marks, the tape is useless when it comes down to the fitting/joining, drilling holes symmetrically, et al.

[CatalinaWOW]

Yep.  You rarely use fractions less than 1/8 in rough carpentry, and even cabinet work rarely involves the smaller fractions.  Usually only doing the last fit into a wall or something like that.  The design took care of making small and uneven fractions un-necessary. 

I'm assuming metric carpenters use a millimeter as the smallest practical dimension for both rough carpentry and for cabinetry.  A centimeter is just too big for either job.  A millimeter might be a smidge big for some cabinetry work, but would suit in almost all cases.  One result of working metric is that there might not be any strongly preferred dimensions.  Perhaps even numbers.  All of this is down in the noise of work efficiency and all that.  A competent workman will handle either system well, with minor advantages in one situation or another for one of the systems.  A true craftsman who didn't have to be mobile or have space limitations might even have tools for both systems and use whichever worked best for the task at hand.  Which is more or less what I do, but my tools outrace my level of craftsmanship.  Within hands reach as I type I have rulers graduated in fractions of an inch, (and also rules graduated in a variety of divisions from 20ths of and inch and 6ths of an inch to the one I use most, tenths), metric rulers, metric calipers, US std calipers and tape measures for both.  Unfortunately I have to go a few steps to get a metric micrometer, the US STD one is in arms reach.

This ability to hop back and forth, and my tendency to work on older equipment is why I am in no hurry to switch to 100% metric.  Somebody who never intended to work on older stuff might do quite well with only metric gear. 

[KL27x]

One result of working metric is that there might not be any strongly preferred dimensions.  Perhaps even numbers.

Well, in metric home-contruction, they do have strongly preferred quantum steps. The 300 mm distance, which GlennSprigg mentioned, is a common "unit," which is a nice size (kinda like a foot) and also easily divisible by lots of factors. So when you frame a house, you can figure out the stud spacing and have two guys working on either end and be on the same page/grid. You just know different numbers to do it. Like is it 7,800 mm which is a multiple of 600? Or would it be 7,600, 8,000? The metric construction guy might know this from experience without thinking about it. The imperial worker might know the multiples of 4' or 16", better, by heart. (4' is 3x 16" stud spacing).

The architect will know the standards to best make use of materials. It's not a big deal from the design/engineering, I think. I would guess it's more the cost to change the entire manufacturing and supply chain.

We will get some different "standards," e.g. some countries use 700mL for liquor bottles, and some use 750mL. But probably not too much different from imperial. I get the feeling that metric manufacturers love increments of 25 grams/mm or 50 or whatnot, as they make smaller changes.  Rather than using things like 720 or 730. So metric loves halves and quarters and eighths, too.

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Some people think it's hilariously American that a housewife once described a Florida sink hole in the street as "big enough to swallow 10 washing machines." But compared to estimating dimensions which may require use of pi*R squared, I think these "washing machines" are actually a pretty good way to estimate/visualize the size of an irregular hole in the ground while under the gun. It's not like most people do this kind of estimation very often. If you want to figure out the mass of water it can hold, you can reverse-engineer this estimation. I'm going to guess around 15 cubic meters, give or take a top-loader vs side. I'm thinking just drop them in the hole, not change the shape of the hole to stack these things side-to-side. But if she said 15,000 liters or 500 cubic feet, would that be better for this question? I like the 10 washing machines, personally. If I ever see a sinkhole around this size, this washing machines will be my first unit of choice. 

[Zero999]

scale it by a factor of 5

Can't you scale dimensions in any unit, though? Can you elaborate?

Of course you can. It's just more difficult, than sticking with one unit. You could scale linear measurements in inches just as easily as cm, or metres and the same could be said about a recipe in oz vs grammes. The problem occurs with imperial is more than one unit is normally necessary. Any tape measure longer than 60", has both feet and inches and weighing scales, for masses over a few pounds, have both pounds and oz. In reality you'll have 6"8', rather than 80", unless you're working on something quite small, which makes life harder, than just using cm.

Angles are all fractions of a circle... The more unambiguously something can be defined, the better.

So... having and using both grads and degrees makes it more or less clear/ambiguous?

Really, as long as you keep your usage focused for the task, you can use either in whatever the situation requires. French military might use degrees for navigation, but grads for artillery, for instance. But your whole post isn't making a lot of sense to me.

My point was just use one measurement, so keep it to degrees, as it's what everyone uses and the benefits of multiples of 10 don't apply to angles.

Degrees, arcminiutes and arcseconds are pretty close to an optimum system. Angles often have to be measured very accurately, so saying 53^o 43' 15" is much easier to read than a huge decimal number of decimal places. The only time it's inconvenient is it's often necessary to convert arcminiutes and arcseconds into decimals, but just sticking to one system or the other avoids that.

We use imperial for the highest levels of precision manufacturing/machining

As did the UK and most of Europe until we realised metric was easier to use, so we migrated towards it. No one is saying, imperial can't be used for precision engineering or scientific measurements, just that it makes calculations more difficult so isn't worth the bother. It's far easier to just use the SI system which is designed from the ground up. There's no point in having 50 or so different units for length, mass, volume, area, etc. just use one. Fair enough, in some cases, it might seem awkward to have 200g, rather than 7oz, or 0.3m, or 300mm, than a foot and it makes no difference in many applications, but it doesn't change the fact that life is much easier with one unified system.