USA --> Metric

[vk6zgo]

It's either a Middy, Pot, Handle or a Schooner down here.

Unfortunately,there has been a "re-imperialisation by stealth",at least in WA.
Most Taverns & the like sell beer in Pints-----I think it was driven by all the little trendoids who like to pretend they are living in London!

Bunnings used to have a wide range of metric bolts,but now its a lot fewer,with most of their bolts Imperial-----I guess the Indians are still on the Imperial standard!

PS--there,that's better!--I somehow lost the "quote end" symbols!

[miguelvp]

More Ireland than London. Lot's of Irish in our melting pot.

[John Coloccia]

I guess you think it's cute to pick 50mm, instead of something like 15.7mm.  Whatever.  I don't really care if anyone else sees the usefulness of fractions in the shop.  It seems rather short sighted and close minded to me, but what else is new.  I'm just trying to explain why it's still in widespread use.  It's because it's USEFUL.

But why is it more useful than decimal, or just using multiples of 12 metric units or whatever happens to suit your project? In other words why it is better than metric?

Imperial doesn't equal fractions.  Has nothing to do with the unit of measure.

But the reason using fractions based on powers of 2 is more convenient than fractions based on powers of 10 (i.e., decimal) is that in wood working and construction you're frequently doubling and halving measurements.  You're rarely multiplying or dividing them by 10.

It's how people work in the shop.  You're constantly eyeballing and doubling things or halving things...that comes up all the time.  Even when I work in metric, I still think about things as "halfway between this and that", and rarely really care about the actual measurement.  "In the middle" is all the precision I need.  Using fractional measures based on powers of 2 means that I can very quickly note what it is and transfer it up and down a piece...or transfer it to a marking gauge.

It's not arbitrary just to make everyone's life hard.  It's the way it is because it makes things EASIER, and the imperial UNITS are also intelligently designed to be easy to work with.  12" in a foot is easily divided into 1/2s, 1/3s and 1/4s.  Quite convenient, no?  It's traditional to build Classical guitars using metric measurement, though it's traditional to build just about every other guitar with imperial measurement.  All of the classical builders I know talk in metric units, but say things like, "Oh...that's about 22 1/4mm....maybe 22 1/3mm at the most"....and then they have to convert the fraction to a number to look it up on the stupid metric ruler that is pretty much unavailable with fractions on it.  That's reality.

Metric and decimals are great when you're constantly converting back and forth between different units and you need to know things like how much cement do you need to support a swimming pool of a certain size.  Nice not to have all these crazy factors kicking around.  That's not a common everyday task.  Imperial measure, and also the fractional system that is traditionally used, is designed around people eyeballing, chopping things in half or thirds, and things like that.  It's a very practical system.

It's also why we still use nautical miles.  It's supremely convenient for doing calculations in your head.  It's also why people working with optics often use arc-seconds.  It's amazingly powerful to do back of the envelope calculations in your head.

[Rigby]

Don't confuse measurement system merit discussions with all of the benefits that come with standardization.

[John Coloccia]

Personally, I wouldn't mind if the US went all metric.  I work in both system interchangeably.  The reasons we haven't moved yet are a lot more deeply seated than simply cost or stubbornness.  That's my point.  There's a ton of engineering work that's already done in metric.  Any of my new mechanical designs where it's convenient is designed in metric with metric hardware.  I wouldn't mind as good first step to make gallons and miles disappear.  There's little value in converting between gallons and, say, tablespoons, for example, and little value in converting from miles to feet or inches, so it would be no big deal to start converting gallons and miles to liters and km/h.

I have little doubt that the inch will still be going strong long after I'm gone.

[jlmoon]

Just about punched a hole in my LCD (plastic) screen trying to mash "GeoffS's" bug icon.. 

[zapta]

Just about punched a hole in my LCD (plastic) screen trying to mash "GeoffS's" bug icon.. 

I assume it's not a self portrait.  ;-)

[jlmoon]

lol.. nah.. go check out his icon/avatar.. animated gnat .. fooled me eyes for a sec

[SeanB]

I have learned to ignore it.........

[jlmoon]

yes.. I as well!

[ajb]

Well even if you don't want to change to metric. Do you think it is a better system?

For some fields, such as science and 'abstract' engineering, sure.  For everyone else, not particularly.  For most purposes the better system is always going to be the one you're more comfortable with, both in ability to calculate and in ability to grasp the actual magnitude of the units.

I for one really don't want to take two sets of spanners, two sets of Allen keys to a job. You surely will admit there is a cost in this.

  Sure.  So let's immediately stop producing new designs in imperial and make everything in metric instead.  Now that's done, all you need to take to a job is. . . .both sets of tools because there are still millions of pieces of equipment in the field that were built with imperial fasteners.  How long do you expect it to take to naturally cycle out even a small fraction of the imperial fasteners in the field before you can confidently take only one set of tools on a service call?  Decades, surely.  In the mean time, you'll keep carrying two sets of tools and factories will continue to churn out imperial fasteners as spares if nothing else.  Now that we've spent billions of dollars to change tooling, when does switching to metric start saving us money?  For better or worse, people have a hard time planning on that time scale, especially when the upfront cost is so massive and any reward so distant.

As far as changing over, you are already doing it, but some of you haven't noticed.

Indeed.  I see metric dimensions on more and more building materials, enclosures, and so on.  Globalization helps with this, as more companies outside the US supply goods here and as US companies sell more goods overseas it only makes sense to adopt the more common units in your marketplace.  Ballpark, I'd say in another 50-100 years at the current pace the US will be where most other countries are now--metric used almost everywhere except in a few persistent traditional areas.  Maybe even longer with things like lumber where there's so much inertia in the trades and building codes built up over a hundred or more years.

[SeanB]

I have the metric and imperial tools, and use them a lot. Some machinery I work on was designed a century ago, and has remained basically unchanged since then, with spare parts from the originals still being made.  Of course the country of origin changed from USA to Mexico, then China and now India, always chasing lowest cost. User price though always has a nasty tendency to rise though. It was cheaper for many parts to simply have them made locally in an engineering shop, and they came out as better quality and a lot faster than the OEM parts to get back into service.

[SirNick]

All of the classical builders I know talk in metric units, but say things like, "Oh...that's about 22 1/4mm....maybe 22 1/3mm at the most"....and then they have to convert the fraction to a number to look it up on the stupid metric ruler that is pretty much unavailable with fractions on it.  That's reality.

You know woodworkers that speak in "about" fractions of a millimeter.  As an eyeball figure.  Y'know, give or take a few micron...   

The reason fractions are so useful in Imperial measurements is because we lack a system that makes it easy and convenient to jump to the unit that most accurately portrays scales of a base unit.  You can have a plank of wood that is a meter long, and fine-tune that with as many millimeters as it takes.  Or centimeters and then millimeters.  They're all directly and trivially comparable.

OTOH, what's the equivalent of 1mm in fractions of an inch?  Which is really easier to measure and comprehend?  3.001 meters?  Or 1 yard and 13/32"?

This isn't about gimmicky comparisons like the number of soda cans it takes to fill an amusement park aquarium.  There are real-life advantages too.  I've used Imperial all my life and I still can't immediately visualize how many yards are in a mile.  Why would that matter?  I dunno.  Imagine a construction job laying fiber optics, that come in meters, and knowing how many km you need to go.  Imagine the same with spools of 1000 feet and distance in miles.  Ugh.  Not rocket science, but not something you're likely to be able to pull off the tip of the tongue either.

b) The argument always assumes it has to be done as a big-bang. Which is not true. You can gradually change. Actively taking up opportunities, instead of working twice as hard to ignore opportunities.

Exactly my point.  No need to throw out all your old Imperial tools wholesale, that's a nonsensical way of thinking.  Just buy a metric one (if you don't already have it anyway...) and start using that for the easy stuff.  Progressive conversion.  Piece of cake.  Crises averted, and the rest of the world can stop catering to our whims.  (There's your opportunity cost BTW.)

[SirNick]

How long do you expect it to take to naturally cycle out even a small fraction of the imperial fasteners in the field before you can confidently take only one set of tools on a service call?  Decades, surely.  In the mean time, you'll keep carrying two sets of tools and factories will continue to churn out imperial fasteners as spares if nothing else.  Now that we've spent billions of dollars to change tooling, when does switching to metric start saving us money?  For better or worse, people have a hard time planning on that time scale, especially when the upfront cost is so massive and any reward so distant.

It entirely depends on what your vocation is, I suspect.  Farm equipment?  Maybe a couple decades.  Computers?  Probably by the end of the decade.  There are opportunities with enough turnover that it really doesn't matter if you switch tooling, because you're going to be spinning new designs anyway, and that's going to be the most expensive part of the bargain.

Besides, that "how does it affect ME, NOW?" attitude is one of mankind's greatest faults.  I guess you could leave this mess for later generations to sort out, when the world has become even smaller.  Or you (not "you" you, but "us" you) could man up and take steps reduce the wasteful redundancy over the course of a lifetime.  Little things can mean a lot, eventually.  It doesn't hurt too badly to do the right thing, even if you never live to see the benefit.

[John Coloccia]

OTOH, what's the equivalent of 1mm in fractions of an inch?  Which is really easier to measure and comprehend?  3.001 meters?  Or 1 yard and 13/32"?

Why would I ever convert fractions of an inch to mm?  If I was working in mm, I'd work in mm.  If I'm working in decimal anything (imperial OR metric), then I work in decimal.  If I'm working in fractions, I work in fractions.

Imperial does not mean fractions.

Anyhow, if you're comparing a bunch of pieces of wood, and all of them 1 yard and a few 32s of an inch, then it's much easier to quickly split differences using the leftover fraction, actually.  Again, for this and other reasons, many trades have stubbornly stayed with fractional measure.  The inch unit is also particularly convenient for a LOT human sized things.  Guitars....clocks....forks....bowls....shoes....etc.  They are all very conveniently described with small numbers....a few inches wide....15 inches long, etc.  These measures all came about based on the practicality of eyeballing things and quickly dividing them up in your head.  Given something that's about a foot long.....say, the average foot wearing a shoe, for example, it's downright trivial to subdivide that into inches by simply continually chopping it in half.  Any mistake is immediately apparent.  I'll bet you that I could subdivide by hand and by eye down to 1/64" with wicked accuracy because the human eye is particularly good at doing such tasks and seeing small differences in intervals.  I would never do that, but this is the basis of the system....basic measures that easily subdivide into other, useful measures.

But anyhow, over here we seem to be able to work in whatever system suits the situation best.  Given the prolific and world class science and engineering prowess that the US possesses, the notion that this metric/imperial thing is somehow an impediment seems not to be accurate.     It just doesn't seem to be a big deal.  Someone will undoubtedly bring up some satellite that crashed because of a conversion between metric and imperial, but it could just as well have crashed converting from meters to kilometers.  Why would anyone ever specify a design in mixed units?  Poor design is poor design regardless what country you happen to live in.

I see that a lot too, though.  Tons of projects are designed in inches, using metric hardware.     Seems looney to me, constantly converting back and forth to get clearance holes sizes and things like that.  THAT I'll never understand.

[SirNick]

OTOH, what's the equivalent of 1mm in fractions of an inch?  Which is really easier to measure and comprehend?  3.001 meters?  Or 1 yard and 13/32"?

Why would I ever convert fractions of an inch to mm?  If I was working in mm, I'd work in mm.

You wouldn't.  My point was that the Imperial system doesn't scale well below an inch.  There's no common, vernacular unit of measurement for small portions of an inch, except for... well... "portions of an inch", whether that be fractions or decimal.  Yes, in engineering we use "thou" or "mil"... but say that to a pedestrian and they'll think thou speaketh oddly, or in metric.  In (actual) metric, you've got mm right there.  No need to resort to fractions.  Not that fractions are hard per se, or unique to Imperial, but they are the de facto way of discussing things smaller than an inch.  Furthermore, if a mm is too big, there's another SI unit below that.  And one below that.

Imperial does not mean fractions.

*I* know that, but you have been championing Imperial for its convenient application in wood-working, specifically because of rulers and their fractional units of measure.  (Which is tied into the argument above, about there not being a common sub-inch UoM.)

The inch unit is also particularly convenient for a LOT human sized things.  Guitars....clocks....forks....bowls....shoes....etc.  They are all very conveniently described with small numbers....a few inches wide....15 inches long, etc.

They are equally convenient in metric, if you have a good frame of reference in metric.  As an American, I don't.  Oh well, learning curve.  However, I know that an inch and a cm are close enough that I can get a (very) rough idea of how big something is by equating it in inches.  It's not 1:1, but if cm is the right scale, I know if we're talking about a grapefruit size object or a house size object.  So what's wrong with measuring forks and shoes in cm?

But anyhow, over here we seem to be able to work in whatever system suits the situation best.  Given the prolific and world class science and engineering prowess that the US possesses, the notion that this metric/imperial thing is somehow an impediment seems not to be accurate.

World-class, maybe.  But not unique.  And the foreigners are gaining on us.  If you were insert-European-country-here, and you could buy a widget from the US, or an equivalent widget from, say, Singapore, except that it would be in your native unit of measure, why would you buy the Imperial one?  (That's not even considering the price disparity.)  America is on the verge of losing its place of dominance.  We should be doing everything we can to be competitive in a global marketplace, and using a proprietary unit of measure is not going to do us any favors.  It isn't 1970 anymore.

[IanB]

There's a lot of vagueness in this thread about "metric" and "imperial", and that itself indicates a source of confusion.

The USA does not in fact use the imperial system (which is used in the UK), it uses the U.S. customary system of measure. There are differences in how things are defined, most notably in fluid measure (where fluid ounces, pints and gallons are different sizes).

There are also various different metric systems of measure in use around the world, some of which relate to SI, and some which do not. (For instance in Japan it is customary to measure pressure in kg_f/cm², which is not an even multiple of the pascal or N/m².

Systems of measure are used in two ways: (1) for specifying and measuring dimensions, and (2) for doing engineering calculations.

For specifying and measuring, any agreed upon system is as good as any other.

For calculations, this is not the case. If the system of measure is not internally consistent then various odd conversion factors will appear in formulas everywhere, conversion factors that you have to look up or memorize. For instance, how many ft-lb_f/s are there in 1 hp?¹ This conversion factor will come up if you do a compressor power calculation involving pounds per square inch, cubic feet per minute, and horsepower (not to mention seconds in a minute and cubic inches in a cubic foot).

This is so much the case that engineering software typically will do its internal calculations in SI and convert units of measure on input and output.

¹ There are 550 ft-lb_f/s in 1 hp

[HackedFridgeMagnet]

As a matter of interest, what do they use in Britain and US for land areas smaller than an acre?

The old title for my land says something like 1 acre, 3 rood, 7 chains and I forgot whats after that, maybe it was square feet. WTF!
How did they ever work with that?

Luckily when the council recalculated the area they came up with 0.6 hectares but I think it is nearer 0.8. Hopefully I am paying less council rates because of it.

Those units rood and chains really had to go.

[John Coloccia]

They are equally convenient in metric, if you have a good frame of reference in metric.  As an American, I don't.  Oh well, learning curve.  However, I know that an inch and a cm are close enough that I can get a (very) rough idea of how big something is by equating it in inches.  It's not 1:1, but if cm is the right scale, I know if we're talking about a grapefruit size object or a house size object.  So what's wrong with measuring forks and shoes in cm?

There's nothing at all wrong with it.  Metric is fine system.  The point that I'm making is that the system isn't "crazy".  The fractions come about specifically because the various units conveniently divide into 2's and 3's, which is convenient for estimating by subdivision by 2s and 3s...something which is easy to do by eye, and also easy to do in your head.  It's a very useful and well thought out system for what it is.

[staxquad]

There's a lot of vagueness in this thread about "metric" and "imperial", and that itself indicates a source of confusion.

The USA does not in fact use the imperial system (which is used in the UK), it uses the U.S. customary system of measure. There are differences in how things are defined, most notably in fluid measure (where fluid ounces, pints and gallons are different sizes).

There are also various different metric systems of measure in use around the world, some of which relate to SI, and some which do not. (For instance in Japan it is customary to measure pressure in kg_f/cm², which is not an even multiple of the pascal or N/m².

Systems of measure are used in two ways: (1) for specifying and measuring dimensions, and (2) for doing engineering calculations.

For specifying and measuring, any agreed upon system is as good as any other.

For calculations, this is not the case. If the system of measure is not internally consistent then various odd conversion factors will appear in formulas everywhere, conversion factors that you have to look up or memorize. For instance, how many ft-lb_f/s are there in 1 hp?¹ This conversion factor will come up if you do a compressor power calculation involving pounds per square inch, cubic feet per minute, and horsepower (not to mention seconds in a minute and cubic inches in a cubic foot).

This is so much the case that engineering software typically will do its internal calculations in SI and convert units of measure on input and output.

¹ There are 550 ft-lb_f/s in 1 hp

In Canada, we are caught between the USA and the UK for ancient measures.  When someone discusses gallons, we have to specify American gallons or British gallons knowing that American gallons are smaller with 128 ounces and British gallons are larger with 160 ounces, but darn garnit, it's so f-ed up, even the ounces aren't equal, so basically you have to just take it for granted that you get more with British gallons and get less with American gallons, and we thank the goodness of foresight for liters.  (when we buy milk we get 3 small clear bags of milk in a 4 liter carry bag {it's slightly less than a US gallon}  Nobody really knows the exact volume of one little clear bag of milk, except 4/3 liters.)






 

[IanB]

I've never seen milk sold in plastic bags before. However do you serve it? Do you pour it into a jug and keep washing up the jug?

[staxquad]

I've never seen milk sold in plastic bags before. However do you serve it? Do you pour it into a jug and keep washing up the jug?

[John Coloccia]

Now THAT I've never seen before.

[GK]

Metric and decimals are great when you're constantly converting back and forth between different units and you need to know things like how much cement do you need to support a swimming pool of a certain size.  Nice not to have all these crazy factors kicking around.  That's not a common everyday task.  Imperial measure, and also the fractional system that is traditionally used, is designed around people eyeballing, chopping things in half or thirds, and things like that.  It's a very practical system.

Do you remember those things called multiplication tables, that they used to teach by rote?

1,2,3,4,5......
2,4,6,8,10,12.......
3,6,9,12,15,18,21,24,27,30........
4,8,12,16,20,24..........
6,12,18,24,30.........
9,18,27,36,45.......
etc..........

Make it mindlessly easy/practical to divide crap into finer fractions than just half’s or thirds........
Of course difficulty arises trying to think of imperial measures in metric terms, but nobody working with the metric system proper works in multiples or sub multiples of 25.4mm, feet or yards. I think your argument is full of crap.

[vk6zgo]

[/quote]

In Canada, we are caught between the USA and the UK for ancient measures.  When someone discusses gallons, we have to specify American gallons or British gallons knowing that American gallons are smaller with 128 ounces and British gallons are larger with 160 ounces, but darn garnit, it's so f-ed up, even the ounces aren't equal, so basically you have to just take it for granted that you get more with British gallons and get less with American gallons, and we thank the goodness of foresight for liters.  (when we buy milk we get 3 small clear bags of milk in a 4 liter carry bag {it's slightly less than a US gallon}  Nobody really knows the exact volume of one little clear bag of milk, except 4/3 liters.)


[/quote]

Converting UK to USA is often confusing because they use the same term for different quantities,& have totally different standards in such things as screw threads.

In Oz,we often had British equipment with BA ,BSF,& Whitworth screws sitting side by side with US sourced stuff using those funny screws that seem to have no known non-US equivalent-----Tektronix are full of them!

Australian made stuff usually used UNF or Whitworth & BA.
Of course,UNF are one bright point as they are used in both the UK & USA.

To anyone living outside the USA,this variation in Imperial/Customary hardware is a potent reason for going to metric.

Even between non-metric countries,it is more convenient for,say,the UK to export stuff in 200 litre drums to the USA,as each side only needs to do one well known conversion,whereas it may not be immediately obvious that a "44 gallon" drum is equivalent to a US "55 gallon " drum.

Back in the day,Australians would be bemused by the difference in mpg figures for US made cars,between local & US Road tests.
In the same way,Americans would be disappointed by the seemingly poor mpg they got from British cars,compared to UK Road Tests.