Metric vs Imperial – Practical or Traditional?

[Chris TriceParticipant @christrice43267]

The other story I tell purely for interest was I did a film in Montreal, the most French quarter of Canada eleven years ago. Although the inhabitants in and around Quebec represent only ten percent of the Canadian population, they fiercely insist that much of Canada is bilingual such as road signs being in french and english across the entire country. I took all my metric taps and dies assuming that metric nuts and bolts were going to be the norm. I was`stunned to find that even there, they were still using archaic imperial threads and it was actually a struggle to find metric machine screws at all. I remember explaining to the Canadian crew how the metric system of screw threads worked and even they said what a brilliantly simpler system it was.

[Martin WParticipant @martinw]

Andrew

 

Using the nautical mile while travelling due north/south on the meridians or perhaps east/west on the equator (well nearly) is fine but out come the sine/cos tables for trogging around the latitudes !   Thankfully when they moved from the millibar it went to a direct equivalent of hPa otherwise there would have been trouble at the mill as they say .

 

Cheers

 

Martin

 

PS

 

Terryd.

 

  I use metric and can best your age by some 3 plus years, must be the old dogs and new tricks syndrome or something to do with the number of fingers plus thumbs I have. Fingers only and your into octal and that takes me back to the first mainframe system I worked on.

[Anonymous]

Martin,

 

Of course you are correct about needing spheroidal geometry, but aeronautical charts on a small scale, say southern England, have a distortion such that distances and true headings are correct within the normal navigation limits without the need for trigonometry. Any map must have a distortion, as it is a flat sheet representing a near spheroidal shape, but some distortions are more useful than others. I’m not sure if the CAA charts use Mercator or Lambert mapping; my southern England chart doesn’t say.

 

Regards,

 

Andrew

[Ian S CParticipant @iansc]

Andrew, if the british maps are the same standard as our NZ ones, they will beTransverse Mercator projection. he altitudes are in colours, in whole hundreds of feet, and the meters as conversions of those feet. Distance is in nautical miles, with a metric scale included. Runway lengths in feet. Mind you this may not be fully up to date, my newest map is dated 1980, but NZ was well into metrics then.Ian S C

[TerrydParticipant @terryd72465]

Hi Chris  (Stevens),

 

It was not only the British and Americans who made steam engines etc in the past.  The ‘Continentals’ made them too and they were mostly Metric.  We would also have used metric if the decision made in the 1870s for the UK to adopt the system had been followed through.  As for the literary references you make, I hope that you really think that the metric system is somehow thought up by some eccentric individual.  It is a very carefully developed system based on natural phenomena and governed by the Conference which represents almost 80 nations.  The metre was originally based on the length of a meridian of the Earth, The gram is the weight of one CC of pure water at a given temperature.  I personally think that is better than a system based on grains of Barley.

 

As for the changes in the system,  the SI standard now used was adopted in the 1960s to overcome the problems of the differences between the scientific and engineering systems.  The Imperial system was not impervious to change.  I remember the fps system which added the poundal and later the slug (and slinch). Frank Hornby (the developer of Meccano) wanted to use the metric system as the basis for his invention but was foiled by the lack of availability of metric components in the UK so he had to use an imperial system.  His later developments used metric

 

 For those Francophiles amongst us, a decimal system based on a universal measurement (as the Metric system), to replace the ad hoc inch/foot system, was first proposed formally by an Englishman (Wilkins) in the second half of the 17th century.

 

As far as the USA is concerned, remember that NASA uses the SI metric system, as does the scientific community

[John OlsenParticipant @johnolsen79199]

Having just been playing with some Imperial drawings…if Imperial fractions are so useful and versatile, why was it necessary to invent not one but two separate measuring systems for the  sizes of drills and of wires (and sheet material). 

 

So when I want a hole to take a certain piece of wire, I have to go and look up the SWG chart, find the size, then go and look up the drill chart, and find the number of the drill that will make a hole that the wire will fit in.

 

The same applies of course with BA screws, although at least there if I am working in metric I can find the diameter by multiplying 6mm by 0.9 to the power of the BA number.

 

Imperial fractions might be good enough for carpentry but they are just a mess for serious precision work.

 

regards

John

[TerrydParticipant @terryd72465]

Tell me, as you want to be in the 21st Century, I must assume that you only make models of Nuclear Power Stations or Fuel Cells or some other “modern” stuff, and never touch anything related to steam engines or other old technologies.

The trouble with being modern is that modern keeps changing, even the metric system.

Hi Again Chris,

 

Sorry to become boring,  but it is not only the ‘modern’ which is changing.  Things changed very quickly in the 18th and 19th century.  In fact it was probably changing faster in the Victorian than in our present era.  Also we make much more than ‘Nuclear Power Stations’ nowadays.  With respect, it seems to be a particularly blinkered point of view that you are taking on this

 

Terry

[Sub MandrelParticipant @submandrel]

Reading Watt’s autobiogrpahy again last night. Apparently he advance the decimal

sub-division of the foot, shortly before the French came up with the metre.

 

The British get their first again

 

Neil

[chris stephensParticipant @chrisstephens63393]

Hi Terryd,

Not blinkered, I just don’t like change.

I have just had a bereavement and seem to have lost interest in game playing, so bye for now.

chriStephens 

[Chris TriceParticipant @christrice43267]

Sorry to hear of your loss. Some things are more important than discussion forums.

 

 

 

 

“I just don’t like change.”

 

Which reflects those examples from history but it’s natural for people to feel what they feel.

 

But the essential truth is that inescapably, imperial is inexorably approaching a slow sunset. Sooner or later, an increasingly older and ailing head of the herd will succumb to the rising stronger contender more fit to lead.

 

 

[Peter G. ShawParticipant @peterg-shaw75338]

I haven’t entered these discussions before, but I have been following with interest. I have to say though, that I think that certainly for the UK, Chris Trice has hit the nail on the head with his last paragraph.

 

UK people who refuse to move to metric are simply bashing their heads against a brick wall. Metric is here for the vast majority of purposes, and we all do need to get a grip on it. It is true that Imperial may remain in certain limited instances for some time yet, eg travel distances, but I wouldn’t want to bet on it remaining so.

 

Imperial will also remain in the repair field where it is impractical to use metric until such time as all non-metric equipment has finally bitten the dust. New build using imperial measures will eventually become, much as they are already, specialist builds done mainly as a hobby.

 

Finally, may I say that I grew up as an imperial child, although I never really got to grips with adding fractions together to create a third fraction. Don’t get me wrong – I could do it, but not in my head. Then maybe 30 years ago, I specifically constructed a wall-cupboard using metric only. That was my conversion. Taking up model engineering, I specifically bought metric equipment. I do though,  have an imperial micrometer which was bought specifically for measuring shims on the tappets of my Maxi. Now though, metric has more or less become automatic 1st choice for me.

 

Regards,

 

Peter G. Shaw

 

 

[TerrydParticipant @terryd72465]

Chris,

 

Sorry to hear that,

 

please accept my heartfelt condolences  I Look forward to hearing from you soon,

 

Best regards

 

Terry

[Sub MandrelParticipant @submandrel]

Sorry to hear of your loss, Chris.

 

Other Chris: But the essential truth is that inescapably, imperial is inexorably approaching a slow sunset.

 

I have read thirty year old articles announcing the iminent demise of imperial and saying that model engineers had better get switched ASAP…  it will be a very SLOW sunset

 

Neil

[Chris TriceParticipant @christrice43267]

Slow initially but like all sunsets, the last glint above the horizon is quickly gone. We are the last generation. After that, it’ll only be important to those desperate to hang onto the past which represent a tiny fraction of a percent of the population. One may have good or bad feelings about this but it remains a reality. If you analyse it truly dispassionately and without the happy memory emotion, imperial is a barmy system. We count, calculate and express numerically in decimal throughout the entire world. Everyone ‘gets it’. We don’t count in base 12 or base 16 or base 20 or base 32 etc. Imperial is not a decimal system except when an inch is divided up into thou’s. And a thirty year old article is jumping the gun given that imperial was still a major player in 1980 but its demise is now in view.

[Dinosaur EngineerParticipant @dinosaurengineer]

Chris Trice,

I’ll bet you a £1,000 ( sterling) that the imperial system is still in use after your life time & mine.

Seriously though because of the legacy products that need support and also in specialised applications the imperial system will be used for far longer than you imagine . Most of industry changed over to the metric system some time ago but they still have to maintain & adhere to imperial standards that have been in use for many years if they want their products to be compatible with the existing user base.

Most PCs ( all ?) still have connectors with 4-40 UNC screw fittings and this is the industry that has adopted more changes over the years than most others .The imperial system is not just about measurements but also international standards.

I remember some Japanese test equiptment that was incompatible with international connection interfaces and the Japanese company had to change from their metric connector fasteners to the international imperial fixings .  

Edited By Dinosaur Engineer on 03/11/2010 16:47:50

[KWILParticipant @kwil]

So NASA use metric, strange, who screwed up the Hubble Telescope  then?

[David Clark 13Participant @davidclark13]

Hi Kwil

Any engineer with a set of Metric spanners could have done it.

regards David

[TerrydParticipant @terryd72465]

Posted by KWIL on 03/11/2010 16:33:33:
So NASA use metric, strange, who screwed up the Hubble Telescope  then?

 

Probably one of NASAs contractors who sometimes still work in Imperial units. 

 

Here’s a quote from NASA – “The confusion that can arise from using mixed units was highlighted by the loss of the Mars Climate Orbiter robotic probe in 1999, which occurred because a contractor provided thruster firing data in English units while NASA was using metric.”

 

BTW the moon is going metric too.  See the NASA Science Web News.

 

Hi Stub, 

 

You have to remember that 30 years ago industry here in the UK  as well  schools and colleges were unloading countless tons  of imperial manual equipment and tooling in the wake of metrication and NC (and CNC) initiatives.  That situation will never arise again unfortunately, and without a supply of spares the end will be nigh.

 

Terry

Edited By Terryd on 03/11/2010 17:13:12

[Anonymous]

Not all D-type connectors are 4-40UNC, you can get the fittings in M3, I think, but the vast majority are still 4-40UNC. Only last week I hand tapped a load of 4-40UNC holes for some prototype boxes that use D-type connectors. Actually the screw fittings are a PITA. They’re usually nickel plated brass. As you tighten it up, just a little more and it’ll be snug; then ping, the damn thing breaks at the base of the thread.

 

All this mention of sunsets brings us on to another point. What is time if it isn’t an imperial measure? Sixty seconds in a minute, sixty minutes in an hour, 24 hours in a day, anything from 28 to 31 days in a month, 365.25 days in a year for goodness sake! It’s just crying out to be metricated.

 

Regards,

 

Andrew

[KWILParticipant @kwil]

Very droll David.

 

NASA. it is not the mixed Data or WHY, it is a question of not questioning what you have been given. Even if you work in Metric, you should still check it out!

[John OlsenParticipant @johnolsen79199]

Apart from time we also have degrees, minutes, seconds which go back to the  Babylonians. The maths types try to push the use of radians, but I have yet to see them used for real engineering work. There was also the Grad, but that never seemed to get any real use. (100 grads make a right angle. )

regards

John

 

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Andrew, I’m not totally sure, but I think a study of metricating time was done many years ago, but for some reason or other it wasn’t a viable or practical idea. Not sure if it was something to do with a year being actually 365 .25 days long, hence the leap years. But of course we now know that time is not truely constant either.

 

Regards Nick.

[Sub MandrelParticipant @submandrel]

There are those who advance 10 hour days with 100 minutes of 100 seconds.

 

Those who worship the millimeter ought to welcome such a system with open arms!

 

The use of arcane units is not necessarily a barrier to understanding. Apparently the basic match skills of far-eastern farmers are far ahead of those of western ones, because they have to deal with the greater complexity of rice farming.

 

And Terry, yes there won’t be a metric give-away because they never replaced the imperial stuff

 

Oh and the problem with hubble wasn’t wrong units, it was an error in calculating the mirror dimensions AIUI.

 

Neil

Edited By Stub Mandrel on 03/11/2010 20:27:04

[TerrydParticipant @terryd72465]

Posted by Stub Mandrel on 03/11/2010 20:25:59:
………they never replaced the imperial stuff …………….

 Yes they did, I worked both in industry and education in those few years of the changeover.  OK it wasn’t given away, but it was sold, I know, I bought quite a lot of it and sold it at a good profit to the Luddites.

 

Terry

[TerrydParticipant @terryd72465]

Posted by Andrew Johnston on 03/11/2010 17:27:54:

All this mention of sunsets brings us on to another point. What is time if it isn’t an imperial measure? Sixty seconds in a minute, sixty minutes in an hour, 24 hours in a day, anything from 28 to 31 days in a month, 365.25 days in a year for goodness sake! It’s just crying out to be metricated.

 

Regards,

 

Andrew

 Hi Andrew,

 

You’re not talking about metrication, but about decimalisation,  Which if I remember was going to cause the end of the world as we know it on Feb 15th 1971 when our currency was decimalised 110 years after it was proposed!  I’m still waiting for Armaggedon.

 

To quote the Department for Industry report 1862-

 

“In 1862, the Select Committee on Weights and Measures favoured the introduction of decimalisation to accompany the introduction of metric weights and measures”

 

Sleep tight

 

Terry

Edited By Terryd on 03/11/2010 21:29:22

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