Imperial units of measurement and the future?

A "relatively small proportion" of a vast market is still a very large number - and I note that all the mainstream electronics component suppliers are still selling the full range of DIL sockets on 0.1" pitch, including RS components, who don't stock any line unless they can shift it in bulk.

As for the 3 foot gauge, of course the Irish gauge came out at 914mm - because 36 x 25.4mm = 914mm! As for the Swedish 3 foot gauge, that was because the old Swedish foot was smaller than ours - but I fail to see what that has to do with the use of Imperial measurements on our railways. And, as I pointed out above, most of the railways in Europe run on the same standard gauge as do ours - and I can't see that many thousand miles of track being changed in the foreseeable future.

But I've said my piece; feel free to describe it as "total rubbish", if you wish. I couldn't give a monkey's.

 

Actualmy a centimetre is one billionth of the distance from the equator to the north pole....or at least that's how it was designed in 1793....

 

Actually a centimetre is one billionth of an incorrect attempt at calculating the distance from the equator to the north pole. Vive the bloody french

 

The original quote was:

Which is blindingly easy to show is simply not true, every integrated circuit does not have its legs on 0.1" centres, in fact you'd probably find more produced that don't these days than those that do. ...just flicking through your RS catalogue will show the statement wasn't true (not that RS is a particularly 'go to' supplier in industry).

Even going back into the mists of time, some integrated circuits were produced in TO-18 style metal can packages, which also aren't on 0.1" centres, so isn't even a case that it used to be true, but isn't any longer. As for selling DIL sockets... err, well seeing as those are designed for DIL package ICs, you'd rather expect them to be in the same size. However it is increasingly common to find manufacturers no longer supplying newer designs of IC in DIL packages, there are simply better alternatives. (including SOIC, which actually still is an imperial pitch, just not 0.1").

Bit of a shame to make such an obvious false claim, because electronics is actually a very good example of where both measurement systems are used in harmony every day without the sky crashing down and people failing to understand or cope - manufacturer's will quote 6 thou track & gap manufacturing tolerances, even if that gets converted to metric for DRC checks. Connectors may be on 0.1" pitch, but with 0.95mm holes...

 

Yeah, quite amusing that.
The more modern attempts to try and make it mean something aren't much better. I think the current claim is that it's an arbitrary constant fraction of the distance traveled by light through a vacuum. ...divide that distance by a different constant and suddenly an inch can be defined in the same way as well. I think prior to that it was the wavelength of light from something or other multiplied by a different constant to make it equal the 'metre standard' bar. Once again, multiply it by a different number and it can be used to define the distance of anything, and thus you can claim any measurement system is derived from scientific standards! Lol.

<quick google>

Yeah, currently it is the distance light travels through a vacuum in 1/299,792,458 of a second.
....that nice "metric" based constant, rather than using some system based on obscure fractional numbers! lol

 

. . . except that the 'designers' got their calculations wrong, so the centimetre is even more arbitrary a measurement than an imperial inch, because it doesn't actually relate to anything. Even at that stage of scientific knowledge, they should have been humble enough to realise that the chances of them calculating such a measurement with even approximate accuracy were as near zero as makes no odds.

 

Let's do without harrumph please.

PH

 

As a decorator, when wallpapering and using a yardstick (which are now metre sticks) I work in metres and inches.
Still cannot get to grips with French inches and gallons

 

Because of the xenophobic undertones.

PH

 

The advantage of SI units (specifically SI, not metric) is that with one exception they are derived from fundamental physical properties (so are invariant and unambiguous); and that having defined seven fundamental properties (mass, length, time, temperature, electrical current, light intensity and a number, mol), all other units of measure can be derived from those seven without needing arbitrary constants. For example, as far as is known, the speed of light in a vacuum is a constant across the universe and therefore it makes more sense to define length based on that constant than trying to maintain some metal bar in constant conditions with unknown physical and chemical degradations going on over time that remove the certainty that it remains a constant length. Thus for scientific calculation purposes, SI units lead to significant simplification and clarity.

For everyday use, I can see the advantage of using which ever system you are familiar with. So for example, if driving a car I may well think in terms of miles per hour. But if someone posed the question about what the ultimate thermodynamic efficiency of a car was driving at a given speed and using a given amount of fuel of known molar energy density, I'd rapidly convert everything to SI units before attempting the calculation.

Tom

 

Vehicle tyres must be the most common illogical mixture of measurements, whether it's 80/100-21 on a motorbike, 195/70R14 on a car or 295/80R22.5 on a truck, that's a wonderful combination of metric, percentage and imperial measurements on one item.
British Association threads are hard to beat too, where they start off well enough with 0BA being 6mm diameter and 1mm pitch, but then each increasing number size is 0.9 times the size of the preceding number, rounded to two decimal places, converted to imperial, then rounded to three decimal places.

 

Courtesy of decades of modelmaking, I can readily convert between imperial and metric, but only because I've a reason to do so. Even then, dividing (say) 9'-33/8" by 76.2 to get a meaningful answer in inches or millimetres is a lot dafter than working from 4mm/ft with historic subjects. In any event, I tend to produce any required drawings at 12mm/ft and reduce 'em .... it's both easier on the eyes and rather less inaccurate. As speadsheets can be created with all manner of embedded equations (e.g. to convert feet & inches into millimeters, or furlongs per fortnight into metres per second) I don't get unduly hung up on nomenclature, after all this time, it's an automatic process anyway.

I think 'tea' in cuppas, 'filler' in smidges (if you need to go to oodles, let alone shedloads in 4mm scale, there's something drastically wrong!), 'temperature' in celcius and 'beer' in pints, but am just as happy with my degrees in 'Kelvin' or beer in 'litres'..... especially beer in litres.

Oh aye...... and a template is a template is a template. It's either accurate or it isn't .... whether imperial or metric! Did anyone mention tolerances?

Here endeth the missive.

 

My view is that we are where we are.

I work with railway vehicles mostly built pre- metrication. I also work on newer vehicles built to metric dimensions.

I use either system equally well plus conversion factors.

I object to people trying to “metricate” an item from the 1950s because they don’t like or cannot use their 12 times table and fractions. Let alone convert between thou and fractions.

People who try to and sometimes manage to dog a metric nut onto a bsw thread are not welcome.

 

Yes. I believe Paul and Ralph are discussing it 'up-thread'!

 

I'm another worker in a mixture of SI, metric and UK imperial measurements, depending on what I'm working on / restoring.
Most of the early wooden carriages are "interesting" and I'm quite convinced that one we've been working on was built by two teams of joiners that didn't speak to each other, nor did they work to the same drawings ... yet another carriage was clearly jig/bench built and then assembled on a "production line". Another "niggle" has been the use of iron pins in joints, rather than treenails ...

Unfortunately, timber changes shape a lot more often than metal ... frequently I'll dry build something during the week, take it apart overnight / the weekend and find the next morning (especially Monday) the *&^% joints don't fit anymore.
Has anyone else found that annoying tendency that stuff (usually wood) has to "grow" a bit overnight ... currently wanting to "speak firmly" to some framing joints (which also need a soak in a timber treatment). That will have to wait until I've finished this mug of coffee !

 

Going back to the original question of children being taught in metric, then having to learn imperial measurements on the remote chance that they end up working somewhere in the heritage industry, this isn't all that different to the far more common problem of children being taught in centimetres, then going out in to the real world where everyone uses millimetres.
Why do schools do that? If kids are growing up in a world of 12mm ply and 8mm bolts, why teach them in units they will probably never use?

 

Several of our EHSI trainees have had exactly this difficulty ... having being taught in metric and then working in imperial (and on timber, which has a nasty habit of altering when the humidity flips!).
Also applies to suppliers, materials are frequently delivered as the nearest metric equivalent to the specified imperial dimension.

 

Or, in chemistry at uni, being used to measure things in grams in teaching labs and then having to get to used measuring things in milligrams in a research lab. The BSc student was recently looking on one or two occasions got confused and rather than measure out say 12mg, measured out out 1.2mg and then wondered why the NMR spectra looked very weak.