Imperial v Metric Measures

Perhaps Dave was using the modern definition of engineer, which seems to be somebody with a bent screwdriver and a hammer who can't fix your washing machine.

Lots of things wrong with that.

- it's eminently clear what this thread is about so why are you even here?

- it's obviously not boring/time-wasting for the other participants here.

- who are you to decide what I should or should not be interested and spend my time on?

.... your post is a wind-up, right?

To be sensible, the unit ‘H’ does not mean ‘hour’. An hour is ‘h’ - H is the Henry. Get it right.

The lagoon was clearly 700m long, rounded off to 2300ft by someone.

Don’t you just hate it when approximate values (metric or imperial) are converted to an exact value, to several significant figures, in the other system. Idiots doing the conversions. Probably mostly stupid journalists?

There are a lot of ‘idle uniteers’ around. Often they quote MW instead of MWh, so one has to guess whether they are referring to power or energy.

Beekeepers are the same. Few know what a ‘super’ is really. They have never learned any Latin, obviously.

Same with cells and batteries. Was there ever an anti-aircraft battery with only one gun? - no batteries are groups of more than one cell!

Apparently the americans missed Mars with a spacecraft, because someone didn’t use the correct conversion. I often use the wrong case on purpose, btw.

This argument is about units.

For some time there have been preferred standards for Metric units, and cms, although nuseful in certain circumstances are less preferred that mm and metres.

But at the end the argument is about what unit should be used.

That depends on the size of the feature being measured.

Unless you like LOTS of Zeroes before or after the decimal point, you would not quote the distance between Earth and the Sun in microns, any more than the clearance between a shaft and the bearing in which it runs in light years!

Clamping two large items together I might use M12 x 1.75, but if I wanted a fine adjustment more likely 1/2" UNEF or even ME 40.

Imperial Micrometers use 40 tpoi thread beacsue it is better suited to task inn hand than a M12 x 1.75 thread.

You will have a job refurbishing a 1910 Drummond using Metric hardware, just as if you tried to rebuild a damaged 2018 car using BSW hardware.

The unit has to be suitable for the task in hand, in the same way as the tool or machine being used.

No point bin going to war over which breed of horse to enter in the Grand national or for ploughing. Each type is ideal for a particular purpose.

There must be more important things with which to occupy our time

Howard

Metric is the rightful heir to the throne and already used in every progressive country and culture. Units of dimension are linked to volume, weights and indirectly temperature, and universally adopted by all the sciences. Based on decimals, the maths is a lot easier too. I work happily in imperial but once "our" generation dies out, the world will be metric rather than clinging to archaic and arbitrary measurements based (allegedly) on nothing more than the length between a 16th century monarch's finger tip and his nose. It's a done deal so don't shoot the messenger. As a bit of interesting trivia, an English bishop, John Wilkins, (1614-1672) invented the concept of a universal integrated measuring system that was the foundation of the metric system. The only people keeping imperial alive is the model engineer.

Oh no not yet another pointless thread on Imperial v Metric Measures

Tony

And that little thing called back compatability.

regards Martin

.

Like making DIL chips and boards with 2.54mm pitch

ferinstance

MichaelG.

Count your blessings chaps.

Having three systems of measurement gives me a cast iron (well, chrome vanadium actually) reason why I have to have THREE sets of shiny new spanners. Three sets gotta be more fun than just one, eh?

edit for minor typo

Edited By Simon Williams 3 on 09/04/2022 20:10:03

I don't think We missed Mars, just center punched it a bit.

Martin, Imperial measurements and hardware are not the sole province of the model engineer.

Preservationists in Railway, Traction Engines, Road Vehicles, and Industrial Archeology need Imperial measurements and hardware.

Indeed there may well be some machines in industry which still produce precise work despite containing "Archaic" fasteners and dimensions.

For a given situation, each system has advantages over the other.

As in everything, the horse has to be suitable for the course.

Howard

Wow! Look what I've achieved, ha, ha. Less than 24 hours and nearly 3 pages of arguments. Imp/Metric is like religion and a few other subjects that just run and run.

Having taken the P , I can say that I try to use what I'm given. Almost finished building Harold Hall's grinding jig for which the drawings were in metric. I enjoyed the journey as metric is so easy to use due to its decimal base rather than the medieval duo-decimal rubbish. If I am confronted with Imperial drawings, that's OK in that I was taught that at school to start with and metric later. Result is I can still visualise Imperial measurements that come so naturally from schooldays. Still prefer to multiply or divide in 10ths, metric. HH is one of the better model engineering designers who got it right whereas some have made drawing errors all over the place. Just one problem - sourcing small quantities of his specified material sizes. If necessary I can easily convert small dimensions from one system to the other, just using the calculator between my ears, not difficult. E.g., 19mm to .748", done in head. Real calculator says .7480314" I picked 19mm as a purely random size to convert. Obviously, I would much rather use one or other rather than flitting to and fro with the risk of errors.

My original points were that different milk suppliers placed emphasis on one or other system, no consistency. Conversions looked odd but admittedly I didn't think about American versions being slightly different. The other point about Chains or for that matter, Cables, Fathoms and lots of other ancient measurements really should be scrapped.

Reading through this thread I have noticed a number of mistakes which are probably typos but if they were to reach the shop floor they would result in some unexpected products. Maybe it highlights the problems of converting between systems.

Mike

< pedant alert >

‘Metric’ and ‘Decimal’ are not the same thing.

MichaelG.

Could be that people are unable to do basic arithmetic?

Andrew

Like NASA? They managed to crash a spacecraft by mixing units oops. I'm old and bi-lingual , but metric is best

Mike Poole,

That's precisely why I said that I try to use what I'm given, e.g., HH supplied his tool grinding jig drawings in metric in his book. So I used metric. Could only source some steel sections in Impreial, so I treated them as peculiar sized metric so all was in same system!

Andrew,

Basic arithmetic is my specialty, I think! In the example that I gave, 19mm, double it and again, so we have .760" I find it much easier for head calcs., to do it rather unconventionally, like next stage is having got to .760" on the assumption that 1mm = 40 thou, it's necessary to correct the 'error' being the difference between .039375 and .040000, which is 5/8 per mm , so 5 X 19 = 95, ÷ 8 = very nearly 12(thou) to deduct from .760" = .748", answer damn close to correct figure. Told you it's very unconvential and spelling it out above in minute detail seems long winded but I get there very quickly and it works very well.

Michael Gilligan,

I accept your comment but point is, multiplying/dividing by ten to calculate metric quantities is easy but impossible to match in Imperial, which is what I meant.

Duncan,

I know about the yanks balls-up. That's why I try hard to use what I'm given, be it Imperial drawing or a metric one. Rules and Verniers have both systems side by side so not difficult.

The cable is one tenth of a nautical mile so should be decimal enough for most people. The nautical mile is one of the few units that has a sensible derivation,it’s the length of a minute of latitude plotted on a standard navigational chart so distances can be measured with the simplest equipment,dividers. Not so with kilometres.

Fathoms haven’t been used here for many years but are still in use in the USA. If you want to tell the Americans they’ve got to stop using all these archaic units,good luck! Wars have been started over less.

I was thinking more of equating 30mm with 1 foot, an order of magnitude out.

For the example given I happen to know that 19.05mm is exactly 0.75", so just subtract 2 thou. Depending upon what I am doing I tend to work in imperial or metric, so rarely need to convert, at least to any degree of accuracy. If I do, it is done beforehand in the planning stage and written on the drawing.

Andrew