Metric vs Imperial – Practical or Traditional?

[John OlsenParticipant @johnolsen79199]

While the metre, kilogram and second are the base units in terms of which other units are defined, that does not mean that you are not allowed to use other units at all. The preferred style is to use multipliers that are powers of three (or multiples of three), hence kilometer (10^3) or millimetre (10^-3) and so on. But I don’t think that “preferred style” means that a policeman will grab your collar if you choose to use centimetres here and there.

 

The main drawback with metrics, and it applies to inches and thou too, is that pesky little decimal point, which can so easily disappear or get confused with a flyspot on the paper. Why can’t we have a more visible delineator? (There is also the fact that the continentals use the comma and the dismal point the opposite way around to what the rest of us do…)

 

regards

John

Edited By John Olsen on 04/11/2010 22:37:23

[VersabossParticipant @versaboss]

A lot could be said from a continental viewpoint to the above statements:

– it is not forbidden to use centimeters. A carpenter or a mason – afaik – does not work in mm.

– the correct dividers/multipliers are: milli = 1/1000; centi = 1/100; deci = 1/10; deca = 10; hecto = 100, kilo = 1000. A centigram would be 0.1 g or 100 mg. In Austria it is very common to use dekagrams (e.g. in recipes)

– The comma as decimal point is used in Germany for currency values, e.g. 3,90 Euro; but not in engineering (measuring) contexts. In my country we use always the point.

The REAL difficulty – as seen from here – is that it is not possible (here) to obtain material in imperial dimensins. So using 3 mm steel instead of 1/8″ leads to much arithmetic(and errors)  in changing dependent dimensions. 

And, btw, I think this theme is now fully  beaten to death…

Greetings, Hansrudolf

[chris stephensParticipant @chrisstephens63393]

And thanks to Microsoft we can’t even put our decimal point in the right place, we have to use a full stop instead.

chriStephens

PS I did not mean that we can’t use suitable prefixes where necessary, it is just that the SI system , which is the system under which the ISO works, only recognizes the base unit Metre and no other. It is obvious that for convenience there are separate names for both larger and smaller divisions. It is much easier to say zero point zero zero zero zero zero oneM as Mu.

One problem we could overcome with the metric measurement scheme is the unfortunate fact that the smallest unit most of us work to in metric has no convenient name, unlike the IMP system which has a “thou”. I therefore propose that we, as model engineers, give a name to the smallest unit on a standard metric micrometer ie one hundredth of a millimetre, that name should I feel be a DaMu (pronounced Damn-you) which is made up from the symbol Da meaning 10 and Mu a millionth of a metre. 10 micron being a 1/100th of a mm. Sorry for using fractions but they do have their use even in metric. The only other name could be a “HUN” short for hundredth of a mm, but then ones significant other might think you were calling for a coffee, if spoken out loud.

Edited By chris stephens on 04/11/2010 23:20:30

[EddieParticipant @eddie]

Hi
The bottom line is the egg was laid.
Accept that one work in Units that they are comfortable with.
I use both.
Woodworking is still in Inch standards; Think a little about the odd sizes metric wise that wood working equipment and timber is sold in.
Depending on the plans at hand I switch between standards or convert to metric.
I still say; Personal preference prevail.

Eddie

[Howard JonesParticipant @howardjones35282]

I laid out my last piece of earthwork in cubits.

’cause it was easiest.

truely.

[KWILParticipant @kwil]

Chris, 21·52 looks like a decimal point to me in Microsoft Word as pasted

[chris stephensParticipant @chrisstephens63393]

Hi Kwil

I was thinking about the MS standard keyboard, which only produces full stops, even when using the numbers pad on the right. 

chriStephens 

[Howard JonesParticipant @howardjones35282]

in Kwil’s post above, highlight the decimal point, then place the cursor over the highlight

and right click the mouse. select ‘view selection source’ from the menu.

Kwil you’ve used a symbol font.  Chris’s point remains correct.

[Ian AbbottParticipant @ianabbott31222]

Some years ago in Canada, pre CAD, I had to translate the metric dimensions and redraw the plans of a new theatre, so that the occupiers could use all their Imperial drawing templates and equipment.

When I came across measurements of 5715 mm, my mind switched off until I realised that it was a nice even 225 ft.  I discovered as I went on, that the designers had drawn an Imperial theatre, because all of the materials were in feet and inches.  After it was all finished, they sat down with a calculator and changed all the measurements to millimetres and drew it at 50:1 instead of 1/4″, making the plans impossible to use with imperial lighting and scenery templates.  I swear that they had a copy in Imperial which they refused to give us.

 

And, on probably fifty percent of the odd jobs that I make parts for, I don’t use any measurements.  Turn a piece of metal to something that looks right, then bore a hole until it fits.

 

Ian 

[KWILParticipant @kwil]

Of course I used the symbol font just as I would if I were typing an article that requires a decimal point, merely showing that you can provide the decimal point if you need to. As Chris said he was refering to a standard keybord entry, which was not stated in his original as he subsequently informed us.

[Peter G. ShawParticipant @peterg-shaw75338]

Chris,

 

The following from Tubal Cain’s Model Engineer’s Handbook, with suitable abreviations:

 

“Both the ‘MKS’ (note the order of letters) and the ‘cgs’ systems have been abandoned in favour of SI.”

 

“The SI system is now universally adopted in science, and is almost so in engineering….”

 

“The ‘preferred’ prefixes are those which go up and down by 1000 at a time….  In length, therefore, the centimetre (1/100 metre) is not used in engineering practice and though it may be retained in domestic usage (eg in dress-making) it is best avoided even here.”

 

Just for the record, most of the time I use metric – SI units. If using these units, I will NOT use anything other than mm, m or Km, and if people are incapable of understanding it, then that’s their hard luck – they will have to learn, and learn quickly *. I do use imperial – if it happens to suit, eg when measuring a length, it may be that the imperial graduations line up whereas the metric ones don’t.

 

* I do realise just how this sounds, but having been on the receiving end of a salesman who quite obviously did not understand what he was talking about, and read reports of the crap, to be blunt, that some salesmen talk in an attempt to sound knowledgable, I now no longer care what these people think. Generally speaking it’s their loss when I walk out because they don’t know what they are doing.

 

On the other hand, those salesmen who do use correct terminology are the ones who will make the sale, even if they don’t understand it!

 

Regards,

 

Peter G. Shaw

 

 

 

[TerrydParticipant @terryd72465]

Hi Ian,

 

5715 mm = 18′ – 9″ not 225′ – 0″

 

QED

 

T

Edited By Terryd on 05/11/2010 21:27:53

[TerrydParticipant @terryd72465]

Hi Ian

 

P.S.

 

225 feet = 68.58 metres. 

 

Something wrong here!  I’d like to see that theatre.

 

T

[blowlampParticipant @blowlamp]

5715 mm = 225 inches.

 

Martin.

[TerrydParticipant @terryd72465]

225 inches = 118″ – 9″ as I said

 

5715mm does not equal 225 feet as Ian Stated!

 

It may be similar to Chris Stevens decimal point problem except someone mixed up feet and inches – could lead to interesting results.  But silly me mistakes aren’t likely in the Imperial system – are they?

 

QED

 

T

Edited By Terryd on 05/11/2010 22:04:15

[Sub MandrelParticipant @submandrel]

Don’t blame Microsoft for that one, its the ASCII standard’s fault!

 

Neil

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Terryd, I think you were right the first time.

 

Regards Nick.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi all, 13 pages a bakers dozen, seems this thread is imperial. (pun intended)

 

Regards Nick.

[blowlampParticipant @blowlamp]

Posted by Terryd on 05/11/2010 21:45:00:

225 inches = 118″ – 9″ as I said

 

5715mm does not equal 225 feet as Ian Stated!

 

QED

 

T

 

Edited By blowlamp on 05/11/2010 22:04:41

Edited By blowlamp on 05/11/2010 22:06:23

[blowlampParticipant @blowlamp]

I know that, but he obviously made the mistake of putting feet where he meant to put inches.

 A bit like the mistake you’ve just made

 

Martin.

Edited By blowlamp on 05/11/2010 22:15:21

[TerrydParticipant @terryd72465]

Which mistake did I make? Please elucidate

I believe that my calculations were correct!

 

5715mm = 18′ 9″ = 225 inches

 

225feet (Ian’s assertion) = 68.58 metres

 

Quelle probleme?   118 was a typo, QED it is very easy to add an extra digit, much more difficult to type feet instead of inches.  As I said – equivalent ot Chris Stevens decimal problem. see my slightly earlier post on the subject.

 

 

Edited By Terryd on 05/11/2010 22:22:47

Edited By Terryd on 05/11/2010 22:25:36

Edited By Terryd on 05/11/2010 22:26:42

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Terryd, look at your follow up posting. (second one)

 

Regards Nick

[adyParticipant @ady]

…oops…we just crashed into Mars…again.

 

Anyone want to build a satellite in cubits and palms? those guys have a good record of accuracy.

Edited By ady on 06/11/2010 00:47:03

[adyParticipant @ady]

I think we’re missing the essential ingredient for accurate measurements, proper working practices.

The great pyramid is still the most accurate structure ever built because the builders were motivated to get it right.

 

If you got it wrong then your eyes were gouged out and you were disembowelled in front of your work colleagues.

 

NASA should learn from this.

[paultParticipant @pault16755]

Sorry I don’t see the problem. When I was an apprentice we had a mix of imperial and metric machines and drawings, and that is still true for me today. You just got on with it whatever combination of machines and drawings you had. It’s not hard to convert so work in whatever you are happiest in. At the end of the day there is no right or wrong answer, it is purely a question of personal choice.>>

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