Metric vs Imperial – Practical or Traditional?

[John Stevenson 1Participant @johnstevenson1]

Because engineering has evolved thru time and standards we will always have these differing measures.

 

Just learn to live with whatever suits.

 

If the whole world changed this week to metric non of this would go away as the old machinery / goods / equipment would still be around.

 

For a nearly complete change to take effect would require all countries to change and a time span of many decades.

You know it’s not going to happen so why get upset over it.

 

Use what you prefer and can get on with.

 

John S.

[DMBParticipant @dmb]

Hi All,

I have a cork notice board in my workshop weith various notes drawing-pinned on, mainly laminated to keep `em clean.

Possibly of interest in the metric/imp section is something I cribbed from I cannot remember where;-

3 Horizontal lines, the first marked “inches” and reads left to right, .39  .79  1.18  1.57  1.97  2.36  2.76  3.15  3.54  3.94  4.33  4.72

Second line; 1  2  3    4 consecutively to 12

Third line reads “cm” (centimetres) 2.54  5.08  7.62  10.16  12.70  15.24  17.78  20.32 

22.86  25.40  27.94  30.48

Obviously, in the vertical, the .39 is directly above “1” in next lower line and in turn, directly above “2.54” in the bottom line.

Suppose you want to know what 6cm is, in inches. Look @ “6” in middle row and read

up to top row = 2.36 inches.

What`s 8″ in metric? Look @ “8” in middle row again and read down to bottom row =

23.32cm/203.2mm

How easy is this.

[DMBParticipant @dmb]

Hi All,

Having said what I have in last post, I try to keep to one or other system as required by what`s offered on drawing/in book, rather than constantly trying to convert.

I think the hardest work on say, loco-building, is coping with a drawing which says 16G

brass sheet in stock is 1/16″ and the angle to join it is say, 2mm thick. To find length of screw/rivet needed to join them, I would reduce everything to decimal parts of an inch.

John.  

[TerrydParticipant @terryd72465]

Posted by John Stevenson on 01/12/2010 09:40:43:

Because engineering has evolved thru time and standards we will always have these differing measures.

 

Just learn to live with whatever suits.

 

If the whole world changed this week to metric non of this would go away as the old machinery / goods / equipment would still be around.

 

John S.

 

Hi John,

 

Wikipedia quotes the CIA world handbook

 

“According to the CIA (World)  Factbook only Burma (Myanmar), Liberia, and the United States have yet to adopt the International System of Units as their official system of measurement.  However, they all have adopted metric measures to some degree through international trade and standardisation.  The United States mandated the acceptance of the metric system in 1866 for commercial and legal proceedings, without displacing their customary units.   Both Liberia and Myanmar are substantially metric countries, trading internationally in metric units. Visitors also report that they use metric units for many things internally with exceptions such as old petrol pumps in Myanmar, calibrated in British Imperial gallons.”

 

So we are in line with Myanmar eh, that makes me feel better about myself.

 

Regards

 

Terry

[Dinosaur EngineerParticipant @dinosaurengineer]

There is no one system that provides all the answers or satisfies all the needs .Engineers will always find another solution ( system ) if one system doesn’t offer what they want. Until such time that the metric system satisfies ALL needs, engineers will always find something else to do the job.

For the model engineer , the prices and availabilty in small quantities of minature metric screws ( incl. taps / dies etc) is a real problem . Also  metric scale hex sizes are not available. Is it it any wonder that we use B.A. threads / fasteners ( some times with non std. heads) ?

[TerrydParticipant @terryd72465]

Hi Dinosaur Engineer,

 

Model engineers will use what system they can, but only while it is available.  Systems have come and gone and probably always mourned by the diehards.  My old mum still tried to convert decimal prices to £sd while she was alive and she was only 40 when it was introduced.  She probably used the decimal currency for more years than the old.  When measures were standardised there were complaints that they would be unworkable because people could no longer use their arm or finger for measuring I expect.

 

metric scale hex sizes certainly are available, I buy them regularly at exhibitions, I actually find it more difficult to buy BA sizes locally and have to go to a very old fashioned hardware store 10 miles away to get them.  I’m not sure how long the shop can last as he is quite expensive. 

 

I must admit that anything smaller than 3mm has to be bought on the internet but I don’t find them more expensive than BA etc. In fact I think that imperial fasteners are becoming more expensive than metric as the latter are used worldwide now, even by NASA (albeit to their own spec) but the need for BA is quite a specialised market.

 

Terry

Edited By Terryd on 06/12/2010 17:04:50

[Dinosaur EngineerParticipant @dinosaurengineer]

Hi ! Terry,

I’ve found that as soon as I get below M1.6  the price rises exponentially and trying to get  high tensile grade 8 or better, difficult.

The BA stockist you mention must be the same expensive shop I go to !

[TerrydParticipant @terryd72465]

Hi Dino,

 

(Hope you don’t mind the shortening but my typing gets tired at this time of night). I’d certainly agree with you on the very small sizes but there are suppliers on the continent who will post to the UK and seem to be cheaper than here.

 

I think that hex head screws and bolts are very specialised and in quite small production runs.  Most very small stuff seems to be cross or torx heads.  I just think that we have to grit our teeth and bear it like it or not.  Actually I just looked at the Bruce Engineering catalogue on the Polly site and m1.2 (about 13BA)  set screws x 12 mm long are quoted as around 15p each for scale hex head rolled thread screws.  I didn’t think that too bad.   But they’re not ht.  The French supplier mentioned in another thread seem to have a good range of high spec screws at reasonable prices.

 

Terry

[James FairParticipant @jamesfair36731]

Ah, this is such fun! It’s been going on for ages. If any care to look, there is an entry in the Book of Second Chronicles regarding Solomon’s temple: “…the length in cubits by the former measurement being sixty cubits…”. They had an old cubit of 20.4 inches (518.16mm) and a new cubit of 18 inches (457.2mm). Solomon, famous for his wisdom, stuck with the former measurement. He could not have foreseen inches and millimetres, but he built an awesome structure according to plans set down in writing by his father, King David. So, someday metres and feet may give way to some other system. And this debate will carry on.

[TerrydParticipant @terryd72465]

 Hi James,

 

So Solomon must have chosen between the Sumerian cubit (30 Digits 20.4″) and the Greek Cubit (24, digits 463.1) which was used in ancient Greece in the 8thC BC.  He must have been an old man as he was supposedly around in the 10thC BC.  The only other cubit around in that century was the Egyptian Royal cubit (28 Digits or 20.64″ or 525 MM) he probably rejected the latter as it could vary by 3mm.  Note there are more digits in the Sumerian even though it is longer.  They must have had smaller digits.

 

Mind you, if he had been around much later he would have been spoiled for choice with at least 17 different cubits around. But we’ll probably not know for sure as no one has found any real evidence of a temple – yet.  Then we have the Ell, but let’s not go there. 

 

As to metres and feet, the success of the metre is mostly due to the fact that there is a standard decided internationally and that standard recognised worldwide.  In an era of international trade and manufacture that is essential.  Much like the standardisation of time zones in the UK when the railways arrived (much to the chagrin of the Bristolians London time was chosen).  Unfortunately the foot, like the cubit never had an international standard. Britain, as usual decided theirs was superior and the others could lump it or like it.  Most lumped it and chose the metre.

 

However us modellers don’t have to satisfy international standards and we can choose our own standards (at least as long as suppliers allow) be that the metre, foot, ell, cubit or barleycorn.  So just get on and enjoy modelling whatever you choose.  Good debate though, there’s a lot of interesting stuff to learn.  Knowledge is never wasted. As the saying goes,”a mind is like a parachute,  most efficient when open”.

 

Best regards,

 

Terry

[Nicholas FarrParticipant @nicholasfarr14254]

Hi,

 

            Posted by Terryd 07/12/2010 15:03:35

     Good debate though, there’s a lot of interesting stuff to learn.  Knowledge is never wasted. As the saying goes,”a mind is like a parachute,  most efficient when open”.

 

                  Every day is a school day.

 

Regards Nick.

      

[Sub MandrelParticipant @submandrel]

When one stops learning, one is dead.

 

Neil

[larry PhelanParticipant @larryphelan54019]

It,s not just Europe,the whole world uses Metric,except for a few oddball places.

The other system died with the "Empire",it just has not been buried yet. !

[Brian HParticipant @brianh50089]

I don't think it's very helpful to be an 'Imperialist' or a 'metricist', I use whatever is most useful although tend to go with Imperial because ;

a) I'm used to it and the majority of my equipment is Imperial.

b) I model old engines that were built to the Imperial standard and that makes it easy to work to 1/8, 1/6 or 1/4 inches to the foot.t

There are occasions when a metric hole or thread fits where another size does not.

Brian

[Mick B1Participant @mickb1]

Posted by Brian Hutchings on 25/08/2017 18:26:10:

I don't think it's very helpful to be an 'Imperialist' or a 'metricist', I use whatever is most useful …

…

Brian

Agree completely. My machine is metric, and there is a sensible range of small metric coarse threads which are suitable in the majority of cases. But there are some useful fine Imperial threads for which taps and dies are far more easily available than metric fine, and for that reason it sometimes makes sense to use them.

I'm fond of both – there's no sense in being a zealot.

One thing I do do when drawing – I denote the decimal point with a dot in Imperial, and a comma in metric, as I was required to do when I worked in a drawing office that used both – and if I use a dimension from the 'other' system in a drawing done in one, I'll put it in brackets with the unit alongside the dimension in the primary system, so that it's clear.

 

Edited By Mick B1 on 25/08/2017 19:18:37

[Enough!Participant @enough]

Posted by larry Phelan on 25/08/2017 17:27:29:

It,s not just Europe,the whole world uses Metric,except for a few oddball places.

Define "the whole world". The US certainly doesn't and doesn't pretend to. Canada does pretend to – i.e. it's nominally metric – but the de-facto working system in Engineering is Imperial. Even in supermarkets it's no better than 50/50.

So maybe "the whole world except for a sizeable chunk"?

[HopperParticipant @hopper]

Posted by Bandersnatch on 25/08/2017 23:09:24:

Posted by larry Phelan on 25/08/2017 17:27:29:

It,s not just Europe,the whole world uses Metric,except for a few oddball places.

Define "the whole world". The US certainly doesn't and doesn't pretend to. Canada does pretend to – i.e. it's nominally metric – but the de-facto working system in Engineering is Imperial. Even in supermarkets it's no better than 50/50.

So maybe "the whole world except for a sizeable chunk"?

But the US does use metric officially, it's just that they also use "customary measure" as well, making it one of those few oddball places in the quoted post.

[Ian S CParticipant @iansc]

You won't be metric until you go into the pub and order a litre of beer, instead of a pint.

My prefered tread system is UNF/C, I find that I like to use 1/8" W over 3 mm, but thats the only Whitworth size I use.

Ian S C

[HOWARDTParticipant @howardt]

is the beer English or American, if American you were sold short !!

[SamsarandaParticipant @samsaranda]

I think I remember reading somewhere that America (I.e. USA) was the first country to officially adopt the metre standard and that was in the 1870's or 1880's; suffice to say their progress towards full metrification has been a little slow!!!

Dave

[MeunierParticipant @meunier]

Posted by Mick B1 on 25/08/2017 19:09:48:

One thing I do do when drawing – I denote the decimal point with a dot in Imperial, and a comma in metric, as I was required to do when I worked in a drawing office that used both..

Edited By Mick B1 on 25/08/2017 19:18:37

Same system applies when writing out a cheque in France,
e.g one thousand two hundred thirty-four euros and fifty-six centimes
would be written in UK as 1(comma)234(dot)56 but in France is written as 1(dot)234(comma)56
DaveD

[Andrew TinsleyParticipant @andrewtinsley63637]

I was raised on both metric and imperial units. I don't have any preference for either system. If I am building a published design, then I use whatever system has been specified.

I have been able to get a lot of imperial tooling at relatively knock down prices, so I tend to use this system on most things I do. I also have a goodish range of metric tooling, so sometimes use this if the fancy takes me. It really is a totally non issue. Those that have been raised on metric measurement, let them use it, same goes for the users of the imperial system.

The one thing I will not do is to mix the two systems. I still find that nuts and bolts are readily available in Imperial sizes as is raw material, so if someone is kitted out with Imperial tooling, then what the hell does it matter if it is used? It really is up to the individual to do what he wants, that is the beauty of the hobby!

To read some of the answers given, it seems as if war has broken out. Get a life and do the engineering in whatever units you want!

Andrew.

[Philip DParticipant @philipd]

Posted by Terryd on 06/12/2010 21:58:40:

Hi Dino,

 

(Hope you don't mind the shortening but my typing gets tired at this time of night). I'd certainly agree with you on the very small sizes but there are suppliers on the continent who will post to the UK and seem to be cheaper than here.

 

I think that hex head screws and bolts are very specialised and in quite small production runs. Most very small stuff seems to be cross or torx heads. I just think that we have to grit our teeth and bear it like it or not. Actually I just looked at the Bruce Engineering catalogue on the Polly site and m1.2 (about 13BA) set screws x 12 mm long are quoted as around 15p each for scale hex head rolled thread screws. I didn't think that too bad. But they're not ht. The French supplier mentioned in another thread seem to have a good range of high spec screws at reasonable prices.

 

Terry

Which French supplier as i can't find anything by searching the forum ??

[Author]

Posts