Metric vs Imperial – Practical or Traditional?

[Sam StonesParticipant @samstones42903]

I’m not sure where this came from, or if it even fits into this Metric versus Imperial posting, but I was told a story about a really old toolmaker.

He was heard muttering words along the lines of :-

“I don’t why you lot bother with all these plus and minus tolerance things. When I was a lad, we used to get it right!”

Sam

[TerrydParticipant @terryd72465]

Posted by its-smee on 17/08/2009 08:38:00:

 

Some talk of millimeters and some of kilogrammes,
and some of decilitres to measure beer and drams,
but I’m a british workman,too old to go to school,
so by pounds i’ll eat,and by quarts I’ll drink,and
I’ll work by my three-foot rule
                                ( Rankine 1874 )

 Rankine said this because this as this was the date that the British government decided to adopt metrication because of the superiority of the system.  However several wars got in the way and the decision was not implemented until the 1960’s. 

 

The arguments rather remind me of the argument against metrication by the Tory MP who said that the kilogramme was too heavy for British housewives to carry!

 

By the way, as a matter of interest, the Florin (2 shilling piece – 10 p piece) was introduced in the 1840s as the first step in decimalisation of our currency.  Of course British inertia won the day and we still suffer from the mixed up ancient continental/French, old system of pounds and ounces and pounds sterling ( i.e. Livres in French – hence the modified L or £ for our pound and lbs for pounds weight,)

 

Try dividing inches by 5 instead of 3 and you’ll also see a problem.

 

Regards

 

[Anonymous]

Not only that but the US and English inches were different until the late 1950s.

 

Regards,

 

Andrew

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, I have no problem using imperial or metric, I use them both. This argument has and will rage on and on. What if some clever dick finds a more effective and efficient unit in the future, will we stick in the mud for metrication. Imperial units don’t aways suit everything, niether does Metric. Standards are certainly efficient, but do they always need to all be the same. Imagine if people were all conceved by the same efficient standed, well! you might not know who is you or me. Just a thought.

Regards Nick.

[DMBParticipant @dmb]

Hi all,

Here we are again, arguing about Imp/Metric. Metric has a number of very useful benefits, like multiplying/dividing can easily be done by shifting the decimal point in head or on paper, no need for a calculator. Just try doing similar calcs. with thous-a thousand to the inch then we go to 12 inches to the foot, 3 feet in a yard, a cock-eyed 1760 yards to a mile. Now add in all the other daft  measurements, many still being used , like chains (22 yards?) used by our Railways. Have you forgotten Rods, Poles, Perches, Gills, Ounces, Pounds, Hundredweights and Pennyweights, Quarters and Tons, Nautical Miles, Fathoms, 4 Quarts to 1 Pint, 8 Pints to a Gallon and so the rubbish goes on and on.

BTW, I am British, schooled in England and taught both systmes at school.

In a nutshell. the problem is either one of being to VISUALISE how far is a Kilometre rather than half a mile or thous against tenths or hundredths of a millimetre or half a litre versus a pint or old codgers RESISTANCE to change.

 

THIS IS HOW I GET AROUND THE PROBLEM

 

Iam building a loco to Imperial dimensions so I use the Imperial edge of my steel rule and my Imperail mike, electronic calipers set to Imperial measurements.

Suppose I need to know how long a screw or rivet is needed to fix together say running board to valance angle and one piece of metal is in Imp. and the other in Metric. Ju st measure thickness of both in same units then calculate length of rivet/screw in same units. I dont have a problem with something like that. 

[DMBParticipant @dmb]

Hullo Terryd,

Just read your post about the origins of our currency. I think you may be wrong. As I understand it, Pounds, Shillings and Pence or L, s, d, came from the Romans and Latin words, Libra, Solidus and Denarius. Still alousy method of measuring value.

John 

[John OlsenParticipant @johnolsen79199]

The Libra refers to weight, a British pound sterling was once a pound of silver. Presumably sterling silver, which is about 97% pure. Good luck with getting a pound weight of silver for a quid now. I do have a lump of pure (chemically deposited) silver here, weighs about 200 grams. Also a half a tin of silver fuse wire that someone painstakingly salvaged from a whole lot of HRC fuses. Ahh well, we are not broke yet.

 

regards

John

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, imagine 10 students sent out for four Pizza’s (because thats all they could afford) now for arguments sake all the Pizza’s were the same size and flavour and all the students expected an equal share. Dividing up four into ten in metric equals 0.4. Hmmm, 0.4 of a Pizza! not easy to cut with any consistant accuracy, a lot of squabbing ensues. However take an imperial view to the situation and the result to the problem is easy, cut all four Pizza’s into 1/3 rds and then cut two of the 1/3 rds into 1/5 ths, each student then gets 1/3 rd and 1/15 th of a Pizza. 1/3 rd plus 1/15 th as a decemal equals 0.3999999999 or as near as you can get to 0.4 of a Pizza. A practical use for imperial mearsurement. QED.

Regards Nick.

Edited By Nicholas Farr on 06/10/2010 11:37:42

Edited By Nicholas Farr on 06/10/2010 11:42:05

[David Clark 13Participant @davidclark13]

Hi There

What if it is a metric Pizza?

Surely you can have 1/3rd or 1/5th of a metric dimension?

1/3rd and 1/5th are not exclusivley imperial.

regards David

 

[Nicholas FarrParticipant @nicholasfarr14254]

Hi David, maybe so, but fractions were around long before metrication and before the digit 0 I believe. Without the 0 metrication would be dfficult, would it not?.

Regards Nick.

[MikeParticipant @mike89748]

Metric and imperial measurements are both man-made, so I (somewhat tongue-in-cheek) propose an entirely new system, based on nature. It would be divisions of the Nautical Mile (one minute of one degree, measured from the centre of the earth). Thus, one standard would suit all disciplines, from engineering to navigation…

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Mike, is not measuring as we percieve it, in itself man-made whatever unit you use? Nature has a habit of producing things in random sizes and shapes of its basic form of things, does it not?

Regards Nick.

Edited By Nicholas Farr on 06/10/2010 12:51:54

Edited By Nicholas Farr on 06/10/2010 12:53:52

[MikeParticipant @mike89748]

Hi Nicholas: I suppose you are right, so there goes another fine theory! And I wanted a measurement called the Mike – not out of personal vanity, you understand, but because the smallest increments would only be measurable with a micrometer…

[KWILParticipant @kwil]

Nick says that nature has a habit of producing things of varying sizes, perhaps its back to nature with cubits and feet?

[oilcanParticipant @oilcan]

if students are anything like the ones i come across in Liverpool you’ll end up with 4 very stuffed students and 6 hungry ones. but getting back on topic, i’m ambivalent about which is the best system . I hate trying to read 0.5mm graduations on a steel rule as much as I hate the 1/32nds. The one down side of imperial, as far as model engineering goes, is converting fractions from a drawing into decimal places. now for a question, did/does anybody make dial indicators and/or calipers that measured in fractions?

when i built the micrometer scribing block from Tubal Cains ‘simple workshop devices’-superb book by the way. very much aimed at the model maker- I used a 32 thread instead of the stated 40 TPI . purely because I could then scribe of in fractions instead of converting to decimal. it did make marking out a bit easier.

[Gordon WParticipant @gordonw]

The metre was originally measured as a distance on the earths surface subtended by some angle or other. We’ve had all this before deja-vu all over again. Things are the size they are, Whatever they are measured in.

[KWILParticipant @kwil]

Yes http://www.theToolwarehouse.net in USA does a caliper with, imperial, metric AND Fractions!

[Dinosaur EngineerParticipant @dinosaurengineer]

I don’t understand why some people find it difficult to work with both systems . Today we have computers and calculators that will instantly convert from one system to the other to the umpteenth decimal point. I remember having to use 7 figure log tables in the toolroom to work out some conversions and trig calcs. We even had a 500 inch rotary slide rule ( Fowlers ?) in the jig & tool D.O. for the non-critical sizes/dims/calcs.

Today it’s so easy !

 It’s just as easy to turn something accurately to 1.000 inch or to 25.4mm or conversely to 0.984 ” or to 25mm if you have the correct measuring gear.

The main problem I see is the reducing availabilty of imperial stocks of materials. 

As more designs are done in CAD , then it becomes much easier to see the effects of changing material sizes, from one system to the other, to the overall design and work out the compensating changes required. To this end it would help if designers published clear layout / assembly drgs. ( ideally in CAD) to save having to wade through lots of detail part drgs.

[chris stephensParticipant @chrisstephens63393]

Hi Oilcan,.

Yes, they do make them, I have two different ones. No let me correct that, I HAD two, one a Swiss made dial caliper, now sadly broken. The other a digital one, I think from Warco, has been “borrowed” by the workshop Gremlins, it was there one minute and gone the next. This is a shame because it was my favourite caliper, it had auto ON as well as auto OFF. Must buy another one at the Midlands, if for no other reason than to encourage the pesky little blighters to return the first one. Has anybody else found that this tactic works on them? 

 

On the other issue, I agree the ONLY problem (for our usage), apart from prejudice, with Imp is the use of fractions instead of decimals. A Thou is a much more friendly unit to work to than a 0.01mm. Who really wants to work to two and a half of any units, (the Metric equivalent.)?

 chriStephens

 

 

[Raymond AndersonParticipant @raymondanderson34407]

attn niloch,

                        Being a bricklayer to trade I feel I can jump in here re brick and block sizes,

All standard bricks and blocks are in metric sizes  you can still get imperial sized bricks but they are regarded as specials  if you ever have to match in metric blocks into an existing imperial block wall you can look forward to having mortar beds that you could sleep in.

                                                          Regards 

[Ian AbbottParticipant @ianabbott31222]

For a lot of jobs, I use the spray paint method.  Hold the pattern up against the material, a quick spray over with mat black paint, when dry, cut around the line with a big saw / chisel / hot axe, job done.

 

And when I wor a boy, it wor uphill both ways, barefoot, three feet o’ snow, in the dark. 

 

Ian 

[adyParticipant @ady]

I prefer the Mayan base 19 system.

 

It’s far more accurate for those big jobs.

[John OlsenParticipant @johnolsen79199]

Actually we should toss all the measurements and change the way we count to base 12 instead of base 10.

 

As well as the modern digital calipers that do fractions there were  Vernier calipers that had them as well. I have an 6″ Mitutoyo one, must be nearing its 40th birthday by now. It has Inches by thous on one side, and inches by fractions on the other. The calibrations are in sixteenths. The Vernier for that side has 8 divisions over 7 sixteenths of an inch, so it reads down to 1/128″. Not that the fractional side has ever proved to be very useful.

 

One thing that I hate about the older designs is having to add up all those strings of fractions with different denominators.

 

The difficulty with attempting to standardise is that the old standards never really go away.  So you end up having to deal with all of them. There are after all still people using Holtzapfel screw threads. The supposedly metric European countries use what look at first sight like some very unusual dimensions for plumbing threads, but they actually translate to British standard pipe. I started out with a metric Unimat 3, so bought metric drills and metric taps and dies, including some of the fine series ones which are actually quite nice…8mm by 0.75 for instance. But now my workshop is full of a mixture of metric and Imperial stuff, often on the same job. On my launch engine all the bought screws and nuts are metric, but anything screwcut like the glands and ends for the rods is Imperial. The material used is a mixture, sometimes you can buy inch  stock and sometimes you can buy 25mm. Oh well, at least it runs well. Good luck to anyone trying to fix it in 25 years time!

 

(The metric screw pitches are badly chosen from the point of view of screwcutting, an Imperial gearbox is much simpler than a metric one.)

 

regards

John

[oilcanParticipant @oilcan]

Thanks Kwil and Chris for the heads up re fractional calipers. Now i know what to look out for at the ME exhibition.

and Ian, just three feet of snow!!! shear luxury !!! 

[Sam StonesParticipant @samstones42903]

These days Nicholas, I prefer my Pizzas cut into four quarters. Six pieces is more than I can eat.

 

Or should I go for two pie radians?

 

In my tool box, I have a 1 to 2 micrometer which I hardly ever use. It came with my 2nd hand ML7.

 

On one side of the line it’s graduated in decimals, while on the other side it’s in eighths (I’m talking inches of course).

 

I mis-read it on an important job (only once) and, as a result, lost quite a valuable customer.

 

A lesson well learned!? 

 

Sam

Edited By Sam Stones on 07/10/2010 02:25:56

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