# Trying out metric



## potman

So, if I'm going to make an engine I'm going to need a shop.
If I'm going to have a shop I'm going to need a workbench.

Went to the store today and got materials for a workbench.
Saw a tape measure with a metric scale.
Thought I might as well start getting used to metric measurements.

WOW, this is cool.

Instead of 27 5/8 + 3 1/2 - 3/16 = ???
Paper and pencil time.
But 70.2 + 8.9 - 0.5 = 78.6
I can do that in my head.

However,,,
Just how long is 61cm?
How high to my waist, in cm?
I dunno ???

Gotta measure everything now.
No intuition at all.
This must be what it's like to be a young child.

earl...


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## chillybilly

join the mixed up mayhem!!!!!!!!!!! " 8'x4' of 12mm plywood please " :big:


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## websterz

potman  said:
			
		

> So, if I'm going to make an engine I'm going to need a shop.
> If I'm going to have a shop I'm going to need a workbench.
> 
> Went to the store today and got materials for a workbench.
> Saw a tape measure with a metric scale.
> Thought I might as well start getting used to metric measurements.
> 
> WOW, this is cool.
> 
> Instead of 27 5/8 + 3 1/2 - 3/16 = ???
> Paper and pencil time.
> But 70.2 + 8.9 - 0.5 = 78.6
> I can do that in my head.
> 
> However,,,
> Just how long is 61cm?
> How high to my waist, in cm?
> I dunno ???
> 
> Gotta measure everything now.
> No intuition at all.
> This must be what it's like to be a young child.
> 
> earl...



A couple of quick rules of thumb...

Roughly 2.5 centimeters to the inch (2.54 but 2 1/2's close enough for raw stock)
1 meter = 39 inches (again, a close enough)

And the golden number  0.03937 for converting millimeters to Imperial. 

10mm x .03037 = .393

3/8 (or .375) / .03937 = 9.52mm


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## bentprop

> " 8'x4' of 12mm plywood please "


And though the nominal size is 2400x1200,the actual size of the sheet is 2440x1220!
Luckily I was edumacated in Holland,which has always been metric 
Think yourself lucky you don't live in the times of Ell,Bushel,or pigs bladder :big:


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## zeeprogrammer

earl!

Where are you located? Could help us help.

Pics! Love to see pics of a workshop coming together.


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## mklotz

> Instead of 27 5/8 + 3 1/2 - 3/16 = Huh?
> Paper and pencil time.



10/16 + 8/16 - 3/16 = 15/16

Add 27+3 and you've got 30-15/16

Easy enough to do in your head.


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## Artie

Metric is a good thing IMO, I was in school when we changed so Ive a little grounding in both but predominately metric. Because Im so used to it, its definately my preference and having everything in tenths is much easier to head calculate, again, just my opinion.

However, when I was an apprentice mechanic, we still did the old buddy up with an experienced older guy and Vince was my man. Vince was a specialist at engine building so whenever our shop got such work it was Vince (and his '*****'... me..). Vince was 'old school' so I learnt engines in thou. And today everything in my world is metric, cept engine specs...

Works for me... 40 thou per mm... simple enough.....

Artie


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## Tin Falcon

I am with marv I used to work in a steel fab shop. The foreman was a very educated man, a dentist as a matter of fact ,but he used and needed a construction calculator to add fractions. I would do it in my head then check my numbers on paper well actually soap stone on steel. Doc just could not do it. 
Tin


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## GrahamC

I guess I have just been lucky. I grew up with imperial measurements and in school it was imperial except for science which was Metric. So, when Canada went Metric it was an easy matter for me. Besides, I have always had a head for numbers, add, subtract, multiply, divide - decimals or fractions doesn't make a difference. I surprise my wife when she can get me out grocery shopping - in a basket with 50 or so items I will tell within a dollar what the total will be when she checks out.

I like to mix measurements just to throw someone off like I will ask the guy at the parts counter for a dozen M6 socket head screws 1-1/2" long.

And when asked how far it is to someplace (say it's 160km), I will tell them it's about 2 hours.

cheers, Graham


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## ironman

Is that magic number .03037 or .03937? I just ate dinner and my brain isn't on the ball for thinking right now?


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## Deanofid

Metric? Have fun with it, Potman. 
It's just for folks who don't know their fractions, you know...
_(nudge, nudge, wink, wink.)_

Dean


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## websterz

ironman  said:
			
		

> Is that magic number .03037 or .03937? I just ate dinner and my brain isn't on the ball for thinking right now?



.03937


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## mklotz

[pedant]

Actually, the magic number is 25.4, exactly. The inch is *defined* as 25.4 mm. Yes, that's right, the inch is defined in terms of the metric system. (As are many of the other basic units in the Imperial idiocy.)

1/25.4 = 0.039370078... is an irrational number. That means that the decimal representation goes on forever whereas the 25.4 representation is exact since that's how the inch is defined.

[/pedant]

Clearly, if one is simply estimating, none of this matters - calling a millimeter forty thousandths is good enough. However, if using a calculator, it's less keying to divide by 25.4 than to multiply by 0.03937. Further, most people seem to have less difficulty remembering 25.4.


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## jimmyocharlie

i work in both metric and imperial!

i run CNC's, some are programed in metric and some imperial!

altering an offset to take thou off, is either 0.001 or 0.025! it can make it an interesting night when you are running one of each :big: :big: :big: :big:


wheights still catch me out though, in England its all metric, doing the shopping online i've bought a Kilo of mushrooms (thats a LOT!), pounds and ounces makes sense, but Kilos..............................


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## mklotz

> in England its all metric



Come again?

Pints of beer, stones on the bathroom scale, and, IIRC, miles on distance markers?

Do you still use that hundredweight (cwt) that weighs 112 pounds?


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## mu38&Bg#

CNC runs in both. Just set G20 or G21 Right? I like metric. Too bad it's hard to find good metric lathes in the US at a hobbyist price.


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## potman

Being ignorant about such things....
What makes a lathe "metric" ???

Is it just the gearing for the screw thread, and
the calibration on the handwheels?

Or is there more to it ?

earl...


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## Noitoen

potman  said:
			
		

> Is it just the gearing for the screw thread, and
> the calibration on the handwheels?
> 
> Or is there more to it ?
> 
> earl...



Isn't it enough? Working with fractions to me ......... :rant:


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## mu38&Bg#

Yes, metric leadscrews and dials on the ways and a metric threading lead screw. I work in inches while turning parts no problem, but threading is not so simple. I have to come up with some change gears. I do have a small CNC mill and just received a thread mill. I'm going to try thread milling in the mill.


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## Deanofid

mklotz  said:
			
		

> Do you still use that hundredweight (cwt) that weighs 112 pounds?



Talk about getting your moneys' worth. 'Course, that would make me even fatter than I already am..


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## rake60

Prints may be drawn with metric, imperial, or some measurement based on the
width of the current King of Mars thumbnail or how far a common garden slug
can travel in 15 seconds. It doesn't change a thing when it comes time to 
cut the metal. In any language a size is a size. You will either hit the size 
or miss it. If you miss it make the mating piece to fit. It really doesn't matter 
what the numbers on the paper are. They might me millimeters, they might be
1/16ths of an inch. If it fits together in the end and works, it is a successful
machining operation.

If you will excuse me now I need to go and recalibrate my adjustable Crescent
Wrench. It is Imperial of course and I need it to work on my Suzuki Tracker 
tomorrow. Converting it to metric may keep me up all night!  

Rick


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## Davo J

An easy way to get used to metric coming from imperial is to buy a metric/imperial tape, then you can easily convert from one to the other untill you get used to it.
Dave


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## ToniTD1490

From http://www.kanabco.com/vms/library.html

There are two systems of measurement used in machine shops today, the Metric system and the Inch system.
The Metric system is based on the meter as the standard unit of reference. A meter (approximately 39.37 inches in length) is subdivided into 10 equal parts called decimeters. Each decimeter is divided into 10 parts called centimeters and each centimeter is divided into 10 parts called millimeters.
The Metric system is a very coherent system because it is exclusively a decimal system and therefore has a common multiplier and divisor of 10. Regular fractions are not used in the metric system. Instead the metric system uses only decimal fractions. Other names for the Metric system include SI units and ISO units. The Metric system is the most commonly used system of measurement in the world.
The Inch system is based on the foot as the standard unit of reference. A foot is divided into 12 equal parts called inches. Each inch is subdivided into a variety of fractions and decimals.
The Inch System is a rather incoherent system because it lacks the decimal based advantage of the Metric System. Parts of a foot can not be easily expressed as decimal inches. For example, in the metric system 7 millimeters is 0.7 centimeters which is 0.07 decimeters which is 0.007 meters. But 7 inches is 0.583333 feet which is 0.19444 yards and so on. This is a clear advantage for the metric system.
Another name for the Inch System is the English System. The Inch System is used in most English speaking countries but is being slowly replaced by the metric system. I like Metric, because I learnt with the Metric System, but other people like Imperial.

Regards, 
ToniTD1490


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## tel

The beauty of the metric system is that it's just so darned logical (to paraphrase Samuel Clemens, speaking of the Ethan Allen pepperbox) one litre, is defined as a cube 100mm on all sides, and, by co-incidence, weights 1 kilogram


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## ToniTD1490

In 1901 liter was described as the volume occupied by a mass of 1 kg of pure water in its maximum density and to normal pressure (to 4 °C and 1 atm respectively). This definition was repealed in 1964 because the liter was differing from the cubic decimeter in approximately 28 parts for million, inducing to mistake in the measurements that need enough precision. Nowadays only It is used as a special name of the cubic decimeter.


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## tel

Hmm .... it's close enough for me, at any rate.


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## Maryak

mklotz  said:
			
		

> Do you still use that hundredweight (cwt) that weighs 112 pounds?



LENGTH

4 inches = 1 hand
12 inches = 1 foot
3 ft = 1 yard
5.5 yds = 1 rod pole or perch
4 poles = 1 chain
100 links = 1 chain
10 chains = 1 furlong
8 furlongs = 1 mile

WEIGHT

16 drams = 1 oz
16 ozs = 1 lb
14 lb = 1 stone
28 lbs = 1 qtr
4 qtrs = 1 cwt
20 cwt = 1 ton (long)

VOLUME

4 gills = 1 pint
2 pints = 1 quart
4 quarts = 1 gall (imp)
2 galls = 1 peck
4 pecks = 1 bushel
8 bushels = 1 qtr

These and many other wonderous ways of measuring things are all part of the rich tapestry of British ancestry.

Best Regards
Bob


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## tel

Yep, what's difficult about that? But you left out Rods and Perchs and other associated seafood Bob!


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## Maryak

tel  said:
			
		

> Yep, what's difficult about that? But you left out Rods and Perchs and other associated seafood Bob!



The pole = the rod, both of which equal a perch, (if your very patient and very lucky whilst dangling your rod or pole in the canal with a maggot and a bent pin on a piece of string).

Best Regards
Bob


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## mu38&Bg#

rake60  said:
			
		

> If you will excuse me now I need to go and recalibrate my adjustable Crescent
> Wrench. It is Imperial of course and I need it to work on my Suzuki Tracker
> tomorrow. Converting it to metric may keep me up all night!
> 
> Rick



You must have an old one. That standard went out a while ago. My craftsman adjustable wrench is both metric and imperial. I'm not kidding.


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## GWRdriver

With exception of repair of foreign-built models most of my work is in Imperial but I've learned to flit easily back and forth between the two systems by choosing to memorize .03937 and using that in transposing dimensions. That is also an exact number, derived from the inverse of 25.4. Most people seem to prefer the 25.4, and that's their choice, but for me the .03937 prooved to be more convenient and more intuitive. Either way, as someone said, it's simply a way to measure distance between two points. One thing that helped me get a better feel for length in metric was to buy a 12" (oops! 300mm) scale and keep it lying around on the on the bench for an occasional comparative measurement.


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## shred

Ah, it must be time for the annual Metric-Imperial fest again 

The only thing I dislike about metric, well SI, to be pedantic, besides not being able to get stock or cutters or much of anything else easily in it here, is they didn't do a lot of human factors work before deciding on the core units. Yeah, they're fractions or multiples of some universal constant (or are now), but there's a reason inches, feet, pounds and so on evolved over time to be the way they are (and pecks and ells and hogsheads fell by the wayside)-- in the core "units", they're a convenient physical size for the task at hand.


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## mklotz

Excellent point, Shred.

One of the best examples of this is the Pascal, one Newton per square meter. It equates to 0.000145 psi, way too small to be useful.

However, as always, people will rearrange the system to their own comfort. Now widely used, though not, I believe, endorsed by SI is the 'bar' or 10^5 Pascal, which is a useful size and, coincidentally, almost equivalent to one atmosphere.

Most of these derived units are, however, simply related to the primary units so conversion simplicity is retained - unlike the Imperial system where they would have probably defined it as 5280 Pascal or somesuch nonsense.

I don't why the SI attempts to suppress the intermediate units (e.g., cm, dm, cc, cg). There doesn't seem to me to be any advantage and much disadvantage. Include them and exercise control over the inevitable derived units to keep the system usable.


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## Maryak

mklotz  said:
			
		

> I don't why the SI attempts to suppress the intermediate units (e.g., cm, dm, cc, cg). There doesn't seem to me to be any advantage and much disadvantage. Include them and exercise control over the inevitable derived units to keep the system usable.



Don't worry Marv, 

I have a metric wife from a metric country and to measure anything cm is the only one used, e.g. 23 1/2 cm. I reckon it will never be suppressed as half the population refer to their dress, bust, waist, hip measurements etc. in cm.

We should be buying Newtons of potatoes but we buy by the kg; so if the boffins don't want their system misunderstood they need to go with the flow and as you say not impose unrealistic and sometimes meaningless terms/rules on an already confused transitional generation.

Best Regards
Bob


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## mklotz

Speaking of centimeters and the ladies...

The medical community still measures dilation of the birth canal in centimeters. Also, most syringes are calibrated in cubic centimeters. 

Yes, Newtons of potatoes. At least the French had the good sense to not use the same unit name for force and mass.

Whenever I'm forced to deal with the Imperial system, I wonder, "Could they have possibly made it any worse?" I suppose the answer is yes, but I'm hard-pressed to understand how.

The astounding thing about the Imperial system is that its staunchest advocates don't understand it either. That explains why the USA will never adopt metric. If they did, they would have two measurement systems they don't understand.


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## Noitoen

mm or cm here in Portugal, depends on the profession. Carpenters use cm, machinists use mm and when they talk "precision" they use 1/100th of a millimetre.


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## Loose nut

mklotz  said:
			
		

> The astounding thing about the Imperial system is that its staunchest advocates don't understand it either. That explains why the USA will never adopt metric.



Americans will not adopt the metric system because they don't want to, not because it might be a better system or it would put the whole world under a unified measurement system. The more they think that metric is being forced on them the more they resist, generally if they didn't invent it they don't want it. To some of them accepting the Metric system is tantamount to announcing the arrival of the anti-Christ.

As for making the whole world unified under one measurement system, why should we, nothing else in the world is unified, different language, religion, money, government types, calendars, standards for the same things, etc, etc, etc. 

The only way we can get the whole word onto one system is to throw out both the imperial and metric system and institute a new universal system that everyone will use, then we will all be the same, miserably unified.


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## zeeprogrammer

Loose nut  said:
			
		

> then we will all be the same, miserably unified.



 Rof} Rof}

I love it!


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## bucketboy

Loose nut  said:
			
		

> Americans will not adopt the metric system because they don't want to, not because it might be a better system or it would put the whole world under a unified measurement system. The more they think that metric is being forced on them the more they resist, generally if they didn't invent it they don't want it.



You already do use metric..............

How many cents in a dime and how many dimes in a dollar ;D

Bb


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## John S

Only the BBC and dressmakers use cm, every one else uses mm up to 1,000 then it's metres.

Fractions are Ok but in 60 odd years of being around machine tools i have never seen a dial in fractions.

In imperial you have two measurements 31/64" is equal to 0.4844. Possibly a drawing says 31/64" but you have to turn or mill to 0.4844, room for error there.

In metric that measurement is 12.304, period, full stop, end of story, no room for error.

John S.


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## John S

mklotz  said:
			
		

> [pedant]
> 
> Actually, the magic number is 25.4, exactly. The inch is *defined* as 25.4 mm. Yes, that's right, the inch is defined in terms of the metric system. (As are many of the other basic units in the Imperial idiocy.)
> 
> [/pedant]



Are you sure Marv ?









John S.


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## Artie

hi John, nice example...someone had a redface over that. Yes Marv is sure...25.4 is correct. I love that....


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## John S

Had another one but lost the pic.
It went 8", 9" 11" 10" 12"

Branded rule as well, not an import.

John S.


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## bucketboy

Just to add more confussion, I was in a pub quiz the other day, the question "how many pints in a Firkin"?


No one had a Firkin idea ???

Bb

72 by the way ;D


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## Blogwitch

John, you didn't highlight where that rule was made. So much for home grown US being better than everyone else's in the world.

As was stated before, this subject rears it's ugly head every few months, and the same arguments abound every time.

It all boils down to just one thing. Eventually the people of the US, the last major bastion of imperial measurement, will start to lose massive overseas sales because of the 'we are the greatest and everyone should follow us' attitude. Unfortunately, the trading world doesn't look at it the same as you as individuals do.

The world is changing, and the US are going thru what the UK went thru in the last century, when our 'Empire' started to break apart. Luckily, most of our splits were amiable, and can we still trade easily between each other.

Who you used to deal with are now forming together to have their own trading empires, mainly the far east and Europe, now very much larger than the US 'empire' is, and of course, those two are now trading very easily between themselves, using the metric system of measurement.

The attitude of 'this is what we use and you will have to take it or leave it' is not the way in this modern world. Your stubborness just might just force most of the other world traders to just leave it, and you will be isolated in the world of commerce.

There is a lot more than just debating what is the best for you to use, your debate should be, 'How will I cope when we have to go over to metrication', because no matter what you say here, in the next few years, the Imperial dinosaur will have to be sorted in the US, otherwise you will find yourselves getting even more isolated as a world producer. 
I think a lot of your manufacturing is already producing metric, but the general population also have to take hold of it as well, otherwise you will find that one will fight the other. Where are the manufacturers to get the workforce from if the kids are still taught imperial instead of metric? 
You might even find it appearing on your job interview. "Can you work in metric?" "No", "Then very sorry, we can't use you".

We had to do it in the UK, and the same sorts of arguments came out then from our side. It is only us diehard model engineers that still use imperial, because we have to, everywhere else uses metric.
It took a long time to get fully assimilated, but now we have 'gone' over, we are back in the fold, and stand a much better chance on the manufacturing side when the world starts to think straight again, rather than beating each other up.

Sitting on your ar**s and saying 'I will not be moved' will only cause you more grief in the long run.

Just try to come into the real world for once, and look about you. Attempt to embrace a little of the metric system, and at least then, you won't have too much of a struggle when the inevitable happens, and as sure as the sun rises in the morning, it will happen at some time in your future, maybe sooner than you think.

Just another way of looking at things.


Blogs


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## Maryak

Last time we were in the UK, (2004), the speed was mph and road distances were in miles as were distances on the road maps we bought. One even said, "Scale of street plans 4" to 1 mile unless otherwise stated." 

Interesting. 

Best Regards
Bob


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## ToniTD1490

I like this discussion, Metric against Imperial, advantages disadvantages, ...  But what's is a Pint?


a. 1/8 gallon or 16 ounces (0.473 liter). (liquide)  US
b. 1/16 peck or 1/2 quart (0.551 liter). (dry measure) US 
c.  equal to 0.568 liter. (dry and liquid measure) British.

Someday will we be unified happily with only one system?
Someday ...

ToniTD1490


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## John S

Maryak  said:
			
		

> Last time we were in the UK, (2004), the speed was mph and road distances were in miles as were distances on the road maps we bought. One even said, "Scale of street plans 4" to 1 mile unless otherwise stated."
> 
> Interesting.
> 
> Best Regards
> Bob



The reason behind this is capitalism, note no Z, 

We had to make the change to metric in the 1970 by law, this included things like tools, scales etc being changed over BUT the cost was borne by the owners / users.

Because a change from miles to Km and even a swap to RH drive to match Europe ? will have to be borne by the government, road signs etc, training etc we have exemption from the EU :bow:

If the road system was in private hands they would have forced the change years ago.

John S.


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## Bluechip

ToniTD

20 Fluid Ounces = 1 Pint if you don't mind 

Were you once a Publican ?

Dave BC


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## Dan Rowe

The discusion about the merits of metric over imperial have been going on for well over 100 years, this made me think about the problem another way. I looked around the shop on a ship to try and find examples of things that would never be converted to metric. The ships I worked on were built in Japan with Swiss engines and English toilets. The Swiss engine had Whitworth threads. 

I thought of two items that I doubt will ever go metric, one of them is very common and anyone reading this will have an example in the shop, the other is not very common but it might be interesting to members of this forum.

I will let everone think about this before I give my answers because I think there must be more stuff I just can not come up with them.
Dan


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## ianjkirby

Hi all,
 I've been away for a couple of days, and am just catching up. I love debates about metric vs imperial units!
 I must recall several years ago a professor had us all re-calibrate out known worlds in terms of the accepted mass of the earth (mass), the time of a solar year (time), and the mean distance from the earth to the sun (length). We altered all of the commonly accepted units for many engineering constants, and thoroughly thought through (how's that for 'imperialism'!) what it all meant. I now have no misconceptions about units, as they are just various names for common things. As has been mentioned by several contributors, the distance between any two points is just a distance, regardless of what you call that distance. To a martian, it may be neither imperial or metric. I personally now prefer metric, despite having been brought up on imperial stuff, but if you prefer imperial, go for it! These days, its mostly just a click on a digital caliper button to change from one to the other.
 Someone mentioned cm and other 'metric' units. It is my understanding that metric systems prefer base units (kg metre second) and multiples or sub-multiples in terms of 10 to the power 3,6,9,... or to the power -3,-6,-9,...
Debate on, this is fun!
Regards, Ian.


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## Bynne

[pedant pedant]


			
				mklotz  said:
			
		

> [pedant]
> 
> 1/25.4 = 0.039370078... is an irrational number. That means that the decimal representation goes on forever whereas the 25.4 representation is exact since that's how the inch is defined.
> 
> [/pedant]



I just saw this, and I need to say that irrational means that you cannot write it as a rational expression, i.e. a/b where a and b are whole numbers. So 1/25.4 is rational since it can be written as 10/254. An example of a number that is irrational is the square root of 2.
[/pedant pedant]

Sorry about this, but you put it in pedant mode ;D


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## John S

Loose nut  said:
			
		

> The only way we can get the whole word onto one system is to throw out both the imperial and metric system and institute a new universal system that everyone will use, then we will all be the same, miserably unified.



Unified will not work, after the debacle of WWII America tried to force a change on the world with screw threads, mainly fuelled by the automotive industry that at that time owned or had fingers in most pies.

The UK, Europe and I think Australia were forced to adopt UN threads, as the ties got broken form corporate America so did the use of unified threads.

Because we lost our threads in the change over it was easier for us to adapt to the new Metrics that came into prominence.

Now only the US uses Unified threads, the rest of the world uses metric, eventually if the manufacturers, mainly in the far east, decide to only make a part,/ machine with metric threads what will happen? will you refuse to buy it ?

The rot has already started, you can now buy off the shelf R8 tooling with M12 drawbar threads instead of that bastard of a size, 7/16" UNF

I know this is of no concern to people with their own tooling but you have to look at next weeks sales and the next generation of owners.

John S.


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## ianjkirby

Hi all, ans John S in particular,
 It is my understanding that Australia was never forced, or otherwise, to accept UNC and UNF threads, They exist, in Australia, as just another odd thread that serves no other purpose than to confuse people who encounter them. Whatever their merits, they are not in common usage in Australia.
Regards, Ian.


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## bucketboy

I am happy with both but the big advantage in metric is the relationship between size-weight-volume-displacement-pressure


1000mm x 1000mm x 1000mm (cubic metre) = 1000 ltrs = 1000 kilos = 1 tonne

Or 100mm x 100mm x 100mm = 1000milli ltrs = 1 litre

10mts head of water = 1bar

Bb


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## Dan Rowe

As I mentioned the ships I worked on were a real mix of thread standards. The uncommon thing I mentioned is a thread standard..... only I have no idea what standard. The indicator cock of a modern diesel engine has the same thread as was used in steam engine days. The engine indicator was invented by James Watt and I have to assume that the thread came from his shop which predates Whitworth threads. The thread size is 1.0625"-10TPI. This is the oldest thread standard that I have ever encountered that is still in modern production world wide.

As this is really an instrument thread there have to be other technical items with obsolete thread standards still in use such as cameras. For those who play darts the threads are BA on dart bodes world wide.

Now for the common item.... the ratchet in your shop has a 1/2", 3/8", or 1/4" drive. It does not matter what country you are located in. The sockets in my tool box match the rachet in your tool box and that fact is not likely to change in the near future.
Dan


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## shred

Dan Rowe  said:
			
		

> As I mentioned the ships I worked on were a real mix of thread standards. The uncommon thing I mentioned is a thread standard..... only I have no idea what standard. The indicator cock of a modern diesel engine has the same thread as was used in steam engine days. The engine indicator was invented by James Watt and I have to assume that the thread came from his shop which predates Whitworth threads. The thread size is 1.0625"-10TPI. This is the oldest thread standard that I have ever encountered that is still in modern production world wide.
> ...
> Now for the common item.... the ratchet in your shop has a 1/2", 3/8", or 1/4" drive. It does not matter what country you are located in. The sockets in my tool box match the rachet in your tool box and that fact is not likely to change in the near future.
> Dan


Many light fixtures have threads that date back to gaslamp fittings. The CNC machines that make nearly everything these days can work in whatever units you choose. The "tyranny of the leadscrew" is done.

As others have said, the distance, weight, whatever is what it is and what you call it doesn't make that much difference, they'll just print both measures on the box.  Go look up plumbing pipe or lumber-- even though it's called 1/2" or 2x4, nothing about it measures 1/2" or 2" or 4".

I work in an industry that sells millions of units of high tech electronics all over the world-- everything is designed in metric and the legacy imperial stuff like connectors just have odd metric dimensions applied to them. In the US, they reconvert weights and measures back into imperial "14-inch screen size!" and drive on. The engineer in China trying to get the weight of the product under 907.18 grams may or may not know why, but it's what they do.

The annoying bit is for the hobbyists that don't have the resources to build that way.


----------



## tel

ianjkirby  said:
			
		

> Hi all, ans John S in particular,
> It is my understanding that Australia was never forced, or otherwise, to accept UNC and UNF threads, They exist, in Australia, as just another odd thread that serves no other purpose than to confuse people who encounter them. Whatever their merits, they are not in common usage in Australia.
> Regards, Ian.



Only in the automotive industry Ian, which has since, as we all know, 'gone metric'. Interestingly though, nearly 40 years after metrification here the common hardware store bolt is still Whitworth.


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## Maryak

Tel,

You got it. :bow:

I have 3 separate tool boxes of spanners, one with Whitworth spanners and sockets, one with AF spanners and sockets and one with metric.

Go look at the job then back to the shop to return with the appropriate tool box.

I even have metric and imperial hammers but that's due to their age not their usefulness. ;D ( Bloody things don't float :).

Best Regards
Bob


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## tel

Nah, not many of mine float either


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## max corrigan

Surprisingly car tyres (tires) use a mix of measurements ie. metric i believe for the width, percentage for the wall and wheel size in inches i might have got these definitions in the wrong order, but there are in the UK, at least these three measurements, i don't know about the rest of the globe though! 
Regards Max............


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## tel

And Schraeder valves are, as far as I know, still 5/16" x 40 tpi.


----------



## max corrigan

tel  said:
			
		

> And Schraeder valves are, as far as I know, still 5/16" x 40 tpi.


Tel that would throw another thread type into the pot ie. 5/16 x 40 tpi = ME (model engineering thread) interesting!
Regards  Max..............


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## MakMov

Who'd ever thunk the US would have something in comon with Libira and Burma, the only other countries in the world who have not converted to the metric system, which is quite annoying here because I mostly try to live in the the metric system, but they have made it very hard. 

I live in a big metro area and couldn't even find a metric drill bit set.


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## SBWHART

Just bought some ally bar off ebay for some reason they advertise the bar with the diameter in inches and length mm ???.

Stew


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## John S

tel  said:
			
		

> And Schraeder valves are, as far as I know, still 5/16" x 40 tpi.



Schraeder valves are specials to Schraeder

External Thread: 0.305 in OD, thread root diameter 0.302 in x 32 tpi (threads per inch)
Internal Thread: 0.209 in OD x 36 tpi.

John S.


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## doubletop

John Stevenson  said:
			
		

> Schraeder valves are specials to Schraeder
> 
> External Thread: 0.305 in OD, thread root diameter 0.302 in x 32 tpi (threads per inch)
> Internal Thread: 0.209 in OD x 36 tpi.
> 
> John S.



However, from my experience an ME 5/16 x 32 thread will "fit" a Shraeder valve connector despite 5/16" supposedly being .3125" O/D and the Shraeder OD being .305", as John points out.

On this dimensions thing; what's with drawings I've seen in my recent surfing that have imperial fractions, decimal inches and mm on the same page? Please don't as me to find one I've been to too many websites in the past two months since I joined the model engineering fraternity.


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## Jasonb

> On this dimensions thing; what's with drawings I've seen in my recent surfing that have imperial fractions, decimal inches and mm on the same page? Please don't as me to find one I've been to too many websites in the past two months since I joined the model engineering fraternity.



It is possible, a drawing primerilly in fractional inches may have the centres of a pair of gears in decimal inches as they are unlikely to fit an exact fraction and maybe a metric spark plug thread. Also some drawings use decimal inches to show where the tollerance is more exact than just using fractions.

But on the otherhand it may just be bad practice 

Jason


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## Tin Falcon

There are many factors that effect the style, quality readability etc of drawings or prints. 
1) Professional standards change over time
2) Standards are different in different parts of the world. 
3) Some of the prints are done by trained professionals 
a)Some self taught Rudy Kouhoupt for one
b) Or professionally trained. 
4)Then some / many are amateur hobbyists
  who may be professional draftsmen/designers or not.
There are many fine prints out there that were originally done the old fashioned way by hand some digitized.
and then of course Alibre cad and others has put parametric design into the hands of the armature hobbyist. 
There are also a fair number of redraws out there. Such classics like Lucy and the Macabe runner that were compact one sheet originals have been turned to one or two parts per page drawings by students. Free prints off the net are great but sometimes quality is lost. 
The projects in the old popular mechanics mags are great but they pack lots of info and detail in a small space. 
There is no real right or wrong style of print as long as the info is complete but some do need some thinkin' . 
Like I have mentioned before a re-draw sketch of each part on a 3 x 5 file card helps you understand the part, and is a ready reference at the machine. 
Tin 
Tin


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## tel

John Stevenson  said:
			
		

> Schraeder valves are specials to Schraeder
> 
> External Thread: 0.305 in OD, thread root diameter 0.302 in x 32 tpi (threads per inch)
> Internal Thread: 0.209 in OD x 36 tpi.
> 
> John S.



Oops, I meant 32 tpi. Thanks John. The odd few I've made fittings for I just use the 5/16 x 32 tap.


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## IDP

I prefer the imperial system but am slowly thinking of going metric for fastners as they are now easier to source.

If you do a wikepedia search 'Inch definitions' the ensuing answer makes very interesting reading suggesting that the unit of 25.4 mm to the inch is not correct as it makes a yard too long?

Regards,

IDP


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## Maryak

IDP  said:
			
		

> If you do a wikepedia search 'Inch definitions' the ensuing answer makes very interesting reading suggesting that the unit of 25.4 mm to the inch is not correct as it makes a yard too long?
> 
> Regards,
> 
> IDP



Maybe its' all happened because US legislated 39.37 inches = 1 metre in 1866. Whereas it is more like 39.370147 inches.

With an error of 2 parts per million I can't get overly excited, (makes me want another fag ).

Best Regards
Bob


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## tel

> 39.370147 inches.



Geez mate - I just round it to 39.37015"


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## Lew_Merrick_PE

MakMov  said:
			
		

> I live in a big metro area and couldn't even find a metric drill bit set.


That's because there is no such thing as a "standard" metric drill bit set.


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## Lew_Merrick_PE

The theory behind the metric system is that ten's are somehow "natural." Were that the case, harmonious scales would be based on 10 rather than 12 or 16. Just try using a base-10 system to analyze fluid flows, Earthquake propagation, or Kuanda-amplification of aerodynamics! Mind you, I grew up (until about age 10) using metric and "converted" to American inch/pounds/seconds back when the standard of American measurement was 1/128th's of an inch.

The original definition of the metre was to have been 10,000,000 metres from the equator to the North Pole. They screwed up THAT calculation. The kilogram was to be 1000 cubic-centimeters of water. They screwed up THAT calculation. The reason temperature is measured in Celsius degrees today rather than Centigrade degrees is that they screwed up the definition of ZERO and did not correct THAT until the early-1970's. In short, the metric system is a SET of screw-ups.

In most instances I care not whether metric measure or Imperial or American inch-based measure is used. My specific *gripes* have to do with the units derived from Pascals (N/m²). The "mesh" is *wrong*! The *units* provide no "feel" for the measurement being made.

I was the chief mechanical engineer on the program that developed the modern (late-1980's/early-1990's) automotive airbag restraint systems. [This sounds really impressive until you realize that (A) airbags are *chemical* rather than mechanical, and (C) I spent nearly three years working on a project that was *designed* to blow up in my face!] I worked with Japanese, French, and German engineers (among others) who had never used anything *but* metric measures. *They* would screw up their pressure/stress calculations *because* even *they* would get "confused" by the size of their answers. It's kind of like trying to report football (real or American) in *inches* -- the numbers easily became meaningless and someone exploded their unit (or failed to inflate the bag) as a result. In 1998, we lost a multi-billion dollar Mars Lander system because a French engineer lost track of the powers-of-ten in their answer for an airbag pressurization!

I have fought with metric screwthreads since the late-1960's. Until 2001, there were *five* "standard systems" of metric screwthreads (meaning major diameter and pitch) -- French ISO, British Standard, DIN, JIC, and American ISO. You have no idea how much "fun" I had installing RADAR domes for NATO in the early-1970's. Even today with "standardized" metric screwthread major diameters and pitches, there are *still* five different set of _tolerances and allowances_ in use. If you buy a (say) M6 bolt from a German supplier and a M6 nut from an Asian (JIC-using) supplier, there is a 43% probability that the nut will *not* mate properly with the bolt!

Making matters worse from *my* knothole, changing from a "standard" metric screwthread to a "fine" metric screwthread of the same major diameter only gains me *3%* on the strength/bending properties of that connection. The (currently) Unified National thread series (which derives from the WWI vintage "American-British-Canadian" standardization) gains me *15%* in connection properties when I change from _coarse_ to _fine_ or from _fine_ to _extra-fine_. [This was actually a *requirement* set out for the "ABC" committee by no less than Herbert Hoover!] Further, the "standard" (and "fine") pitches chosen for metric screwthreads are *too fine* for direct application in low-shear-strength materials. You *have* to use a "thread insert" whenever you face that proposition. [UNC threads work well in *most* low-shear-strength materials.]

Metric screw users like to claim that their system is simpler in that you only have to subtract the pitch from the major diameter to find the correct tap drill. (A) You can do the same thing using inch-based threads -- just just have to do the division to turn TPI into pitch. (B) The "answer" you get will only give you 62% (on average) of the maximum strength you *can* get with a properly calculated tap drill! [I have many documents about screwthread strength and tap drill calculation posted at http://www.scribd.com/Lew Merrick if anyone is interested.] Yes, this works well in *most instances*, but it does *not* work when you get into strength/mass critical applications.

Otherwise obsolete measures such as the league, furlong, and stone are important to understand. A league was the distance a Roman Legion would march in an hour. A furlong was the distance a Roman Legion was expected to run in five minutes. A stone was the mass an underfed peasant was expected to be able to "pick and place" all day long without keeling over and dying. Knowing about how these measures came into being gives a designer an understanding that is *missing* from more "modern" units of measure.

What "killed" the metric system here in the U.S. was the advent of the pocket calculator. Dividing by 386.35 (in/sec² for 1g) is now no harder than dividing by 10.


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## Dan Rowe

Lew,
I read your Brief History of the screw thread, very interesting. You did not mention William Sellers who was the first to propose standard threads in the US in 1864.
http://anniversary.asme.org/2005landmarks3.shtml

Dan


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## Maryak

Lew_Merrick_PE  said:
			
		

> In 1998, we lost a multi-billion dollar Mars Lander system because a French engineer lost track of the powers-of-ten in their answer for an airbag pressurization!



Poor guy was probably as confused as the rest of the world having been brought up on the *French cgs* system rather than the cobbled together mess of the current *Metric ISO* system with its' politically correct but difficult to feel numbers.

Best Regards
Bob


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## Lew_Merrick_PE

rake60  said:
			
		

> If you will excuse me now I need to go and recalibrate my adjustable Crescent
> Wrench. It is Imperial of course and I need it to work on my Suzuki Tracker
> tomorrow. Converting it to metric may keep me up all night!


Rick, the 1967 JC Whitney catalog had a "6 inch adjustable wrench" listed for $0.75. Towards the back of the catalog under "metric tools" they had a "15 cm adjustable metric wrench" listed for $2.25. I've always wondered how many people bough the "adjustable metric wrench."


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## Lew_Merrick_PE

Dan Rowe  said:
			
		

> I read your Brief History of the screw thread, very interesting. You did not mention William Sellers who was the first to propose standard threads in the US in 1864.


Dan, The reason I "ignore" Sellers is that he was far from the first person to propose standardization of threads. Virtually everything in his proposal was "researched" from Whitworth's work. {As Tom Lehrer sang so well, "Who made me a big success and brought me wealth and fame? Nicholai Ivanovitch Lobachevski was his name. In one word he taught me the secret to success in mathematics -- Plagiarize, let no one else's work evade your eyes. Remember why the good Lord made your eyes, so don't shade your eyes, but plagiarize, plagiarize, PLAGIARIZE! Only always call it, please, RESEARCH!" [ame=http://www.youtube.com/watch?v=IL4vWJbwmqM]http://www.youtube.com/watch?v=IL4vWJbwmqM[/ame]} Where Sellers really screwed up was in concentrating on radial rather than circumferential clearances in fits. Whitworth got it MOSTLY right, Sellers was completely off base.

The reason we have Number screw sizes today is that it was Ben Franklin's proposal to simplify things for the stove industry. Franklin was a "decimalist" -- that's why the #0 screw has a .0600 major diameter rather than .0625. He *wanted* the progression to be made in .020 increments, but he ran into Poisson's ratio when trying to draw iron -- which is how we ended up with .013 increments for Number sized screws. If you are looking for the first person in the U.S. to propose a standard for screw threads, Ben Franklin is your man.

Sellers got the credit, but the idea had been kicking around for many years with many backers. MY "point" is that we did NOT get a real and enforceable set of standard screw sizes based in functional mechanics until the American-British-Canadian (ABC) Industrialization Council set up for WWI. Not only do I stand by that assertion, I _suggest_ that this was the acme of standards development that *should* be required study for anyone in engineering or regulatory work.


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## gweloboy

I am not sure where the .039... conversion factor comes from. 
Inch to mm - inches x 25.4
mm to inch - mm/25.4

A whole lot less numbers to remember!


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## gweloboy

Here is my bit of info. I went on a bolting course given a Swedish bloke about 10 years ago.
He recognized my accent as Rhodesian not South African.
He told us fine threads were an attempt to stop nuts coming loose before effective locking systems were developed.
He told us that no-one was doing any research on Inch bolts, all was being done on metric bolts.

I took some science classes at the local college and realized why metric struggles here. The compulsory Imperial/metric conversion lessons are seen as not much more than arithmetic/mathematics exercises. As a child overseas I remember the change to metric. At the beginning of the school year everything went metric -that's all you learned. All new machinery was metric. We learned to convert because all existing equipment was in Imperial. S.Africa went so far as to ban any Imperial measuring equipment - no metric/inch tapes etc allowed.


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## Cogsy

I know it's a super old post from a super old thread but I had to laugh at Lew Merrick's comments about what the SI units were based on and how they "screwed up" the calculations. While it's true the definitions have been altered and refined, ever closer to a 'perfect' and repeatable quantity, they didn't "screw up" the calculations, it was just the best standard they could apply. Meanwhile, Lew doesn't mention the basis of the definition of an inch (width of an 'average' man's thumb) or foot (length of an 'average' man's foot) or yard (length of an 'average' man's belt), etc., etc. And what did they finally settle on to truly define the inch, foot, yard, pound, etc. - they are all now officially defined against the metric standard.

Oh, and the Mars lander (Mars Climate Orbiter) that was lost was due to a Lockheed-Martin failure where their equipment produced output in American customary units when the rest of the mission expected (and as they were contracted to provide) SI units. No "powers of 10" issue there.


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## rodw

Cogsy, I'm on your side. Like you I live in Australia which converted to metric in 1966 with what is acknowledged as being the most successful metrification project ever ran. Like you I am old enough to remember the conversion and being taught how to do maths in imperial units in school. Wow! how good was it to work in litres instead of pints, quarts and gallons! 

Yes I remember we got dragged kicking and screaming into the metric system but it all changed in 1978 when I started to study engineering at University. In semester 1 we had to purchase a little book called "SI units" that was filled with conversion factors and explanations of the more complex metric engineering units. About once every 5 years, I still pull it out to check to check something like the relationship between kPa and bars, but I've never referred to it for conversion factors for the last 30 years.  

Like you, during those early days, my head became filled with useless conversion factors like 25.4, 3.28. 0.3048, 2.471, 2.204 and many others. But eventually I succumbed and banned imperial measurements from my life and can now use those brain cells for other purposes. I recall, how I could once work in fractions with ease, but now it is a distant memory. I have a set of AF sockets I bought way back in 1978 that have not been used for years....

The last conversions in my mind to fall were land areas (it was much cooler to say I grew up on a 100,000 acre property than one that was only 40,000 Ha). The other one was rainfall. 100 points was embedded much more deeply than anything else given my rural background where rainfall was so important as it was almost a religious experience to empty the rain gauge when it finally rained (25mm was soooo boring). 

I am pleased you corrected the reasons for the loss of the Mars spaceship as the excuse offered also clashed with my memory of the incident. Lets face it. Every major engineering project in the world has used SI units for years and this project was bought undone by a team that did not use them.  

The fact remains that only 3 countries in the world cling to the imperial system. One of them actually corrupted the base units so back in the day, I had a whole host of secondary conversion factors for US gallons vs real gallons.

I just did a bit of quick research on Google and it just so happens that of there are 7 billion people living on this planet. But those 3 countries represent just 5.38% of the worlds population.

Eventually, you guys in the US will succumb and you will finally acknowledge you are a very small minority group. You will embrace the global standard. Yes, there will be much gnashing of teeth and wringing of hands just like there was in Australia back in the 60's and 70's. But remember, you are a country of 318m people and billions of others have converted to metric and survived. Surely, such a small handful of people can also make the grade.


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## RonGinger

I found a very interesting document by the NIST on metric in the Us. http://https://www.nist.gov/sites/default/files/documents/pml/wmd/metric/1136a.pdf

Looks like a lot of government purchasing is now in metric, but we still have the 'freedom' to use whatever we want, hence the mess of units.


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## Cogsy

As SI units are the official 'language' of science, it's interesting to hear seminar talks from American scientists fluently, and intuitively, speaking in SI units. They were bought up using imperial for everything but their careers necessitated a change which they obviously underwent. I wonder what units they use in their 'everyday' lives, do they think of a summers' day in degrees c or f, meat in lbs or kg, milk in L or fl.oz? I'd guess whatever they're most comfortable with, which I further assume is metric. My parents were born, raised and working full-time for years before metrication but completely made the change long ago - except, as Rod says, they still live on acres of land.

Edit to add: Ron, your link was off a bit - https://www.nist.gov/sites/default/files/documents/pml/wmd/metric/1136a.pdf

Another edit: I read the paper Ron found and it was interesting, just a note though - mL is a volumetric measurement, for dry ingredients for a recipe (or even quantities in chemistry, etc.) we use mass measurements in grams. We only use mL or L for fluid or gaseous quantities.


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## rodw

In my first year at university in 1978 when most of us worked in imperial units in everyday life, the lecturer calculated the power output by an engine in SI units and came up with the result in kW. It took half a blackboard.

He then redid the same sum in imperial units and came up with the same result in Horsepower which saw him fill 3 blackboards before announcing to the assembled students "And that's why in Australia we prefer SI units!  It was a powerful incentive to get our head around the new SI units. I had never even heard the term SI units before.


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## gunna

I have always wondered at U.S. tv shows like CSI and Bones which routinely quote metric units for distance and weight. I thought they were just trying to be "scientific".
Ian.


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## ShopShoe

In interacting with my own doctors and taking my mother to hers, It's mostly metric: Doctor tells me the size of things in mm and tells me to drink 3 litres of water a day. Docter tells Mom to gain 10 lbs and drink 10 8-oz. glasses of water.

My wife is a nurse and we tend to use units interchangeably without problems.

In addition to a fondness for metric units, our personal inclination is to use 24-hour time: Every clock we have that allows it is set to do so. I was never in the military, but I think it makes more sense.

--ShopShoe


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## blighty

had a mate years ago, when we were kids  building a fort, tree house, go cart etc. he would say cut this off at 3feet 1 inch and 5mm. as long as i cut it at 3feet 1 inch and 5mm it would fit. if you look at a tape measure with inch/mm, it makes sense.


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## Rig30mechanic

I was educated in a time when Australia changed from Imperial to Metrics and have worked in engineering for the past 47 years. Many of these years were on oil rigs both on land and offshore.
The idea of measuring distances by using fractions of a dead Kings smelly foot is difficult to understand when we have available a simple system based on the number of fingers on a standard person.
To be able to add in 10's is pretty easy.
I have even had to work with "oilfield" tapes where the feet" were divided into tenths to make addition and notation easier. It would have been easier to use metrics.
Congratulations on seeing the light.


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## goldstar31

It's probably a bit over the heads of some, but the arguably feasible answer is the 'Megalithic Yard' which the ancients calculated from the Planet Venus. 

What remains is the Railway Gauge of 4 feet 8 and half inches which no one has yet to fathom( ouch). It certainly is not English and I went through all this with a French Professor of English. We were having fun with the origin of haggis and I reckoned that is was from the Norman French and the Grande Alliance of France and Scotland and merely meant 'minced' Well, the Railway Gauge is from the Roman Wall of which there were two and was obtained from the ruts of Roman Chariots which were ground into the stone of Hadrians' Wall.

And who adopted the gauge first, we know that it was from the wooden railways that took the coal down to the River Tyne and the first steam locomotives that used the gauge came from none than George Stephenson of Canny Wylam on the Tyne and his Rocket.

Laughingly, I seem to have  quite a bit of that Wall as my boundary wall. There's a bit of Anglo Saxon stuff next door-- but I digress 

Norman


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## Wizard69

Rig30mechanic said:


> I was educated in a time when Australia changed from Imperial to Metrics and have worked in engineering for the past 47 years. Many of these years were on oil rigs both on land and offshore.
> 
> The idea of measuring distances by using fractions of a dead Kings smelly foot is difficult to understand when we have available a simple system based on the number of fingers on a standard person.
> 
> To be able to add in 10's is pretty easy.
> 
> I have even had to work with "oilfield" tapes where the feet" were divided into tenths to make addition and notation easier. It would have been easier to use metrics.
> 
> Congratulations on seeing the light.




Starret sells steel rules with the inch divided into 50ths and hundreds.   In the machine shop it makes perfect sense.  

There us a lot of stupidity in America with respect to the metric system.    I work in the optics industry which has pretty much always been metric. Companies will build tooling and machinery with all the drawings in english units.  Yet the parts being made are very much dimensioned in metric units.  Strange.


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## Mechanicboy

Inches were not always equal to 2.54 cm. Inches measurements were not as long in different countries. In the same period before it was determined that 1 inch should be equal to 2.54 cm in 1959, the definition was determined in an agreement between the United States and the British Commonwealth in 1958.
1 Scottish inch = 2.5441 cm, 1 French inch = 2.70 cm, 1 Roman inch = 2.47 cm, 1 Norwegian inch 2.614 cm.

England was traditionally the largest export market for Norwegian wood loads, and then it was practical that the British inch is slightly below 1 mm shorter than the Norwegian inch. The wood plank that were cut after Norwegian inches up would then get about the same measurements in English inches after drying.

How painful and expensive could it be when a German workshop used a working drawing with dimensions set on the drawing from Italy to make spare parts for a locomotive that was manufactured in Italy and then find that the parts did not fit due to the machine operator did not think that the measure were measured after Italian inches and measured with a German inches measuring tool during work. 

"Give him an inch and he'll take a mile"


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## gweloboy

I wish the local Chinese lathe vendors would give us the  option of  metric or Imperial like they do in the UK. I asked Big Dog if they would  bring in a metric machine and received an emphatic NO. So much for  customer satisfaction.


----------



## Jasonb

Infact the choice of imperial versions here is getting less, many of the latest hobby lathes are now only being sold in metric in the UK.


----------



## kadora

Here in Slovakia I can buy 10 mm drill bit for 1.5 EUR
but half inch drill bit costs me 10 EUR.

I am happy we have the same circle division to 360 degrees
and time to 24 hours.


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## goldstar31

kadora said:


> Here in Slovakia I can buy 10 mm drill bit for 1.5 EUR
> but half inch drill bit costs me 10 EUR.
> 
> I am happy we have the same circle division to 360 degrees
> and time to 24 hours.


 
I suspect that a 1/2" drill will be more than that in the UK.

However, there is a shortage of 'tenths of a millimetre' drills as well.

I'm on with a metric Eccentric tool and cutter grinder which calls for such drills and as most drill chucks are far from accurate( mine especially), I'm forced to break into my sets of  Fractional and Letter and Number  drills  to compensate.

Not a perfect solution but worth a mention?:wall:

Norm


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## Mechanicboy

No problem to buy 12,7 mm drill who are same as 1/2" inches drill  

https://www.amazon.com/dp/B0033B0STQ/?tag=skimlinks_replacement-20


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## Jasonb

Norm

Should not be a problem getting metric drills in 0.1mm steps, I have had a 1.0-6.0mm set for about 30 years and never had a problem buying replacements. Got a 6.0-10.0 set a few years ago and easy to top that up if needed.


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## goldstar31

Just received the new catalogues for Tool Station and Screwfix.

Plenty of drills but 0.5mm intervals.  It happens when you are 87. Not a lot of us about but if you are COPD, a post box means a taxi!

But thank you, it may help others

Norm


----------



## Jasonb

To be fair to Toolstation and Screwfix they are not engineering suppliers

Try someone like MSC who have 0.1 increment drills from about six differnt makers in jobber and stub lengths, slightly more limited in teh long and extralong series. If you want to use one of the ME suppliers then Greenwood Tools do the Dormer A002 split point ones individually.

http://www.greenwood-tools.co.uk/shopscr130.html

J


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