# The Great Metric System Debate.



## kcmillin (May 15, 2010)

Some Comedy from a friendly family debate, based on a true story. And proof, that I win every debate that I enter. This is not meant to affend anyone, and is only the thinking of one person, but worth a read.


The Great Metric System Debate
==============================


ME = My Brother. And Her = My Neice




HER: Dad, I need money for a haircut


ME: Why do you need a haircut?


HER: I need to take a few centimeters off the back


ME: Centimeters? - Who the hell is teaching you to use centimeters to measure your hair. Liberal teachers are infiltrating and taking over our entire education system.


HER: Dad, centimeters are small, and I just need a LITTLE off


ME: You mean 1/2 Inch


HER: No - a few centimeters


ME: Yeah - try asking your stylist to take off a few centimeters, and she will look at you like you are a crazy French woman


HER: What are you talking about


ME: The French - they invented the flawed way of measuring things now known as the "Metric System"


HER: Everyone uses the metric system, except for us... Maybe we are the ones with the flawed system


ME: WHAT! - Nothing American is flawed, including our system of measurement, plus, we aren't the only ones, I am pretty sure Liberia uses our system.


HER: Liberia


ME: That's right, Liberia. Don't you see, our system is far superior. Who knows what a centimeter, or meter or kilometer actually is? - I sure don't. But I do know what an inch is, a foot, a yard and a mile. All of them perfect. 12 inches in a foot, 3 feet in a yard, 5280 feet in a mile.  It all makes perfect sense. And we can get small too... half-inch, quarter-inch, eighth-inch, sixteenth-inch - you see, never ending, and easy to remember. Don't even get me started on Rods, Fathom's and Leagues. 


HER: Metric system everything is divided by 10's


ME: Dumb right?


HER: umm...no...much easier


ME: See what I am saying? - "Easy" equals "Lazy" equals a well thought out plan by the French to take over the world and make us all have 35 hour work weeks and 28 paid holidays a year.


HER: Sounds good to me


ME: And furthermore, the Metric system is based on an incorrect measurement of the circumference of the earth...The guy that tried to figure it out, screwed up, but was afraid to tell the king of France. So now, the entire Metric system is based on an incorrect measurement. Imagine if we started using it, everything that we measure would be WRONG!! We'd have crooked houses, and leaning buildings - thank God for Feet and Inches


HER: Are you kidding me...really?....Does it matter how it was made? - no....The "Foot" was based on the length of some King's ACTUAL foot, how flawed do you think that was?


ME: I am sure he was an excellent king, with a foot, that was EXACTLY 12 inches long. See, everything fits.


HER: Oh my God


ME: Do you really want the French to take over? - Look what they did to Quebec


HER: The French are not going to take over


ME: To prove my point, do you know how many Kilometers is it from Bismarck, ND to Eugene, Oregon?


HER: I have no idea


ME: Exactly, nobody knows kilometers, because in America, we use Miles


HER: Ok then, do you even know how many "Miles" it is to Eugene, Oregen?


ME: Of course I do.


HER: Obviously you don't


ME: Ok - Fine, I have 2 words for you: "Mars Polar Lander"


HER: What...


ME: "Mars Polar Lander"


HER: That's 3 words


ME: Maybe so, but those 3 words represent a spaceship, that CRASHED into the surface of mars, instead of gently "LANDING" - Do you know why?


HER: Please tell me


ME: The Metric System


HER: Dad...Shut up


ME: It's true, some idiot put into the computer measurements in Meters instead of Feet....And what happened? - It Crashed. If not for the Metric system, the Mars Polar Lander, would have actually landed, but no, the French sent us the "Mars Polar Crasher" instead


HER: Or, maybe, just maybe, the French had NOTHING to do with the crash, AND if we started using the Metric System LIKE EVERYBODY ELSE, this would have never happened. 


ME: Ok smarty pants, do YOU know how many Meters it is from Mars Orbit to the surface of Mars? - I don't think so.


HER: When you argue with me, you just make stuff up to support an opinion that you obviously know is wrong but you are afraid to admit. Dad, just admit it, I'm right, you're wrong, Metric system is better.


ME: Not according to the NFL I'm not


HER: I don't care


ME: Yeah, well, Tony Dorsett sure cares. He still holds the longest Rushing Touchdown record at 99 yards.  Are you telling me that you want Tony Dorsett to be stripped of his record in the Record Books? Or worse, have his record written as "90.5256 Meters" - Doesn't really roll off the tongue now does it?? Not only that, but what would you have the Indy 500 renamed to? - "The Indy 804.672"? - I am sure drivers and spectators would flock from Miles (er. Kilometers) around to witness the Historical Tradition of the Annual Indy 804.672.


HER: I'm not arguing with you anymore


ME: Because I am winning?


HER: Because I Won, a looong-time-ago


ME: Communists use the Metric system you know. Apparently that is what you want for us, to live under the harsh oppressive rule of a communist dictatorship. How many square METERS of land do you own? - NONE - because the government owns it and has stripped you of your private property, and convinced you that they know best leaving you a sad and dependent soul who knows not the joy of owning your own 10 acre parcel of land.  Thank you honey, for ruining our country and everything we believe in.


...


HER: Dad?


ME: Yeah


HER: I still need a haircut


ME: Why


HER: I need to take a 1/2 inch off the back.


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## Maryak (May 15, 2010)

Reminds me of when my daughter was a teenager. ;D

Bloody Brilliant. :bow: :bow:

Best Regards
Bob


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## tel (May 16, 2010)

;D ;D ;D ;D


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## SAM in LA (May 16, 2010)

Kel,

Great story.

It sounds like a Carol Burnet/Tim Conway skit.

 Rof} Rof} Rof} Rof}

SAM


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## mu38&Bg# (May 16, 2010)

This reminds me of trying to communicate with my mother-in-law. "Facts" made up on the spot to win her point of view.

I think the point is that cutting 1/2" of hair is too expensive  I have some shears in the shop....


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## itowbig (May 16, 2010)

Rof} ha ha that sound exactly like me and my daughter Rof} that was great thanks


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## mklotz (May 16, 2010)

This would be funny were it not for the fact that many Americans actually believe these specious "arguments" against the metric system.


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## mhh (May 16, 2010)

Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof}

It is SO nice to see that the american youth is on the right track!


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## Deanofid (May 16, 2010)

mklotz  said:
			
		

> This would be funny were it not for the fact that many Americans actually believe these specious "arguments" against the metric system.



What "specious arguments"? I mean, if your not smart enough to find a common denominator, yeah, go ahead and use the "I-can-only-divide-by-ten" system.
You know?

 ;D

Dean
5/8 + 5/8 = 10/8
It's easy!


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## mklotz (May 17, 2010)

So, Dean, you use a micrometer calibrated in 1/128 ths of an inch?


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## Dan Rowe (May 17, 2010)

I have several vernier calipers that are calibrated in 1/128....I do not find them very handy and use the lower metric scale.

Dan


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## Deanofid (May 17, 2010)

mklotz  said:
			
		

> So, Dean, you use a micrometer calibrated in 1/128 ths of an inch?



Naw. For the kind of work I do, don't need much better than sixteenths!
No sense going overboard.


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## tel (May 18, 2010)

> 5/8 + 5/8 = 10/8
> It's easy!



OK - 5/8 + 5/8 + 11/32 + 27/64 + 1/2 + 11/16 + 31/64??


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## Maryak (May 18, 2010)

tel  said:
			
		

> OK - 5/8 + 5/8 + 11/32 + 27/64 + 1/2 + 11/16 + 31/64??



= 236/64 = 3 11/16 ??? or 93.66233775


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## Deanofid (May 18, 2010)

There, see? Bob is fully qualified!
(for fractions. I dunno if the that last silly bit is correct.)


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## kf2qd (May 18, 2010)

Hey man - Metric is great - IF you grew up your whole life using it. Otherwise it is a royal pain in the.. whatever. I understand metric, but it is just too much bother to convert to a system that I have never had to use and in reallity offers no real benefits. One can measure just as accurately in either system. It is also easier to divide thins in half, as we do for all the franctions - 1/2, 1/4, 1/8, 1/16, 1/32, 1/64 than it will ever be to divide things by 10. (Fold this paper into 10 equal parts...)

And we all know that the "standard meter" myth (that is is some portion of the distance from the north pole to the equator) was just an attempt by the French to try to justify a system that was really based on dividing the inch into 25.4 sections because they screwed up and failed to divide the inch in 25 segments. Then the Milimeter and the Meter would both have made sense.(25 millimeters to the inch and 40 inches to the meter) But because some Frenchman used some poorly made (Non-Starret, non-Mitutoyo) tools to measure out his NON-INCH millimeter those who use the millimeter have to put up with odd dimensions. And it is interresting that they try to this day to blame it all on the Americans when it was really just the result of some tizzy between the British and French going back who knows how far. The British have made a feeble attempt to placate the French (the british are europeans after all...) but what with stones and other silly units of measure they have still managed to stick it to the French. So the last bastion of sense and reason is the U. S. of A. who still have enough brass to uphold the noble, sensible and reasonable INCH, FOOT, and YARD as the only proper units of measure.


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## tel (May 18, 2010)

Maryak  said:
			
		

> = 236/64 = 3 11/16 ??? or 93.66233775



 ;D Now try doing it in yer head while running a machine!


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## Maryak (May 18, 2010)

tel  said:
			
		

> ;D Now try doing it in yer head while running a machine!



Yeah right 

For me the bottom line is fps "feels right" metric is probably the same for those raised on it. e.g. I know when I look at a piece of round bar I think aha 3/8." A metric guy would think aha 10 mm, we both go on our way at peace with the world.

Best Regards
Bob


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## kcmillin (May 18, 2010)

Maryak  said:
			
		

> For me the bottom line is fps "feels right" metric is probably the same for those raised on it. e.g. I know when I look at a piece of round bar I think aha 3/8." A metric guy would think aha 10 mm, we both go on our way at peace with the world.
> 
> Best Regards
> Bob



In all reality your completely right. There is no such thing as the better way. Just how you see it in your head. A measurement is not exactly real. For example. If you make a connecting rod that measures 3 inches (or whatever) you could easily just say it is 1 "connecting rod" long, you would not be wrong. The use of a standardized system is only to make it easy to communicate measurements. My personal "go to" system is English, but If I had a choice on which one I understood best, it would be metric.

Kel


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## mu38&Bg# (May 18, 2010)

When I was at NAMES there was a vendor selling digital calipers. They read mm, inch, and fractional inch. I've probably bumped into them before on ebay , but never paid attention. 

http://www.amazon.com/dp/B000UCIGCW/?tag=skimlinks_replacement-20

My old vernier scale caliper is wearing me down. I just might have to buy a decent dial or digital.


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## ieezitin (May 18, 2010)

To all those who are traditionalists quit bitchin.

Use your brain god gave you and work your problems out mathematically. Math is a universal law. Metric, imperial its all the same.

The Egyptians built the pyramids to a square x height ratio with a wheel running round a wheel from a cow cart. They did not know what P-r-sq was, it worked.

God! Even calipers today convert metric to imperial at the flick of a button, how easy can you get it.

dont mean to come off crass it is what it is.

Anthony.


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## tmuir (May 18, 2010)

I prefer metric as its what I'm used to but I find a lot of the stuff I make needs to be made in imperial, especially when I'm fixing something.
I've always in the past had to convert everything to metric and work to that, mainly because I only had metric micrometers.
I finally got myself an imperial M&W micrometer the other week so now when I make something in imperial I don't need to convert it. 

The bottom line is the only time I get upset with the difference between imperial and metric is when I find I need a 10mm bar or drill and I've only got a 3/8 inch, or the other way round.


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## Paolo (May 18, 2010)

Hi kcmillin 
I agree with your daughter...an hair cut of few centimeters is chipper than one of few inch quarts.... Rof} Rof} Rof} . Please use metrics I'm really bothered :rant: :rant: :rant: by the convertions from inch to millimeters, doing some works originally drown in inches, for reaching a good matching despite of the abundant decimals.... ??? ???
Best regards
Paolo
 :big: :big: :big: Rof} Rof} Rof}


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## rake60 (May 18, 2010)

ieezitin  said:
			
		

> To all those who are traditionalists quit bitchin.
> 
> Use your brain god gave you and work your problems out mathematically. Math is a universal law. Metric, imperial its all the same.
> 
> ...



Anthony *THAT* is a *PERFECT* answer! :bow: :bow: :bow:

A size is a size. It doesn't matter if it is in tenths of a centimeter or thirty secondths of an inch.
Either way you will hit it or miss it.

You can't blame the measurement system for making it more difficult.
 

Rick


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## gjn (May 19, 2010)

I'm with Bob, being on the wrong side of 50 I think and visualise in imperial measurements. I can visualise inches, feet etc but can't do the same in metric, I find myself converting back to imperial in my head to get an understanding of what is being described. All my welding work is in feet and inches.

Same goes for fuel mileage - I buy fuel in litres, read the kilometres off the speedo then convert them back to gallons and miles to get mpg. I know that 20-25 mpg is good for my truck, I have no idea what 10 l/100 km is.

Strangely enough though, for someone raised on imperial, I find that when I'm working on the lathe, but only for for small work (under 1/4"), I gravitate to metric - I have no idea why this is, it just happens.

We went through the same thing in 1966 - my grandmother never worked out decimal currency. Until the day she popped her clogs I had to convert dollars and cents back to the "real" money for her every time.


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## tel (May 20, 2010)

Hmm ... I'm well into my 60's, but I'm equally comfortable with both systems - just depends on what I'm doing, with what material at any given time. I was bought up on Imperial but worked in both the building and fabrication industries at during the era of the change.


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## Lew_Merrick_PE (May 20, 2010)

mklotz  said:
			
		

> So, Dean, you use a micrometer calibrated in 1/128 ths of an inch?


Hey, are you going to laugh at my (1932 vintage) 1/256th's micrometer?


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## Lew_Merrick_PE (May 20, 2010)

mklotz  said:
			
		

> This would be funny were it not for the fact that many Americans actually believe these specious "arguments" against the metric system.


Marv, Until you've watched French, German, and Japanese engineers scrambling across 5 acres of land looking for the pieces from their inflator that failed because they misread the powers of 10 in their Pascal calculations, you don't know just how "good" the metric system is. Why is it that so many "metric countries" have changed from N-m to kGf-cm for torque? Have you ever tried to apply an M10 (X1.5) screw to a cast aluminum part?

These all indicate that the "mesh" of Newton-derived units is pretty poor. It can be truly funny to look at the rework budget for companies that have gone "all metric" as they fail to realize that there are *still* five different and incompatible standards for tolerance and allowance with respect to metric screwthreads. I have lived through three fairly major _adjustments_ to basic units of the metric system -- it is still a _work in progress_ at best.


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## mklotz (May 20, 2010)

Lew,

The fact that a bunch of engineers can't do arithmetic reliably in their chosen measurement system is hardly an indictment of the system. If it were, the Imperial system would be long gone. You're not much of an engineer if you don't do order-of-magnitude and sensibility checks on what you compute.

Arguments about the engineering uses of the system, e.g., thread standards, are equally hollow. Practical thread standards can be calculated and expressed in any measurement system. You're damning the system because of the use some humans have made of it. Measurement systems are not collections of engineering standards.

I do agree that the current metric practice of using only 10^(3*n) multiples is ill-conceived and we should return to the 10^n progression. Nevertheless, the advantage of the metric system concept lies in its internal consistency, the simple relations among units, the logical connection between weight and volume, and the explicit separation of force and mass.

As a challenge, sit down and design your own ideal measurement system - not a system of engineering standards but a generally useful measurement system. I'm betting that, if you do a careful job of it you'll arrive at something remarkably similar to the MKS system.


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## bentprop (May 20, 2010)

This debate has been raging on and off for a 100 years in the english Model Engineer magazine,and still comes up now and then.
I agree with Marv that metric is a more logical system,and most countries are now metricated or working towards it.
But then,I would say that,having been brought up on metric,and having to learn imperial when I first arrived in nz in the early 70's,that metric is much easier to grasp.
If you can count to ten,you can deal with metric.
Of course,I DO have metric and imperial drill sets,and taps and dies for MM,BSW,UNF,UNC,BSB,BA,and god knows what else :big:


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## dsquire (May 20, 2010)

To All

I'm just going to stand on top of the fence and pee down both sides as there are good and bad things about both systems in my opinion.

I am going to provide a link to another Metric/Imperial Debate. :hDe:

*For the love of GOD use metric!*
http://www.cnczone.com/forums/showthread.php?t=18176&highlight=Metric+Debate

Cheers 

Don


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## Lew_Merrick_PE (May 21, 2010)

mklotz  said:
			
		

> The fact that a bunch of engineers can't do arithmetic reliably in their chosen measurement system is hardly an indictment of the system. If it were, the Imperial system would be long gone. You're not much of an engineer if you don't do order-of-magnitude and sensibility checks on what you compute.



Marv,

*That* is the entire point of my rant. If I am working with stress in psi I *know* that the answer I am looking for is going to end up being 1000's of psi (i.e. ksi). If I am working with stress in Pascals, my answer *could be* valid as MPa or GPa or even (with some of the newer materials) TPa. There is no immediate feedback as to the order of magnitude value that sends me looking for errors or mistakes. This is as true for engineers who have never used anything *but* the metric system (such as the French, German, and Japanese engineers I worked with while developing automotive airbag restraint systems) as it is for anyone else.



> Arguments about the engineering uses of the system, e.g., thread standards, are equally hollow. Practical thread standards can be calculated and expressed in any measurement system. You're damning the system because of the use some humans have made of it. Measurement systems are not collections of engineering standards.



You bet your sweet @$$ I condemn uses where the *application* fails to provide consistent results. *I* built radomes for NATO many years ago (i.e. back when there were *five* separate "standards" for metric threads). The system, built, qualified, and working fine in the Canadian north had to be *completely* redone when we went to install it in Norway (which uses the DIN standard set) and *all* the calculations redone to account for the different thread pitches and tolerances -- and redone *again* when it came to French installation!

While things are somewhat better today with respect to major diameters and pitches, the _tolerances and allowances_ (which you need to know when applying critical loads to threaded connections) are *still* based on varying standards. (This is one reason that the aerospace industry *everywhere* uses Unified National fasteners.) Under current ISO practices and standards, a German made bolt has a 42% chance that it will *not* mate with a Japanese made nut. You bet your sweet @$$ that this gets me up on my soap box screaming!



> I do agree that the current metric practice of using only 10^(3*n) multiples is ill-conceived and we should return to the 10^n progression. Nevertheless, the advantage of the metric system concept lies in its internal consistency, the simple relations among units, the logical connection between weight and volume, and the explicit separation of force and mass.



And this is the *ultimate failure* of the metric system! The unit of force, Newton, is so poorly meshed (1 N = .225 lbf) that the _kgf_ (kg-force) has begun to supersede it. I purchased a job-lot of 200 metric torque wrenches for NASA back in 1982. They came from France and had their calibration in _kg-m_ rather than _N-m_. Nobody (but me) thought that this was strange (or wrong)! I just did a critical structure design for a Japanese company. *They* insisted that all torques be specified in _kgf-cm_.

When you go to the store in (say) France and purchase a kg of (say) cabbage, the *measurement* they use when portioning out your cabbage measures *force* -- not *mass*! As a result, the *only* advantage of the metric system (differentiation between force and mass) is *lost*!

The "logical connection between weight and volume" is *density*. The "problem" is that kg/m³ becomes a massively unwieldy number in a hurry. Analysis systems that are supposed to be metric (_SolidWorks_, _Catia_, _ProEngineer_, etc.) have started using kg/cm³ over the past two decades. The metric *tables of densities* use kg/m³ -- and the ease with which that value gets screwed up is amazing -- even for engineers who have *never* used anything but the metric system (I see this all the time).

As I said several posts ago, metric lengths do not bother me in the slightest. Neither does Celsius temperature (though *I* am still personally PO'ed at having bought into metric tooling at the time when the change was made to the base metre and Centigrade was replaced with Celsius). That's all well and good, but the *Newton* and all the units that derive from it *suck* as units of measure in the *real world* -- and the proof of that is the prevalence of _kgf_-derived units appearing to replace it -- even in "totally metric" countries!

One of the companies I have done a lot of work for coined the phrase, "There's the few and then there's Lew." I admit to the truth of that statement. *I* design _mission critical_ components all the time. The strength of threaded connections is often the deciding factor as to whether or not a design works or fails. There are *nine* theoretical combinations of size, tolerance, and allowance based factors that determine a Unified National thread series connection's properties. (In actual practice, there are five.) There are (4^5 =) *1024* actual combinations of size, tolerance, and allowance that must be considered when applying metric threads in a similar situation based on the "standards" as they sit today.

This is why *I* say that the metric system is a set of *non-*standards!


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## Royal Viking (May 21, 2010)

I have tried to keep up with the posts, forgive me if I say something already posted.

Just this week I had gone out to the shop to do some quick guestimates on the floor area available for a project we are planning and I had walked out the distance using my feet for a quick measure. The drawing did not have to be to scale just proportional. I was helping my daughter work on some math conversions based on inches, feet, yards, gallons, and so on and it occured to me today that if I were using the metric system to what I had done at work it may not be so easy (i.e. If I wanted a quick measure of somehting using my forearm I could then relate that to someone else in a cubit's measure). How does someone who is used to the metric system apply the same situations to a measurement in metric?


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## tel (May 21, 2010)

> When you go to the store in (say) France and purchase a kg of (say) cabbage, the measurement they use when portioning out your cabbage measures force -- not mass! As a result, the only advantage of the metric system (differentiation between force and mass) is lost!



How in the blue blazes do you come up with this? If I put a cabbage on the scales and the needle deflects to 1kg that's weight (mass?). If I hurl it at someone's head and it knocks their hat off that's force.


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## SAM in LA (May 21, 2010)

tel  said:
			
		

> How in the blue blazes do you come up with this? If I put a cabbage on the scales and the needle deflects to 1kg that's weight (mass?). If I hurl it at someone's head and it knocks their hat off that's force.



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## mklotz (May 21, 2010)

Tel,

In physics weight and mass are two distinctly different things.

In Newton's famous equation,

F = m * a

mass is the thing that relates the applied acceleration (a) to the force (F) generated by this acceleration acting on the mass.

On the earth's surface, the acceleration is roughly constant at about 10 m/sec^2 (9.75... if you want to be exact). We use the letter 'g' to denote this acceleration. So, Newton's law at the surface of the earth becomes:

W = m * g

where 'W' represents the weight of the object, the *force* it would experience in the 'g' field of the earth. If we took this same mass to the moon where the value of g is about 1/6 of the earth value, W would be 1/6 of its value on earth. The mass is the same but the apparent weight is different because the acceleration is different. (This is why you see the astronauts hopping about like giddy schoolgirls in the videos from the Apollo mission.)

Force is measured in Newtons,

1 Newton = 1 kg * 1 m/sec^2

So, if I put my 1 kg of cabbage on the scale it generates a force of 1 * 10 = 10 Newtons which acts on the spring to compress it by some amount. I can label that deflection point "1 kg" but what the scale is really measuring is the 10 Newtons generated by a 1 kg cabbage in a 10 m/sec^2 force field. Take that same cabbage and scale to the moon and the needle will only deflect to read 1/6 kg. The mass hasn't changed but the force it can exert on the scale has decreased.


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## tel (May 21, 2010)

Thanks for that Marv, even this dumb ol' Aussie could follow it. I might end up knowing something yet.


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## Maryak (May 21, 2010)

Tel,

Wherever you are in the universe you will have the same mass ?lb/?kg. Your weight, (the force your mass exerts on your location), will be determined by the gravity of your location. Outer space nil, surface of the moon ~1/6 of your weight on earth, on earth your weight is ?lbf/?kgf, or, (?lb x 32 poundals/?Newtons), (at sea level), your mass remains at ?lb/?kg. All of this because Force = Mass x Acceleration. 

Mind you outer space would be a pretty grave location :

The Brits thought up poundals in 1879 but other than for the type of work that Lew undertakes, it never had common acceptance, any more than the Newton has today. Probably why we are all confused.

Best Regards
Bob


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## SAM in LA (May 21, 2010)

Seems to me that this is a consequence from the "Tower of Babel" days.

SAM


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## mklotz (May 21, 2010)

A logical measurement system should require no unit adjustment constant in the

F = m * a

equation. What that means is that 1 of whatever unit you use for mass times 1 of whatever unit you use for acceleration should equal 1 of whatever unit you use for force. This clean simplicity is built into the metric system because

1 Newton = 1 kg * 1 m/sec^2

Since a pound of force accelerates a pound of mass at about 32 ft/sec^2 (the acceleration of gravity, g), we can scale down the unit of force to compensate, giving us one that accelerates 1 pound mass at 1 ft/sec^2 (rather than at 32 ft/sec^2); and that is the poundal, which is approximately 1/32 pounds of force.

The poundal-as-force, pound-as-mass system is contrasted with an alternate system in which pounds are used as force (pounds-force), and instead, the mass unit is rescaled by a factor of 32. That is, one pound-force will accelerate one pound-mass at 32 ft/sec^2; we can scale up the unit of mass to compensate, which will be accelerated by 1 ft/sec^2 (rather than 32 ft/sec^2) given the application of one pound force; this gives us a unit of mass called the slug, which is about 32 pounds mass.

You only need to do about six kinematic problems using poundals and slugs to be instantly converted to the simplicity of the metric system's explicit separation of force and mass. (In fact, it's been so long since I used those abortions that I had to review them in Wikipedia, from which the previous two paragraphs are copied.)

Newtons may be out of favor in the engineering community but, trust me, in the physics and aerospace community they're alive and thriving.

The most important thing to take away from these discussions is the distinction between a measurement *system* and the application of that system to a field of human endeavor, e.g., engineering. If the common metric threads are ill-defined, that's an application problem, not a flaw in the metric system. Sheet metal gage numbers and numbered/letter drills are idiotic but they're not an indictment of the Imperial system. Rather, the people who established those standards didn't do their jobs well. The systems provided the means to do it right; the people failed. Far too many people who are damning metric are really upset about engineering mistakes and don't really understand what a measurement system is or what features it requires.

Also, get rid of the notion that every measured quantity has to come out to be a number between zero and 100 in your measurement system. It won't, no matter what you do - think about astronomy and cosmology or quantum mechanics. If Pascals are too small for you, use kPa or mPa (but make the relationship a power of ten) or allow your system to have derived units like the bar (100000 Pascal) that retain the original unit and a power of ten.

Then, once you appreciate these subtleties, sit down and design an imaginary measurement system of your own, keeping in mind the breadth of human activity it must encompass. When you're done, compare the salient features of your system to the metric system. I contend that your system, if done thoughtfully, will include most of the *features* of the metric system.


----------



## P.J (May 21, 2010)

The is a classic argument on the subject...

Metric vs. Imperial

or Will the USA ever go metric?

Ladies and gentlemen, we are here today to determine the United States measurement challenge once and for all.

In the blue corner we have our current US champion for many years, weighing in at 220.4623 pounds, our hero: Igor Imperial.

In the red corner we have, weighing in at 100kg all the way from France, and currently storming the world wherever he goes, our challenger: Mean Mr Metric.

It will be a great fight today and one that may change the course of history. Can Mean Mr Metric defeat Igor Imperial and change US life forever, or will Igor outwit the classy opponent and maintain his place in history.

We are about to find out.

Gentlemen, I want a clean fight. Shake hands and come out fighting on the bell.

Round 1: "DONG"

They both approach each other and meet in the middle of the ring. Metric has trained well and opens with the first punch:

How many feet in a mile?

Imperial answers after a moments hesitation with:

5280

"Good exchange there Bob, hasn't worried either of them."

"No Bill, it's still neck and neck, although Imperial took a fraction of a second to divert that question."

Imperial decides to attack with a similar strategy: How many metres in a kilometre?

Instantly, Metric flashes back with: 1000

"Wasn't that a great counter by Metric eh Bob - so quick. He's looking good tonight"

"Sure is Bill"

Imperial goes on the attack again with a curly one: How much does a litre of water weigh?

Metric comes back quickly with: 1 kilogram

"Great offense from Imperial there Bob. Combining both measurement of mass and volume - well thought out."

"Sure thing Bill, but I think he may have left himself a bit vulnerable here. If I can guess, Metric should follow up with..."

How much does a pint of water weigh?

Imperial reels back with such a tough one. He hesitates.

"Thought he'd do that Bill, he's looking shaky. I wonder how he's trained for this?"

Suddenly, Imperial's eyes light up and he comes back with:

1.0431758 pounds

"Well Bob, our champ got out of that one but it was a bit messy eh?"

"It was Bill. I think he was lucky there. Metric should come back with a tough one here if he's got it in him."

As Metric prepares for an offense, the champ Imperial slips in a sneaky one:

If 1mm of rain falls on 1 square metre of roof, how much water is collected?

"What a shot Bob! That'll hurt him."

Metric defends without a flinch:

1 litre

"No Bill, Metric has trained too well and has got too much ability. That reply was instananeous. You know, I think he should follow the same strategy as before and follow up with..."

If 1 point of rain falls on 1 square foot of roof, how much water is collected?

"Imperial is down!"

1 2 3 4 5 6 7...

7.97922 fl oz

"What an answer! Our boy's still got guts!"

"DONG"

End of Round 1.

"Bill, that bell came just at the right time. This fight shouldn't last the next round."

"You're right Bob, but that guy from France is just too good.

Round 2: "DONG"

Imperial comes out and slips in a gentle offense:

How many grams in a kilogram?

Metric defends:

1000

"Playground stuff there Bob."

"Yeah Bill"

Metric goes for the kill:

How many grains in an ounce?

"Uh oh. I think this is it Bob."

Imperial stutters:

uuuhhhhmmmmmmm. Which system?

"Oh Bill, he's answered with a question. That's not following the spirit of the game!"

Metric replies:

All three.

"Curtains Bill. I'm sure."

Imperial responds:

Well in Avoirdupois its 437.5, in Apothecary its 480 and the other one is... What other one?

Metric jabs:

You tell me.

Imperial falls to the floor.

1 2 3 4 5 6 7 8 9 10

"Knocked out Bob!"

"Yeah Bill. I guess we have to get used to the idea of a new system here in the US of A. This guy is a mean lean measuring machine."

"Just let me interrupt you Bob, our man Leroy is down in the ring talking with Mean Mr Metric."

"Mean Mr Metric that was an incredible last blow there. Tell me what is that other system"

Tell you the truth, Leroy, I don't know nor care. I just know there are three and they are all stupid.

"Interesting response there from Mean Mr Metric, Back to you Bill"

"We've just got word that the judges are going to make an announcement..."

After final discussion, the judges have decided to declare the fight null and void due to the fact that the win by Mean Mr Metric would mean that some politicians might lose the next election. 

-----------------------

for a more sobering view on the subject this might be worth a read: http://www.metric4us.com/whynot.html

Guy makes some pretty decent arguments, banging the drum a bit too much... but meh, whatchagonnado.

Love from Sweden,
/P.J


----------



## ianjkirby (May 22, 2010)

mklotz  said:
			
		

> As a challenge, sit down and design your own ideal measurement system - not a system of engineering standards but a generally useful measurement system.



A few years back, one of my Uni professors challenged us to derive a totally "new" system of units, wherein mass was defined as the mass of the earth, distance was defined as the distance from the earth to the sun, and time was defined as the period of the earth's rotation around the sun. Among other things, we had to recalculate our body mass in these terms, the average fuel in terms of the economy of a common car, and a new definition of "g", the universal gravitational constant. It certainly put my views of "standards" in perspective!!
Regards, Ian.


----------



## Lew_Merrick_PE (May 22, 2010)

mklotz  said:
			
		

> A logical measurement system should require no unit adjustment constant in the
> 
> F = m * a
> 
> ...


Marv,

The unit of acceleration in most *applications* is the Earth's gravity (g). Thus, 1 lbf = 1 lbm * 1 g. 1 lbm is what *used* to be called the _poundal_ -- a nomenclature that disappeared from common usage in the mid-1970's. If the designation _lb_ is used without comment, it is a *force*. The mass designation should *always* be _lbm_. I admit that *I* tend to use _lbf_ and _lbm_ when I write technical papers as it reduces possible confusion.

The *standards* for metric measure designate the use of a leading zero (0) when the absolute value of the number is less than one. Similarly, no trailing zeros are allowed in metric measure according to the standards. The standard for the inch-pound-second system is that no leading zero will be used and that trailing zeros are applied to designate the level of resolution (usually applied in practice as the default tolerance) of the value. I received a drawing set from a German company wherein they use trailing zeros to designate default tolerances in direct contravention of the ISO standards. They *also* designate the _kgf_ as *the* unit of force and _kgf-cm_ as *the* unit of torque. This has been increasingly common over the past three decades as the metric system tried to "catch up" with the inch-pound-second system.

If the schedule is not changed, there is a Mars lander being launched this coming August. The fuel pump for the vector thrusters that will steer it from here to Mars is one I designed and developed. The *entire* acceleration profile for the mission is laid out in g's -- not m/s², cm/s², in ft/s², or in/s². The feedrate for the hypergolic fuels is calculated in moles/s. I regularly design things for orbital usage and I can assure you that the dimensions that control such "missions" are *neither* metric nor inch-based. In point of fact, *Newtons* are now a "non-preferred" unit of force for space applications *because* of the Mars Polar Lander debacle.


----------



## Maryak (May 22, 2010)

Lew_Merrick_PE  said:
			
		

> The unit of acceleration in most *applications* is the Earth's gravity (g). Thus, 1 lbf = 1 lbm * 1 g. 1 lbm is what *used* to be called the _poundal_ -- a nomenclature that disappeared from common usage in the mid-1970's.



Pardon my ignorance but a poundal is a unit of force - well at least according to the Oxford dictionary.

Best Regards
Bob


----------



## New_Guy (May 23, 2010)

reminds me of a talk i had with my girl friend who said another friend told her, her boy friend had something 16" long...... ill let you guys guess but its not his feet  lol she wouldn't let me explain just how long 16" really is 

great story thanks for telling now i what i want to know is why you guys leave the U out of Colour ;D


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## Deanofid (May 23, 2010)

New_Guy  said:
			
		

> reminds me of a talk i had with my girl friend who said another friend told her, her boy friend had something 16" long...... ill let you guys guess but its not his feet  lol she wouldn't let me explain just how long 16" really is
> 
> great story thanks for telling now i what i want to know is why you guys leave the U out of Colour ;D



No clue to what you're talking about, but we leave the U out of Color for the same reason we leave the R out of Idea and Washington. They don't belong there!

DW


----------



## tel (May 23, 2010)

Well Idea and Washington have never had an R, but colour has always had a U. But then, you blokes spell _plough_ as _plow_ and _cheque_ as _check_- go figure???


----------



## Maryak (May 23, 2010)

I can see the logic in sulfur rather than sulphur, color instead of colour, harbor instead of harbour, but why not fotograf instead of photograph, graf instead of graph, etc.

Our common language can't seem to shake its' foreign influences whichever side of the big ponds we are, (by the way the forum spell checker/chequer is having a field day).

Best Regards
Bob


----------



## kcmillin (May 23, 2010)

When you look in the English dictionary, there are two words for every word. One is the original, and the second is how it should be pronounced. Why then, don't we just write every word how it is pronounced, that would eliminate any confusion. Except for accent that is, not sure how to wright down a British, or Australian accent. We all speak the same language, but is a slightly different way. 

Kel


PS. A side question.  My high school English teacher told me that the word "Root" is a bad word in Australia, and "Root Beer" is called "Sweet Beer". Is this true? If it is, I apologise for writing it down.


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## potman (May 23, 2010)

It's a warm afternoon and you and I are sitting in
the back yard pouring down a few brews when the
discussion turns to measurement systems. We both
grouse about the fact that none of the existing systems 
are ideal and decide that we will create a better one.

After some discussions about what would be the best
length to use the beer gets to us and we take a hike
into the woods to find a bush to water. As we are 
standing there we both notice a stick laying on the
ground and quickly agree that it is the perfect length
for our new standard. We pick up the stick and go
back to ponder it and have another brew.

Quickly the discussion turns to how do we define 
measurements shorter than 1s ( one stick ). Do we
use 1/2, 1/3, 1/10 of a stick, or what. Being the 
compromising fellows we are, after a few more brews 
and a few more bush waterings, we reach an agreement;
the shorter measurement will be called "part-o-stick".
Happy as hogs-in-a-mud-wallow we clink our mugs and
consider the day well spent.

Now all we have to do is convince only
*6,822,744,064*  other people 
that our brilliant work should be the world standard.
Piece of cake !

So, y'all want to come over and have a beer this
afternoon? We have an idea to talk over with you.

Earl...


----------



## Lew_Merrick_PE (May 23, 2010)

Maryak  said:
			
		

> Pardon my ignorance but a poundal is a unit of force - well at least according to the Oxford dictionary.


Bob,

The Poundal is the old name for "Pound-mass" (abbreviated as lbm). It is the mass that, when accelerated by 1 g, generates one pound of force -- definition from McNeese and Hoag _Engineering & Technical Handbook_ (1957).


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## mklotz (May 23, 2010)

Wiktionary...

(dated) (physics) A unit equal to the force needed to accelerate a mass of one pound at a rate of one foot per second per second.

Wikipedia...

The poundal is a unit of force that is part of the foot-pound-second system of units, a coherent subsystem of English units introduced in 1879, and one of several specialized subsystems of mechanical units used as aids in calculations. It is defined as 1 lb·ft·s-2, or in words, as the force necessary to accelerate a pound of mass at 1 foot per second, per second. 1 pdl = 0.138254954376 N exactly.

Free Dictionary...

A unit of force in the foot-pound-second system of measurement, equal to the force required to accelerate a standard one-pound mass one foot per second per second (approximately 0.138 newton).

Merriam-Webster...

 a unit of force equal to the force that would give a free mass of one pound an acceleration of one foot per second per second

Your Dictionary...

the basic unit of force in the FPS system, equal to the force which imparts an acceleration of one foot per second per second to a mass of one pound (0.1383 newton or 13,825.5 dynes): abbrev. pdl


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## Deanofid (May 23, 2010)

tel  said:
			
		

> Well Idea and Washington have never had an R, but colour has always had a U. But then, you blokes spell _plough_ as _plow_ and _cheque_ as _check_- go figure???



Kind of my point there, Tel.  I was poking fun at some of my countrymen who say "ideer" and "Warshington". 
We have enough words with letters we don't vocalize. No need to add more that were never there!


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## mklotz (May 23, 2010)

All those extra 'r's in the Northwest are just a manifestation of the natural law of the conservation of consonants.

They're there to balance all the missing 'r's in the cahs and pahks in the neighborhood around Havahd Yahd.


----------



## black85vette (May 23, 2010)

mklotz  said:
			
		

> All those extra 'r's in the Northwest are just a manifestation of the natural law of the conservation of consonants.
> 
> They're there to balance all the missing 'r's in the cahs and pahks in the neighborhood around Havahd Yahd.



Never thought of it that way.  So in a sense we keep the forces of nature balanced by keeping extra R's in one part of the universe to balance out the lack of them in another?? Not sure that works out mathematically. But should we use metric or imperial when doing that calculation?


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## arnoldb (May 23, 2010)

Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof} Rof}

I wasn't about to get into the annual metric/imperial debate (I use whatever is convenient), and I steer away from linguistics as well, but Dean and Marv's posts made me ROTFLMAO - even the parrot's laughing Rof} Rof} Rof} Rof} Rof}

 Rof} Rof} Rof} Rof}
Arnold

B85V: 1.27 R's, 1.27 L's (go figure ) to one part H's and all should be good to go :big: - You posted while I was busy....


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## mklotz (May 23, 2010)

It's not just the consonants that need to be conserved and dispersed uniformly. Imbalances in the vowel-force threaten tongue muscles across the globe.

We Americans are ever responsive to such crises and eager to help wherever we can. Even as I write, an emergency shipment of vowels is being prepared and will be sent to Wales, and the Welsh will be trained in the use of them. The town of Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch will be renamed "Waialea" to restore the alphabetic balance in the UK.


----------



## cidrontmg (May 23, 2010)

Just a wee bit more about the original topic. I know that 1 inch is nowadays (since1959) 25.4 mm exactly. My lathe (at least the "industrial stand" it sits on)
was made before that, I think. 
Sorry about the pic quality, but I guess you see what I mean. When this Myford Super 7 (the stand) was made, inches were shorter. Maybe that´s the reason why I often turn inaccurate work ;D


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## Daniel (May 29, 2010)

kcmillin  said:
			
		

> Some Comedy from a friendly family debate, based on a true story. And proof, that I win every debate that I enter. This is not meant to affend anyone, and is only the thinking of one person, but worth a read.
> 
> 
> The Great Metric System Debate
> ==============================



By the same token a similar discussion could result with a different outcome:


ME = My Brother. And Her = My Neice


HER: Dad, I need money for a haircut


ME: Why do you need a haircut?


HER: I need to take a few centimeters off the back


ME: Centimeters? - Who the hell is teaching you to use centimeters to measure your hair. Liberal teachers are infiltrating and taking over our entire education system.


HER: Dad, centimeters are small, and I just need a LITTLE off


ME: You mean 1/2 Inch


HER: No - a few centimeters


ME: Yeah - try asking your stylist to take off a few centimeters, and she will look at you like you are a crazy French woman


HER: What are you talking about


ME: The French - they invented the flawed way of measuring things now known as the "Metric System"


HER: Everyone uses the metric system, except for us... Maybe we are the ones with the flawed system


ME: WHAT! - Nothing American is flawed, including our system of measurement, plus, we aren't the only ones, I am pretty sure Liberia uses our system.


HER: Actually, no. People who have traveled to Liberia have found the metric system in use. Your information must be as out dated as American measuring units.


ME: Who cares about Liberia anyway! Don't you see, our system is far superior. Who knows what a centimeter, or meter or kilometer actually is? - I sure don't. But I do know what an inch is, a foot, a yard and a mile. All of them perfect. 12 inches in a foot, 3 feet in a yard, 5280 feet in a mile. It all makes perfect sense. And we can get small too... half-inch, quarter-inch, eighth-inch, sixteenth-inch - you see, never ending, and easy to remember. Don't even get me started on Rods, Fathom's and Leagues. 


HER: Who knows what a centimetre, metre or kilometre are? Everyone in the world does? Just because you are ignorant doesn't mean everyone else else. If your choice of outdated units was so wonderful everybody would be using them and you wouldn't be so angry because that makes you a minority.


ME: Are you calling me ignorant?


HER: umm...yes....if the shoe fits wear it! Your system is complex and the metric system is easy. Easy means less cost and fewer mistakes


ME: See what I am saying? - "Easy" equals "Lazy" equals a well thought out plan by the French to take over the world and make us all have 35 hour work weeks and 28 paid holidays a year.


HER: Sounds good to me. You seem to have a hang-up about the French, why are you so jealous of their success? And it isn't just the French who use it and are prospering because of it. The whole world is. Easy doesn't equal lazy, easy equals efficient. Your outdated units make for a lot of inefficiency.


ME: And furthermore, the Metric system is based on an incorrect measurement of the circumference of the earth...The guy that tried to figure it out, screwed up, but was afraid to tell the king of France. So now, the entire Metric system is based on an incorrect measurement. Imagine if we started using it, everything that we measure would be WRONG!! We'd have crooked houses, and leaning buildings - thank God for Feet and Inches


HER: Are you kidding me...really?....Boy when you are wrong and know you are wrong you sure come up with a crock of crap. Does it matter how it was made? - no.... What matters is that today the metre is accurately defined via the speed of light and even you beloved outdated units are defined from the metre. They are parasites having to cling to the metre for meaning.


ME: How dare you call my beloved units parasites! They are time honoured.


HER: Oh my God


ME: Do you really want the French to take over? - Look what they did to Quebec


HER: The French are not going to take over. But the Europeans and Asians because they use the metric system have taken all of our industrial jobs. What was once made in inches in the US is now made in metric elsewhere. Even your American cars are metric. I'll bet you didn't know that.


ME: To prove my point, do you know how many Kilometers is it from Bismarck, ND to Eugene, Oregon?


HER: I have no idea


ME: Exactly, nobody knows kilometers, because in America, we use Miles


HER: Ok then, do you even know how many "Miles" it is to Eugene, Oregen?


ME: Of course I do.


HER: Obviously you don't


ME: Ok - Fine, I have 2 words for you: "Mars Polar Lander"


HER: What...


ME: "Mars Polar Lander"


HER: That's 3 words


ME: Maybe so, but those 3 words represent a spaceship, that CRASHED into the surface of mars, instead of gently "LANDING" - Do you know why?


HER: Please tell me


ME: The Metric System


HER: Dad...Shut up


ME: It's true, some idiot put into the computer measurements in Meters instead of Feet....And what happened? - It Crashed. If not for the Metric system, the Mars Polar Lander, would have actually landed, but no, the French sent us the "Mars Polar Crasher" instead


HER: What a load of crap. The Mars Polar Lander crashed because NASA did use the metric system and a sub-contractor didn't, even though the contract required it. It was the use of outdated units that caused the crash. 


ME: Ok smarty pants, do YOU know how many Meters it is from Mars Orbit to the surface of Mars? - I don't think so.


HER: When you argue with me, you just make stuff up to support an opinion that you obviously know is wrong but you are afraid to admit. Dad, just admit it, I'm right, you're wrong, Metric system is better.


ME: Not according to the NFL I'm not


HER: I don't care


ME: Yeah, well, Tony Dorsett sure cares. He still holds the longest Rushing Touchdown record at 99 yards. Are you telling me that you want Tony Dorsett to be stripped of his record in the Record Books? Or worse, have his record written as "90.5256 Meters" - Doesn't really roll off the tongue now does it?? Not only that, but what would you have the Indy 500 renamed to? - "The Indy 804.672"? - I am sure drivers and spectators would flock from Miles (er. Kilometers) around to witness the Historical Tradition of the Annual Indy 804.672.


HER: Only a user of outdated units would come up with crap like you do. Tony Dorsett's record would be 90 m when rounded to sensible numbers and the Indy 500 could be extended to 1000 km and be called the Indy 1000. Please keep away from my friends, your total lack of intelligence would be a great embarrassment to me. 


ME: Well, I won the argument anyway because I said so.


HER: Because I Won, a looong-time-ago


ME: Communists use the Metric system you know. Apparently that is what you want for us, to live under the harsh oppressive rule of a communist dictatorship. How many square METERS of land do you own? - NONE - because the government owns it and has stripped you of your private property, and convinced you that they know best leaving you a sad and dependent soul who knows not the joy of owning your own 10 acre parcel of land. Thank you honey, for ruining our country and everything we believe in.


...


HER: communists? What century are you living in? Communism died decades ago. Even the Chinese who have the fastest growing economy in the world have a capitalistic economy. They are making all of our products in metric.


ME: Yeah


HER: I still need a haircut


ME: Why


HER: I need to take a centimetre off the back.

ME: Well, I can't give you any money. I lost my job when I refused to go along with the company's decision to metricate. I'm now blacklisted and will never get a decent job again. But, you know what? I'd rather be broke and homeless then have to use the metric system.

HER: Sooner then you think. 

[/quote]


----------



## Daniel (May 29, 2010)

Maryak  said:
			
		

> = 236/64 = 3 11/16 ??? or 93.66233775



This is exactly where the conflict comes into play. When you choose a set of units to work with, you gravitate towards sensible rounded numbers. Sensible rounded numbers in one unit don't translate to sensible rounded numbers in another unit.

To those of us who work in the metric system, the number 93.66233775 is meaningless. We would round it to 94 mm. However, this may present a problem if a part made to 3 11/16 inches and 94 mm don't fit together.

Since the whole world is now metric and the fastest growing industries use only the metric system, this presents a numbers problem with those who still cling to obsolete inch based sizes. 

Jobs are fleeing the US, especially those jobs where products are made to measurements. Products once made in inches in the US have been metricated and are now made in metric units elsewhere. I guess Americans would prefer to be unemployed or working for slave wages than use the metric system and be prosperous. America's loss is the world's gain. 

BTW, if I multiply 3.6875 by 25.4 I get 99.6625. Where did you get 93.66233775?


----------



## Daniel (May 29, 2010)

kf2qd  said:
			
		

> Hey man - Metric is great - IF you grew up your whole life using it. Otherwise it is a royal pain in the.. whatever. I understand metric, but it is just too much bother to convert to a system that I have never had to use and in reallity offers no real benefits. One can measure just as accurately in either system. It is also easier to divide thins in half, as we do for all the franctions - 1/2, 1/4, 1/8, 1/16, 1/32, 1/64 than it will ever be to divide things by 10. (Fold this paper into 10 equal parts...)
> 
> And we all know that the "standard meter" myth (that is is some portion of the distance from the north pole to the equator) was just an attempt by the French to try to justify a system that was really based on dividing the inch into 25.4 sections because they screwed up and failed to divide the inch in 25 segments. Then the Milimeter and the Meter would both have made sense.(25 millimeters to the inch and 40 inches to the meter) But because some Frenchman used some poorly made (Non-Starret, non-Mitutoyo) tools to measure out his NON-INCH millimeter those who use the millimeter have to put up with odd dimensions. And it is interresting that they try to this day to blame it all on the Americans when it was really just the result of some tizzy between the British and French going back who knows how far. The British have made a feeble attempt to placate the French (the british are europeans after all...) but what with stones and other silly units of measure they have still managed to stick it to the French. So the last bastion of sense and reason is the U. S. of A. who still have enough brass to uphold the noble, sensible and reasonable INCH, FOOT, and YARD as the only proper units of measure.



Wow! Is this the type of thinking that comes from the American educational system? But why am I not surprised? There was never an attempt by the French or anyone else to divide the meter in any parts other than multiples and sub-multiples of 10. The inch of 25.4 mm did not exist until 1960. Before that the inch kept changing in length every few years. Every country, state, province, city, town and village had their own size of inches. Which one was the right one? Was there ever a right one? The "pouce" was the name used for inch in France. At the time of the introduction of the metric system, the pouce used in Paris was equal to 27.07 mm, thus 1.67 mm longer then the American inch post 1960. 

Can you ever trust a unit that can't stay constant?


----------



## Daniel (May 29, 2010)

rake60  said:
			
		

> Anthony *THAT* is a *PERFECT* answer! :bow: :bow: :bow:
> 
> A size is a size. It doesn't matter if it is in tenths of a centimeter or thirty secondths of an inch.
> Either way you will hit it or miss it.
> ...



It matters to the person when a round number in metric doesn't come out as a round number in obsolete units. If I need a hole drilled that must be 50.00 mm +/-0.01 in diameter and the same dimension is 1.968 503 937 inches, are you going to tell me that such a number is acceptable in inch units? It isn't. People who insist on using obsolete units want the numbers to be round. But if you try to round a highly precise metric dimension in inches, it will no longer be precise in metric and the hole will end up being the wrong diameter and the part will be rejected.


----------



## Daniel (May 29, 2010)

Lew_Merrick_PE  said:
			
		

> Marv, Until you've watched French, German, and Japanese engineers scrambling across 5 acres of land looking for the pieces from their inflator that failed because they misread the powers of 10 in their Pascal calculations, you don't know just how "good" the metric system is. Why is it that so many "metric countries" have changed from N-m to kGf-cm for torque? Have you ever tried to apply an M10 (X1.5) screw to a cast aluminum part?
> 
> These all indicate that the "mesh" of Newton-derived units is pretty poor. It can be truly funny to look at the rework budget for companies that have gone "all metric" as they fail to realize that there are *still* five different and incompatible standards for tolerance and allowance with respect to metric screwthreads. I have lived through three fairly major _adjustments_ to basic units of the metric system -- it is still a _work in progress_ at best.



Obviously Lew's story here is complete fiction by a person disgruntled because he has shown himself to be obsolete in a metric world. What I see is a world that increasingly buys German, Japanese, Italian, Chinese and products designed, engineered, manufactured and serviced in metric units and decreasingly buys American products made in obsolete units.

I use metric fasteners all of the time and never had a problem with them. I would also say that the American Automobile and heavy machine industries that still exist will disagree with you. They are fully metric and function perfectly well with it. The only times problems are encountered is when some has been tries to introduce obsolete units into the equation resulting in errors

Maybe it is time for Lew to come into the real world and depart from his fantasy world where USC is wonderful and metric is tragic. Maybe if USC was so wonderful, business after business would not be fleeing the US for the metric countries and instead the world's manufacturing would be moving to the US to take advantage of the wonderful world of USC. The fact that industry is leaving the US proves that USC and those that support it suck.

Germany didn't become the world's largest exporter by using inches.


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## cidrontmg (May 29, 2010)

"BTW, if I multiply 3.6875 by 25.4 I get 99.6625. Where did you get 93.66233775?"

Hm. I don´t, but this IS a chinese calculator. 3.6875 x 25.4 seems in this technical marvel to be 93.6625...


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## Maryak (May 29, 2010)

Daniel  said:
			
		

> BTW, if I multiply 3.6875 by 25.4 I get 99.6625. Where did you get 93.66233775?



25.4 mm = 1 inch is a convenience number decreed by ISO in 1959 much like the US declared 39.34" = 1 metre. The various experiments to actually measure one against the other gave results varying from - 25.399978, 25. 399956, 25.400051 mm/inch. I chose the middle one to get the above. Who knows what the actual of one to the other is, and who cares. 25.4 works for me. This debate has kinda gone from the sublime to the ridiculous and I felt left out. :

Best Regards
Bob


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## shred (May 29, 2010)

What's funny is most 'designs' care not one whit about the system they are measured in these days.

Take, say, an item probably everyone on here has within 4 feet of them. Tens of millions manufactured every year. The humble computer mouse.

Know how the cord length on a standard USB mouse was determined? A "designer" dragged a piece of cord across a couple raised floor tiles, picked it up and said "about that long".  Saw it first-hand.


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## Lew_Merrick_PE (May 29, 2010)

Daniel  said:
			
		

> Obviously Lew's story here is complete fiction by a person disgruntled because he has shown himself to be obsolete in a metric world. What I see is a world that increasingly buys German, Japanese, Italian, Chinese and products designed, engineered, manufactured and serviced in metric units and decreasingly buys American products made in obsolete units.


Sorry Daniel, it's true. Less than two years ago I "solved" an assembly problem at a major marketer of consumer electronics by pointing out that their German supplied screws were being assembled into Chinese supplied nuts. If you dig through the complete set of ISO screwthread tolerances & allowances, you will find that there is a different set of tolerances & allowances -- Germany uses the DIN derived set and China uses the JIC derived set. In large-scale manufacture, you have a 43% chance that the two will not assemble correctly. The "fix" was relatively simple -- _specify the controlling tolerance and allowance standard on the drawings_!

I use all sorts of units of measure. As I noted at the beginning of this diatribe set, I lived in a metric world until just before my tenth birthday. I was frustrated trying to learn traditional American measure. As I lived in an area dependent on pulp & paper, we still used 1/128th's of in inch. Yeah, tell me about it. When I work in optics, we typically use 240 nm as the unit of measure (1/4 wave of standard IR emitters). When I work in nuclear operations, we typically use the "shake" (about 20 cm -- the distance light travels in 1 ns). When I am designing manufacturing lines, I like to use the "stone" because of its historical significance. Etc.

My "complaint" with the metric system is two-fold. The Newton, and units derived from it, have an extremely poor "mesh" that leads people -- even those who have *never* used anything but metric measure -- to make mistakes. The other is that the metric system of screwthreads is really poorly thought out and applied. Yes, it has been (just barely) more than a decade since "regional" threads were removed from the ISO standards. That does fix a lot, but until the allowances and tolerances are unified, it is *still* problematic. More importantly from *my* side of the street, the ability to tailor a screwthread to the material being used for the design is nowhere *near* as well considered as those offered by the UN thread series.

My "observation" is that the metric system itself is being "rejected" by countries and companies when it comes to the Newton. Most of the JIC-derived metric world uses the *kgf-cm* measure for torque. I first saw that applied when (as noted above) I ordered _metric torque wrenches_ from *France* for a NASA project (though those were "calibrated" in _kgf-m_). If you want a mess on your hands, write up a torque specification in N-m on a drawing for something that will be assembled in China! They (most Chinese manufacturers) have less of a problem with _lb-in_ or _lb-ft_.

I have done work for more than 350 companies and government agencies across five continents. If you have an airbag restraint system in your car, there is a 30% chance that it is one of the units *I* developed and qualified. That is where *I* am "coming from" here.


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## Maryak (May 29, 2010)

OK,

We have just proven that the unsolvable is unsolvable. Going round in ever decreasing circles we end up you know where, doing you know what. 

Before we reach that point I am locking this thread so we can all get back to making models to the measurement system of our choice.

Best Regards
Bob


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