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METRIC ! 52
- Thread starter ceesjan
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Has anyone given any thought to the cost to replace measurment instuments and such, most of which must be provided by the machinist. While I agree that it is easier for engineering to use metric, this is not true for manufacturing. I didn't whine when metrics was implemented and I had to convert them to decimal, why must it be your way.
JML has pointed out that "The Metric System is a modern system devised to be a coherent system of units." There was an interesting documentary about the two French gentlemen who set out to define the meter as a fraction of sector of the earth. Unfortunately one got caught up in a war and got stuck at the latitude (I think in Spain) for the South extremity of the sector. Being the good scientist that he was he took advantage of the delay and repeated his thousands of readings, to verify his initial findings. Unfortunately he got a different answer so he did not tell anyone about the problem. I think he just used the second set. Subsequent analysis has determined that that the error was due to wear and tear on his much used instrument. So we are stuck with yet another irrational basis for a unit of measure. Does it really matter? It turns out the earth is not as round as they thought it was then anyway.
I am sure others have further information on this piece of science history. I will be interested to see any additional postings which can correct/expand my recollections. HAZOP at
I am sure others have further information on this piece of science history. I will be interested to see any additional postings which can correct/expand my recollections. HAZOP at
Don't worry about the cost of the instruments to measure, what about all of the automated machines that are driven by imperial and their operators. It is logistically easier to teach technical people to convert units than it is to teach the ordinary person to convert units.
Although I grew up in an Australia that was converting to metric (DOB 1965) I am still amazed to see older people using imperial as their terms of measure (quite often converting from metric first!!). The real transition took about ten years of education via the education system as I can recall many teachers who simply refused to teach just the metric system. So I am lucky that I can now rapidly convert the basic units in my head.
The SI system is still the way to go but again not every one talks the same dialect. Here is a recent example of units that were available in an analysis program: kN/m^2, N/m^2, kN/cm^2, N/mm^2, kPa, Pa, plus three versions of imperial measure. The SI system as I understood it is designed to simplify measure to units of 10, with a means of reducing the number of numbers dealt with, ie: k for 1000, M for 1000000, etc. Why doesn't it seem to work in practice?
regards
sc
Although I grew up in an Australia that was converting to metric (DOB 1965) I am still amazed to see older people using imperial as their terms of measure (quite often converting from metric first!!). The real transition took about ten years of education via the education system as I can recall many teachers who simply refused to teach just the metric system. So I am lucky that I can now rapidly convert the basic units in my head.
The SI system is still the way to go but again not every one talks the same dialect. Here is a recent example of units that were available in an analysis program: kN/m^2, N/m^2, kN/cm^2, N/mm^2, kPa, Pa, plus three versions of imperial measure. The SI system as I understood it is designed to simplify measure to units of 10, with a means of reducing the number of numbers dealt with, ie: k for 1000, M for 1000000, etc. Why doesn't it seem to work in practice?
regards
sc
sc - Why don't we make better use of deca, kilo, mega, and their cousins deci, centi, milli, nano, pico, femto, atto, giga, tera, peta, exa? Perhaps it is because they are far from being a modern coherent set. Rather they are tributes to "the Latin", and a few recent heroes of science. Presumably they were named to avoid favouring either the English or the French language. At the time many of us studied Latin so that was a good choice. Its time to rename them based on ten hundred, thousand, million, billion, trillion, etc. Then perhaps we will stop selling cars with 200,000 km on them, and my doctor will stop prescribing 1000 mg pills.
As an old fuddy-duddy who will be dying out soon, I just thought a final outburst might make my 86,400 second day. HAZOP at
As an old fuddy-duddy who will be dying out soon, I just thought a final outburst might make my 86,400 second day. HAZOP at
The metric system is for lazy people who would rather shift a decimal point that learn to multiply or divide by 12 or 3 or 4 or 8 or 16 or or or or... ![[2thumbsup]](/data/assets/smilies/2thumbsup.gif "[2thumbsup] [2thumbsup]")
Just kidding.
as an american, I learned the imperial (suitably modified) measurement system, but having travled and worked in many other areas of the world, I had to learn the SI system. Big Deal!
I don't convert. 20 C is 20 C. 32 F is still 32F. I do find that a meter is too long and a gram is too small.
I find that engineers were smart to do away with inches and divide the foot into 10th's
Architects should do the same thing instead of foisting fractions on us.
to paraphrase archemedes... "Give me a stick and I can measure the world." I just have to hand THE stick to you so you can verify my measurements.
In other words, give me a system. Tell me the rules. Then YOU stick to the system and the rules YOU gave me. (and hurry, please.) :-D
Just kidding.as an american, I learned the imperial (suitably modified) measurement system, but having travled and worked in many other areas of the world, I had to learn the SI system. Big Deal!
I don't convert. 20 C is 20 C. 32 F is still 32F. I do find that a meter is too long and a gram is too small.
I find that engineers were smart to do away with inches and divide the foot into 10th's
Architects should do the same thing instead of foisting fractions on us.
to paraphrase archemedes... "Give me a stick and I can measure the world." I just have to hand THE stick to you so you can verify my measurements.
In other words, give me a system. Tell me the rules. Then YOU stick to the system and the rules YOU gave me. (and hurry, please.) :-D
the thing that annoys me most, to refer back to a post from a fair way up the thread, is that "1 cubic meter of water weighs 1000 Kg"... that's the absolute stupidest thing about the metric system. now don't get me wrong, i'm a metric man all the way and think imperial systems are just a great invitation to screw up, but why is it that the metric measure of mass's base is a factor of a thousand out from the rest of it's units?
a cubic metre should weigh a gram... that way, ONE newton would accelerate ONE gram by ONE metre per ONE second!
WHY OH WHY is a gram one thousandth of the mass it should truly represent!??
now that i've ranted about my one major problem with SI units, i can start on my 59 major problems with imperial units...
col.
a cubic metre should weigh a gram... that way, ONE newton would accelerate ONE gram by ONE metre per ONE second!
WHY OH WHY is a gram one thousandth of the mass it should truly represent!??
now that i've ranted about my one major problem with SI units, i can start on my 59 major problems with imperial units...
col.
Why not 1 mega gram. Isn't the SI system supposed to allow us to work in small numbers. HAZOP at
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GregLocock
Automotive
Yes....
Cheers
Greg Locock
Cheers
Greg Locock
autocol is correct and I just wanted to post to support him, and Homer of course, Homer is never wrong!!! I think Homer is a closet Engineer, Nuclear of course, now we know why nucler engineers are a little bit stranger than the rest of us!!!
BobPE
BobPE
Sorry guys I don't watch the Simpsons at all since my wife caught my oldest daughter and I discussing the more stressful (for Bart and Homer) parts of a particular Simpsons episode and how it could be applied to her mum every now and then. So now it is banned whenever she is in the house.
sc
sc
owg,
The meter is no longer defined by the original measurements taken by the originators of SI, it's now defined by the length of a certain (Not very round) number of wavelengths of a particular emission wave for a particular atom (Haven't time to check out the specifics at the moment).
The same is true for the mass of the kilogram, the length of the second etc. They're all defined by atomic physics rather than the older more direct standards (IIRC the length of a metre and the mass of a kg used to be defined by the length of platinum bars held under atmospheric and temperature controlled conditions in France).
I would be interested in finding out why the kg is the fundamental unit of mass instead of the gram or rather why the gram wasn't assigned a mass equal to a kg first day. It could be due to chemistry calculations where 12g of Carbon 12 is equal to 1 mol of the substance, but I wonder does anyone else know.
Also, speed limits in Ireland are still posted in mph, with distances in miles on old signs and km or miles on new ones (Since people are happy enough working with either unit it doesn't really matter). Green signs are always km though. Temperature is always in Celcius, celcius is about the only unit in SI that really is easy to get your head around, 0 is where water freezes and 100 is where it boils. I've never used farenheit at all, though medical thermometers often use it.
I've worked in SI and Imperial/US units, and SI certainly makes more sense. Ireland still uses a mix of units, but the SI system almost universal for industry, except for the specification of wire gauges, pipe fittings and land areas.
Strangely enough I'll still give distances in inches/feet when talking to people but always work in m/mm on paper. Part of teaching people to work in SI does involve assigning every quantity in the calculation a unit and performing the calculations on both the numbers and the units to arrive at an answer. If this answer has the correct units then at least the form of the equation used is correct. The lack of fiddle factors in calculations is the real strength of SI I think.
The meter is no longer defined by the original measurements taken by the originators of SI, it's now defined by the length of a certain (Not very round) number of wavelengths of a particular emission wave for a particular atom (Haven't time to check out the specifics at the moment).
The same is true for the mass of the kilogram, the length of the second etc. They're all defined by atomic physics rather than the older more direct standards (IIRC the length of a metre and the mass of a kg used to be defined by the length of platinum bars held under atmospheric and temperature controlled conditions in France).
I would be interested in finding out why the kg is the fundamental unit of mass instead of the gram or rather why the gram wasn't assigned a mass equal to a kg first day. It could be due to chemistry calculations where 12g of Carbon 12 is equal to 1 mol of the substance, but I wonder does anyone else know.
Also, speed limits in Ireland are still posted in mph, with distances in miles on old signs and km or miles on new ones (Since people are happy enough working with either unit it doesn't really matter). Green signs are always km though. Temperature is always in Celcius, celcius is about the only unit in SI that really is easy to get your head around, 0 is where water freezes and 100 is where it boils. I've never used farenheit at all, though medical thermometers often use it.
I've worked in SI and Imperial/US units, and SI certainly makes more sense. Ireland still uses a mix of units, but the SI system almost universal for industry, except for the specification of wire gauges, pipe fittings and land areas.
Strangely enough I'll still give distances in inches/feet when talking to people but always work in m/mm on paper. Part of teaching people to work in SI does involve assigning every quantity in the calculation a unit and performing the calculations on both the numbers and the units to arrive at an answer. If this answer has the correct units then at least the form of the equation used is correct. The lack of fiddle factors in calculations is the real strength of SI I think.
peglor - Thanks for pointing out the current bases for SI standards. I think that the reason that the number of wavelengths is "not very round" is that it is chosen to equal the originally floored measurement. Perhaps we should have waited until the earth changed shape enough, then repeated the measurements when the wavelength number came out to be a whole number. The length of a king's foot still makes more sense to me on a cost/benefit basis.
HAZOP at
HAZOP at
I believe that the real reason the USA resists conversion to metric is the manufacturing and business infra-structure.
Machine tools are calibrated in English units.
Pre-formatted programs assume English unit values. For example, to make an entry in a catalog, I might enter the number 51. The output automaticvally appends "inches" or some other unit to that number. And, so forth.
The education component can be dealt with over time. The replacement of machines and programs, etc. can also occur over time but the result would be some machines on a shop floor producing in metrics and others in English units. That is patently intolerable. A means of cost-effectively managing the transition has not been devised.
Even if you consider a "green-field" plant, the transition is a problem. If there is no market for metric widgets, then it makes no sense to make them.
So, in my view, economics is the problem; not education or arrogance or willfulness or the lack thereof.
If there was an economical solution, I am sure American businessmen would be pursuing it aggressively.
Machine tools are calibrated in English units.
Pre-formatted programs assume English unit values. For example, to make an entry in a catalog, I might enter the number 51. The output automaticvally appends "inches" or some other unit to that number. And, so forth.
The education component can be dealt with over time. The replacement of machines and programs, etc. can also occur over time but the result would be some machines on a shop floor producing in metrics and others in English units. That is patently intolerable. A means of cost-effectively managing the transition has not been devised.
Even if you consider a "green-field" plant, the transition is a problem. If there is no market for metric widgets, then it makes no sense to make them.
So, in my view, economics is the problem; not education or arrogance or willfulness or the lack thereof.
If there was an economical solution, I am sure American businessmen would be pursuing it aggressively.
I've heard rumor that the metric system was the brain child of Napolean (although not French himself) and the US will never completely go metric because of it's (French) origin -- ha, ha...
anyway, it is a shame that our schools do not teach the metric system anymore than it does -- the fundamentals of understanding measuring systems really originate at home to kids before they even go to school -- we will need to have the parents comfortable in doing things normally in the metric system so the future generations will have an inate feel for it (I fully understand the system, but it is not intuitive to my thought process)... I specify all things in US Standard because all of my employees know it and few know the metric system... a ½" is obvious, 15 mm is an unknown...
anyway, it is a shame that our schools do not teach the metric system anymore than it does -- the fundamentals of understanding measuring systems really originate at home to kids before they even go to school -- we will need to have the parents comfortable in doing things normally in the metric system so the future generations will have an inate feel for it (I fully understand the system, but it is not intuitive to my thought process)... I specify all things in US Standard because all of my employees know it and few know the metric system... a ½" is obvious, 15 mm is an unknown...
GregLocock
Automotive
"US will never completely go metric because of it's (French) origin -- ha, ha.". Since the US form of government is largely based on French ideals at the time of its creation I think that would be a strange argument.
Quite why such a piffling detail as the choice of measurement system creates so much angst is beyond me. All measuring systems are arbitrary, with the possible exception of integers (counting). Even then the choice of base is up to the user.
Cheers
Greg Locock
Quite why such a piffling detail as the choice of measurement system creates so much angst is beyond me. All measuring systems are arbitrary, with the possible exception of integers (counting). Even then the choice of base is up to the user.
Cheers
Greg Locock
My kid (a junior in a U.S. high school) told me I needed to cut 2 cm off a board - I hit him with the board of course.
I just retired from a global company and used to get some interesting unit references. One guy in Canada asked if he could run 3 E3M3 of gas up a 2-3/8 string of tubing at 70C and 1,000 psig. Someone in Indonesia had a problem with 6 miles of 4064 mm pipe. etc. The "E3M3" reference seems to be unique to Canada, I asked "why not km-m2?" and got a blank stare.
Things are changing though. The post WAY earlier that said their Toyota had standard threads and their Ford and Chevy both had metric had a key bit of data in it - every auto mechanic in the US today has to have two complete sets of tools. That's expensive and I believe that over time the "standard" system will vanish from the auto industry because of pressure from mechanics and unions. They say in this country "as goes Detroit, so goes the nation" (or something like that) and not long after the autos stop mounting 16 inch wheels with 25 mm nuts, the metrification will accelerate. We're already fine with 5 liter engines.
There's nothing inherently good or evil about any system of units - they are simply a means to describe the physical world. The only evil in this discussion is the engineer who fails to specify units. If we are rigerous in always describing what we mean then the opportunity to screw up in a big way is less.
David Simpson, PE
MuleShoe Engineering
I just retired from a global company and used to get some interesting unit references. One guy in Canada asked if he could run 3 E3M3 of gas up a 2-3/8 string of tubing at 70C and 1,000 psig. Someone in Indonesia had a problem with 6 miles of 4064 mm pipe. etc. The "E3M3" reference seems to be unique to Canada, I asked "why not km-m2?" and got a blank stare.
Things are changing though. The post WAY earlier that said their Toyota had standard threads and their Ford and Chevy both had metric had a key bit of data in it - every auto mechanic in the US today has to have two complete sets of tools. That's expensive and I believe that over time the "standard" system will vanish from the auto industry because of pressure from mechanics and unions. They say in this country "as goes Detroit, so goes the nation" (or something like that) and not long after the autos stop mounting 16 inch wheels with 25 mm nuts, the metrification will accelerate. We're already fine with 5 liter engines.
There's nothing inherently good or evil about any system of units - they are simply a means to describe the physical world. The only evil in this discussion is the engineer who fails to specify units. If we are rigerous in always describing what we mean then the opportunity to screw up in a big way is less.
David Simpson, PE
MuleShoe Engineering
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