"Phred" <[email hidden]> wrote in message
news:[email hidden]...
Quoted message said:In article <[email hidden]>, "pablo"
Quoted message said:Quoted message said:
"Sheldon" <[email hidden]> wrote in message
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Quoted message said:What is really interesting is that most cars on the road today are
manufactured in Japan, Korea, Germany, Canada, Italy, England, etc.
where metric is the default... bet you didn't know that.
No, most vehicles in North America are still manufactured domestically by
the traditional Big 3 (About 60 %) --although the portion of vehicles
produced in Mexico has been steadily climbing.. The other OEMs are
making
Quoted message said:Quoted message said:more of their products here if they intend to sell them here. And,
believe
Quoted message said:Quoted message said:it or not, we're finally designing in metric units.
Been engineering internationally for 35 years, managed technical in several
countries, went thru the hard-soft conversions of ANSI and ASME, have been
on ANSI committees and developed international standards for over 30 years,
and have used standards for metals and fasteners in detail - four
observations -
1) it was contra-logical for the leader of the free world to take the
world's largest economy and the world's leading body of standards and change
THAT economy and technical population to metric.
And in particualr, reducing the quality of standards is not the way to
stay better (and there is no question that many of the fastening standards
and metal standards were lowered, and, I might add, one reason why the
british standard has not gone away)
Logic says one should to let that which was working better than anywhere
else continue to work, and let that which isn't working as well evolve into
a standard around it.
2) metric was and is a greater standardizing mess than english units.
Before the metrication push, the english countries used inches for
machines and feet for lengths of large items like pipe. The others used
meters, cm, mm, and dm. It was far easier to remember that there were 12
inches in a foot than it was to remember that the french plants were using
mm, the italian plants were using dm, the scandinavian plants were using cm,
and the english conversions were in m.
3) Dividing by ten is not as easy for humans as dividing by 3 or 4 (the
"basis" of 12). The 3 and 4 are intutive, ten is computational. Yes, on
paper, dividing by ten is easier. In your head, 3 and 4 is easier. In
computers, 4 is far far easier than ten. Computation was a red herring
4) The basis for material choice goes to tests, and the tests are derived
and created in a number system according to that society's needs. If all
you needed was strength because another std covered impact, corrosion,
drawing, etc. then that was all that local std included.
Thus, metric based standards were applied to ordinary materials common to
simple design in metric countries - but if the standards are not complete or
use different basis for design (as was and still is the case in many metric
standards such as DIN), the design using those stds suffers from lack of
what we called transferrence, from lack of specificity, and it becomes
costly because the usual tests for material and the material must be
compounded and prepared to that "special in metric standards not special in
english standards" criterion.
One would think that the old british stds would just be converted to
metric numbers, but it doesn't work that way for several reasons - the
biggest is that metric stds (DIN) are effectively controlled by govt bodys
and nationalistic interests. E.g., if the Germans don't need a charpy
impact test on their steel, and the US products are designed to account for
it, then there is a German economic advantage to arrangin g the stds so that
US producers have to add that convert and add that test to their steel
specs -or lower their prodcut quality. Repeat that scenario a dozen times
for each material, and a hundred times for fasteners.
This week, I needed an 8mm x 1.25 x 120mm 8.8 bolt for shear loading.
Not only was it $3.00 plus $25 for special order for that length, it lacked
the specs I needed to decide on its appropriateness for the application. I
used a 5/16-24 x 4 1/2 inch gr 5 for $0.40, fully spec'd
I think few outside of the technical world understood how far the US and
GrBritain was ahead of the rest of the world techncially when the
metrification push was made. To get euro steel was like going to the
metric-stds market and being able to buy only beef or potatoes, and then
going to the US market and being able to buy all meats and all vegetables.
Metric Europe was in the bronze age at the time. I had a hunch that the
move wasn't made to make the US better, it was made to slow down the growth
and reduce the increasing gap between the US/Britain/Australia and the rest
of the world.
oh, well... you get what you ask for, and if you can't ask the right
question, I guess you don't get what you want.
nuff catharsis
3)
(For a long time, we
Quoted message said:Quoted message said:released our part prints with metric units but the basic dimensions were
still developed in the English system and then simply converted.)
Yeah. 2" = 50 mm and then they wonder why nothing fits properly. ;-)
Cheers, Phred.
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