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.
