"Carl McIver" wrote in message
...
"Wayne Lundberg" wrote in message
...
I've seen a few RFQs from Boeing subs showing CAD drawings using the
traditional right-side-up cone indicating the orthographic projection to
be
for standard Imperial ft/inch/lb.

Has anybody seen any RFQs from Boeing calling for metric dimensioning?

Ironically, different divisions of Boeing have different drawing
standards for different reasons, and the standards evolve constantly, as
one would expect, given the different tools available for design.
Facilities uses Autocad, Commercial Aircraft uses CATIA (forgot the name
of the system the 787 uses, which is a bit different) and my tiny little
lab uses Solidworks. You'll find just about every system and standard
that exists all in use at this enormous company that isn't micromanaged so
tightly that someone cares about such things.
Aerospace equipment and standards, having been developed using the
traditional units, are still being made that way, and since they're
expensive due to regulatory issues. Imagine what the price of a rivet
would be now that it has to be redesigned using metric standards and then
find someone who wants to buy them... just so they can pay more? Airbus,
Embraer, and Bombardier all use inch fasteners. Would you as a passenger
think you need to pay more for the plane just because the drawings are
done using one standard over the other.
On the other hand, NASA has made the announcement that all future space
missions will be metric. Don't know how much of that design dictates
metric fasteners, but it'll be interesting. They'd like to avoid the unit
conversion that has resulted in a few embarrassing accidents. My lab will
ask for quotes in both metric and inch, sometimes a mix of both, depending
on the project, the materials, the customer, and the designer. I'm
getting used to working with mixed units, although I'm not to the point I
prefer one over the other.

That's an interesting story, Carl. I think a lot of pro-metrification folks
fail to separate the advantages metrics offer in scientific and some
engineering calculations from their complete *lack* of advantage in
measurement -- which is what we're talking about, in manufacturing. As soon
as someone starts talking about the conversion of odd, old units in the
traditional "Imperial" system, you realize they aren't talking about the
issue as it really exists. Where it matters, metrics are used in the US.
When it comes to measurement, the advantages of metrics are illusory.

--
Ed Huntress