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Re: Rant - inexcusably stupid redesigns



On Thu, Aug 16, 2001 at 02:49:46PM -0700, Curt Voss wrote:

> I always wonder, what the f**k are the engineers thinking when they
> pull this kind of crap? Are they totally oblivious to the effect their
> changes have? 

In general, changes like this are the fault of the purchasing dept, not
engineering.  Usually it is done because the replacement part will make
the shipped product cost 19c less to produce.  

I used to work for a company which produced cryogenic liqid tanks.  There
In this industry, you need to be careful of thermal stresses where
different materiels interface.  In one location, I needed a brass
T-fitting to thread onto a stainless steel pipe thread. I specified on the
drawing and in the parts list a forged brass fitting.  The part that the
purchasing folks got was made of extruded brass.  Within 3 months, we had
a 70% return rate because the fitting was cracking.  When I discovered
that a substitute part had been used, we found that the purchasing people
had changed to it because it was 15% cheaper and it looked the same to
them.  I ammended the part description to include a manufacturer and part
number and added "NO SUBSTITUTIONS."

Dan



-- 
Chief test pilot, M&M E&A Sub-Supersonic Invisible and Noiseless 
Defensive Second-Strike Offensive Attack Bomber.

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