T
Terry Given
- Jan 1, 1970
- 0
Joerg said:
I would also point out that "sharp" (IOW not well radiused) edges can
cause long-term problems with winding insulation, which is stressed
around a tight corner. The inside edge insulation gets squished up, and
the outer edge gets thinned out. Add heat + time, and creep may well result.
I had a hilarious argument with a so-called mechanical engineer about
this once. He reckoned that a 2.8mm dia. O-ring, bent 90 degrees around
a 1mm radius, maintains its shape. I reckoned he was an idiot. I was
right, water poured in at the edges. Of course he did have a 2.8mm
channel for the O-ring at the corner (cf 2.5mm elsewhere). The O-ring
thinned out by about 0.3mm. Even showing him the o-ring under a
microscope wasnt enough to convince him. It convinced me never to use
him again.
His fix was to use a 3mm O-ring, which made the unit impossible to
assemble. His fix for that was to use vaseline, which then destroyed
(completely! looked like a sledge hammer had been used) $300,000 worth
of polycarbonate-based plastic enclosures, which *he* had designed and
made. His choice of material, too. It took about 3 months for the scale
of the problem to become apparent, in the field. At that stage, lawyers
were called (and I learned a lot about the interaction of plastics and
other goodies)
Cheers
Terry
