On 2013-01-15, David B wrote:
"Mike Marlow" wrote in message
...

[ ... ]

The picture on the web site says it is small - I don't remember the actual
measurement it stated, but it was small.

Could it be something to hold a PCB away from other components?
The PCB has a 10mm hole and one rubber ring goes either side and holds the
cast bit in place.
The point of the cast bit holds the PCB away from a frame and something else
fits in the silicon bit.

First off -- *Please* -- there is no "silicon" bit. There is a
"silicone" bit.

"Silicon" is an element, and is rather hard and brittle. It is
used (in precisely impure form) to make transistors and integrated
circuits, and is sometimes used for making lenses for infrared imagers.
(It is opaque to visible light.) The oxide of it is plain old sand.
And if silicon were used in breast implants, they would be *very* stiff.
The silicone used is silicone oil in a sealed bag.

"Silicone" is any of a number of compounds which would be
organic except that the carbon is replaced by silicon. This includes
oils and rubbers among other things. (And yes, I can testify from
experience that sand is an oxide of silicon. I experienced a situation
where the vapor from an overheated silicone oil caught fire, and after
it was put out, there was a lot of very fine sand scattered over the
workbench where it happened. (And no -- it was not from the fire
extingisher, since it was a CO2 extinguisher. :-)

This would appear to be a silicone rubber.

And as for a spacer and mount for a circuit board -- I would not
use aluminum for that -- even anodized. Yes, anodization is an
insulator, but it is usually not thick enough to be trusted. I have
experienced a breakdown of that insulation, causing significant damage
to my first kit computer -- an Altair 680b, FWIW, which I did manage to
fix.



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"DoN. Nichols" wrote:

"Silicon" is an element, and is rather hard and brittle. It is
used (in precisely impure form) to make transistors and integrated
circuits, and is sometimes used for making lenses for infrared imagers.
(It is opaque to visible light.) The oxide of it is plain old sand.
And if silicon were used in breast implants, they would be *very* stiff.


And make for some VERY abrasive women. ;-)