Grant wrote in message
...
On Tue, 19 Apr 2011 08:25:39 +0100, "N_Cook" wrote:

Baron wrote in message
...
N_Cook Inscribed thus:

1.8mm slabs of porcelain under TO220 devices.

I would check that ! Its more likely that they are Beryllium_oxide !
http://en.wikipedia.org/wiki/Beryllium_oxide

Tried grinding a clearance notch on the side of one
pad but got nowhere as ceramic.
Not only that but I had no trouble holding the slab in fingers while
trying to grind a slot, it was barely getting warm - good thermal
insulator or small grinding wheel not generating heat as not cutting
into the material ?

The dust from grinding or abrading Beryllium_oxide is highly toxic !

--
Best Regards:
Baron.


Unfortunately it would not grind. I assume it was not heating up because
the
grinding disc was just running over the surface without even rubbing ,
let
alone grinding, so no dust, still the flat edge . Does BeO have that sort
of
translucent appearance of porcelain? I've managed to grind small sections
of
the ceramic used is high temperature "chock block" connectors, that has
a
normal solid white appearance. But given its use here then presumably
BeO.
It was the slightly milky/translucent porcelain-like appearance that
convinced me.

Only BeO I've seen was pink, and I'd not try to grind it, toxic!

Safe if not shattered.

Grant.


I've seen pink TO3, presumably BeO, insulators before but they did not have
this transclucent like appearance.