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.