Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Stefan,

Carbide can take a LOT of heat, but glowing red or white hot isn't
such a good idea. As mentioned, don't quench it if you don't have
to but it shouldn't hurt in reality. A green grinding wheel is very
soft by comparison to the white one you are using now. It will
abrade away very quickly - the nature of the beast when grinding
carbide. Don't inhale any of the carbide dust - it's nasty stuff.

The type of tool you ground is referred to commonly as a half round
drill. They work great in many materials including brass, copper,
plastics and even glass.

Recently I tried to grind one for isolation milling - what a joke
that was. I just don't have the eyes for it anymore. I tried all
my optical aids and nothing would bring the grind into focus to see
what I was doing.

The burr you are getting is probably caused by not having clearance
on the backside of the cutting edge. It is very hard to visualize
where it (the clearance) needs to be but if you look at a normal
drill, you will see how the backside of the cutting edge rises up.
The half round drill needs this as well, but it is very minimal when
done correctly.

With all that being said, you must have done pretty darn good if you
ground the drill with a white wheel and got it to cut a hole in the
end!!!

Chris