On Wed, 09 Nov 2005 09:46:11 +0100, Mike Young <
mikewhy@...>
wrote:
> Can I conclude, from the lack of choices for 1/8" shank center drills or
> countersinks, that center drilling the itty-bitty PCB holes isn't popular
> practice? Too dumb a question to bother answering?
nobody seems to do it, no.
With the carbide bits running at high RPM they will usually easily center
the hole without any wandering. It isn't even preferrable to have a
pre-drilled hole, as enlarging it puts much more stress on the drill
(without limited feedrate that is), it tries to take out much larger
pieces because it isn't held up by the center stuff. I've broken some when
enlarging holes.
Sometimes when i need really large holes, like for mounting, i drill the
center with like 1mm and then enlarge them on the big drill press.
Countersinking isn't really desireable either, but i have seen sinks with
the right shank on ebay, made of carbide. A sharp carbide drill doesn't
leave much burr and they surely weren't used to countersink component
holes.
ST