Homebrew PCBs

The center hole trick works with flexible regular drill bits.
With high speed carbide they really do not significantly flex.  If doing
high speed CNC drilling the center hole is unwanted since it can put slight
sideways load on the drill bit and it is much better to hit a clean copper
surface.
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From Fabio Sent: Thursday, December 23, 2010 03:57
This might sound a little naive, but I have big bit centering problems too.
I do etch the hole in the center of the pad, but when a carbide bit at 30K
RPM hits the board it eats away everything in its way, no matter whether
there a center hole or not. Or you mean stopping the bit after every hole
you drill? Would work, but sounds a little unpractical. Could anyone please
explain? 
Thanks,
Fabio

--- In Homebrew_PCBs@yahoogroups.com, "Andrew" <a_wake@...> wrote:
>
> To expand a bit -- I am only familiar with KiCad, but would guess the
others provide a similar option:
> 
> KiCad allows you to choose either an exact hole size or just a pin-point.
The latter helps to avoid over-etching the hole, but still leaves a little
point in the copper that will guide the drill bit.