Homebrew PCBs

I have built my own. I am using Dremel and I could
able to use 0.0135" (~0.34mm) bits without any
breaking. I have also tried to use 0.0083" (~0.21mm)
bits but no way with Dremel, I think 0.0135" is the
limit.
Cheers,
Volkan

> ... is the Dremel run-out good enough for 20 mil
(0.5
> mm) bits?