Homebrew PCBs

Hello everybody in this list. I've a cnc machine purchased some time
ago, but never used. Now it's time to use it and produce first pcbs.

Can you help me to find an appropiate router bit to produce boards
with 12 mil width of nets and 12 mil spacing between coper nets. For
example, some microcontrollers from microchip comes in an tqfp 64 pins
in an 10x10 mm space. I need to find a bit suitable for this job, but
I'm very new to cnc world. Can you recommend what type of bit should I
use? Diameter, angle, material, best rotation speed, ...?

Any help with this will be appreciated, as I've never used my cnc before.

First off would be making sure you have a very accurate machine and a good
setup, and also a spindle with very little runout.  You need to hold your
boards dead flat, and you'll need to have control over your cut depth to
within a thou.  Precision engraving where the negative space matters is
pretty brutal.

Precisebits (precisebits.com) sells the best quality micro endmills and
engraving tools I know of, and I've looked pretty long and hard as I go
through a few thousand dollars of them a year.  Harvey Tool also makes nice
stuff, and more specialized micro mills than anyone else I know of.

-Bob Garrish
 (I own and run a CNC machine shop, mainly doing small and high precision
parts)


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