Evening David,

How long does it take to do a board that sort of size (roughly - obviously
it depends on track complexity) ?  Is it comparable in speed to chemical
etching ?

I noticed you've milled just the gaps between tracks; have you tried to
take larger areas of copper off the board at any point - just etching the
gaps between tracks seems to be common on the CNC boards I've seen on the web,
but I personally don't like to leave floating copper.  I'm just wondering if
it's too much hassle to do this (ie. takes too long) ?

How long do you reckon the tools will last before needing to be
replaced/sharpened ?

Cheers,

Pete Restall

--- Original Message ---
I built a CNC machine from a milling machine using EMC2 software and an
interface of my own design.  While I did this orginially to do aluminum
with, I recently have been doing PCBs with it.  For one board that uses a
2mm x 2mm chip with 3 pins on opposite sides I use a 20 degree engraving bit
for a gap of about .018".  For less critical work I use a .029" end mill set
only deep enough to remove the copper and not the board.  You can see a
board I am currently selling at
http://www.dv-fansler.com/dvf%20Technologies/lx200_keypad_sim.htm along with
3 pictures.  This board was done with the .029" end mill.  I have done over
20 boards on the same end mill and they still look like the first one.

BTW - I do my layout in AutoCAD and then convert it to ngc with a free lisp
program called Realize.

David

David V. Fansler
s/v Annabelle
dfansler@dv-fansler.com
www.dv-fansler.com
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