One of the nice things about having a CNC router or mill is the ability to quickly make printed circuit boards. We use Cadsoft Eagle schematic layout editor and PCB autorouter to make one of a kind boards. The freeware version can create boards as large as 4″x3″. The price for the Standard version is very reasonable considering how much other schematic entry EDA programs cost these days. For a quick Eagle tutorial, Sparkfun has written a short lesson on how to get started on using the program.

Once the schematic is created and the printed circuit board is routed, the next step is to generate the gcode isolation and drill programs so the CNC can mill the board out. I used gcode-pcb which is a ULP Eagle script that easily creates the tool path isolation gcode programs. There is a Yahoo Newsgroup and this site for more information on how to install and use the ULP script.

For this video demonstration, I made a circuit board for the Joule Thief from www.evilmadscientist.com. This is a simple circuit that will drive a 3.2volt blue LED with a single 1.5volt battery.

The milling and drilling gcode files that will run under MACH3. This is a slightly different board layout than the one featured in the video with larger pads for the inductor.

This is a view of the PCB from the top.

The gcode backplot. This is the path the cutter takes when milling the board.

Short video of the CNC milling out the circuit board.

1/8″ V-bit cutter (available at http://www.thinktink.com/)
Rapid speed 125 inch/minute
Cut speed 30 inch/minute
MACH3 cnc controller
Minertia T01L-44 servo motors with 200 line encoders
UHU Servo drivers
Proxxon IB/E high speed spindle at 20K rpm

The completed Joule Thief, the original version featured in the video. The inductor is glued to the bottom of the board.

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