Homebrew PCBs

Some days ago, I mentioned a disappointing experiment of mounting a
Staedtler Lumocolor 313 Red Superfine marker pen on my CNC drill and
programming it to draw the artwork on the copper surface.

The software and CNC worked fine. The problem is that the Lumocolor
Superfine pen, while having a supposed point width of 0.4mm, ended up
drawing lines that bled out to more like 1.0mm thick, possibly due to a
combination of the ink properties and the copper. This was way too thick
for boards using VLSI parts, especially if traces need to run between IC
pins.

Solution came to me this morning - so here's the very easy recipe for
all to try and enjoy. Takes less than half an hour.

1. Get 2 pens:
  - Staedtler Lumocolor 313 Red Superfine
  - Staedtler Pigment Liner 0.1mm Black

2. Using long-nose pliers, carefully pull the points out of both pens

3. Flush the 0.1mm Pigment Liner pen's point till it's almost completely
   white.

   You may need to take a mouthful of water, and blow it out through the
   point. Alternatively, you could dip one end in water and suck through
   the other end, making sure to spit out and rinse your mouth

   Either way, this step should only take a minute or two

4. Dry the freshly evacuated and rinsed 0.1mm pen point, trying to soak
   up as much of the water as possible from both sides

5. Carefully drill a 3.0mm hole in the bottom end of the Lumocolor pen.
   Retract the drill bit every 1mm, and remove the black plastic
   particles. Don't drill any deeper than 5mm total!

6. Take the 0.1mm pigment liner pen point and insert it
   carefully into the Lumocolor pen body.

7. Gently shake the lumocolor pen in a circular motion, in a way of
   trying to drive the red ink through the 0.1mm tip. Shake 3 or 4
   times, wait a few seconds, shake again

8. When red ink starts coming through the point, draw a lot of lines
   on a piece of paper, so you run out any remaining water traces and
   end up with pure Lumocolor red ink.

9. Your freshly-hacked Lumocolor pen is ready to use for drawing fine
   etch-resistant traces. Allowing for ink bleed, you'll end up with
   about 0.3-0.4mm thick lines, which should be adequately fine even
   for artwork using SMD components.

10. Mount the pen onto your CNC rig or plotter, and start making boards

Enjoy!

-- 
Cheers
David