I realized another bug when milling my first actual project on the mill:

pcb-gcode, even though many people seem to be using it and the documentation seems excellent, seems to have quite a lot of bugs that are easy to fix due to Eagles C-like scripting language.

The latest bug I found and hopefully just fixed is the issue that spotting holes during the etch step drills all the way to DRILL_DEPTH right after the first hole was spotted properly. Spot drilling is supposed to help a manual drill step by creating a center hole for the drill press to work with.

However, after the first proper spot drilling, the V-shaped engraver bit got punched into the PCB all the way to the drill depth (1.65 mm) which widened my holes quite a bit, shrinks the restring unnecessarily, it costs time, it wears out the engraving bit and it's generally... simply a bug! I don't yet understand why the first hole and all other holes are handled separately but I guess I will find out as soon as I work on my next project.

To make things a lot easier, I also created a github repository for pcb-gcode. I have no idea why the original author is not using github to distribute the software...