Since Alessio has been etching his own PCBs, he’s hit upon the most tedious part of the process, and the reason homebrew SMD boards are so awesome: drilling your own boards is a pain. While Alessio’s CNC mill takes care of most of the work, aligning the pre-drilled boards and correcting for any scaling issues from the mask is a bit difficult. With the help of a transform matrix, though, drilling PCBs has never been easier.
While the Gcode running the mill may be accurate, the actual manufactured PCBs might not be. If the extents on Alessio’s board aren’t exactly aligned with the axes of the CNC mill, the drill holes end up where they’re supposed to be. To solve this problem, Alessiowrote a PCB drilling transformational matrix calculator. The basic idea is by drilling just a few holes, Alessio is able to calculate any offset required in the Gcode with the help of a little bit of linear algebra.