I am describing here the way I currently drill the PCBs I print with haxmark460. There was a lot of trial and error involved in the building process, but It's pretty quick to setup now that all the nuisances have been worked through. The demo videos show it in action.See https://hackaday.io/project/171775-haxmark460-home-pcb-printer for instructions on Direct PCB Printing with a modified laserjet printer.
Extract the RS540 12V DC Motor from the portable air compressor and print its case using Ender 3 or another 3D Printer. The file is
Attach the Dremel Chuck to the end of the motor axis. It's also possible to don't use a chuck by printing the drill bit threaded holder (file provided). If you don't use a chuck, put a small piece of soft rubber on the outside of the PCB drill bit to keep it from "dancing" inside the holder metal tube.
Glue a 3.5" HDD magnet to the outer wall of the 3D Printed Motor Case
Remove the Ender 3 Extruder head and attach a 90° steel angle large enough to hold the drill attachment. I don't have pitctures, sorry, but it's shown in the demo videos. Don't forget to screw the extruder head again.
The Drill Attachment Wiring
We are going to use the Ender 3 Extruder Cooling Fan to control the drilling motor. Cut the wire close to the extruder head. I use a simple switch (a DPDT one will do) to enable or disable the motor control. A resistive voltage divider is used to lower the Ender 3 Fan voltage from 24V to 10V.
Glue the IRF3205 (with the gate-source resistor) to the motor case (it won't usually heat enough to justify a heatsink). A detailed schematic is shown below:
3. To power the drill, use a regular computer 12V PSU. My drill attachment has 2 plugs: one for power (goes to the PSU) and another for switching (goes to the ender 3 fan)
Drilling Part I
Place the PCB to be drilled on top of a cardboard sheet (it doesn't need to be thick, mine is 1mm), which goes on top of the Ender 3 printing table. Hold everything with clamps on the corners. Alternatively, you might use double-sided stick tape.
Manually position the drill (and the drill head) over the point you wish to set as the (0,0) (X,Y) point. The drill should just barely touch the board and shouldn't scracth the copper when it is moved.