​First thing was to measure the outline of the existing PCB's and measure the offsets and sizes of the mounting holes, then get the rough positions of the various connectors for the motors, the connectors are standard fair so easy to get and there is some play in the position. I moved the USB from side mounted to front mounted instead, i could have stuck with the back like the parallel port but it was just easier.  

Mounting it to come out the left side was just annoying for desktop placement.

Then i tested the motors with a couple of the BigEasy's i had lying around, they're basically  just the Allegro stepper drivers with a trim pot and current setting. 

I wired them to a ATMEGA 2560 and added a few limit switches ( forgetting pullups the first time, which is a bad idea since most on chip pullups aren't good enough even for limit switches. ) plus an "E Stop" circuit to  either brake or loose the motors.

We also sourced a new router from a guy who does them almost off grid in a caravan down by the, no wrong guy, but he does a great job . Initially when we started this project it was meant to be a basic cheap PCB MILL that could handle the accuracy required to do a SMD fine pitch board, like our $15,000 AccurateCNC does, but for < $1,000.

GRBL is a decent firmware its well tested, just added a home and limits etc. Then send down some GCODE and off it goes!