Great info, thanks. By "performance" are you referring to speed or accuracy? Speed isn't the end of the world for me as it's a hobbyist machine at the end of the day, accuracy would be more of a concern though.

Cost being kept to a minimum would be preferable of course, so of your options:

1) VR milling 2.

2) Retrofit: Basic 12V BoB, remove control board, patch into stepper drivers.

3) Retrofit: Replace controller & stepper drivers.

4) Retrofit: Replace whole box with 5V or 24V system.

Option 2 is sounding the most appealing.

I've seen people referring to break out boards (BoB) all over the place but I've yet to find a simple beginners guide on them. I assume there is a standard format these BoB's come in and it's just a case of choosing a brand? All they do is take the signals from USB and separate them out into the relevant control signals? Forgive my very basic questions, have to start somewhere!

Thanks