Denford Novamill 1996 Conversion, Hints & Tips Appreciated

[m_c]

You could run the mill using VR Milling 2, as I don't think VR Milling 5 supports serial. I use 5, however my machine had been upgraded to the USB controller, and came with a license.

You would have to get a license for VR Milling 2 to use it. Denford will sell you a new license, however if you were to find a somebody who already has a license, Denford are OK with you using licenses that came with the machine, but won't re-issue a license to anybody other than the original buyer.

Personally, with the absence of a working license, I'd be looking at doing some form of retrofit.
Basic level would be to add a basic breakout board, remove the controller board (that's the top board of the two boards at the top left of the cabinet), and patch into the existing stepper drivers (they're built into the lower of the top two boards), and then patch the other signals into the BOB, however you would need a BOB that supported 12V signals.

A more involved retrofit would be to replace the controller and stepper drivers. This could potentially give you better performance, as modern stepper drivers are far better than what is currently fitted.

Final option would be redo the control box completely. The 12V control switching, although far more robust than the typical hobbyist 5V, can be a problem. Most more industrial controllers are geared to 24V controls, so you'd most likely need to convert either up to 24V or down to 5V.
Although a Dynomotion KFlop and KStep combo would allow you to stick to 12V and give you pretty good stepper drivers, as the KStep is capable of 12-24V inputs.
I say pretty good, because although they're not as good as modern digital drivers, they'll still be an improvement over the fitted drivers, and if you were really wanting maximum performance, you'd need to look at replacing the motors with more modern ones.