Thanks, Dean - I was expecting to do that. As long as the default tuning parameters are near enough, I expect that I can muddle through that process. I do have a reasonable idea what P and I parameters do in a control system so as long as we don't make big changes and keep testing, we'll get there. This project is a bit simpler than yours anyway as we don't have tool changers or spindle servo drives to cope with.

I expect that fitting and wiring home switches shouldn't be a major exercise, but the existing machine has single limit switches on each axis with operating ramps (it uses roller-operated microswitches) at each end. I need to check if the controller is going to be happy with connecting the string of limit switches to both + and - inputs - might confuse it to get simultaneous max and min limit inputs. I'm going to be reading manuals for the next few weeks, I guess.

Muzzer - thanks also for your comments which have given useful background info. If I were doing this for myself I might well have looked into reusing the existing motors with those CNCdrive drivers, at least after checking that the motors did have encoders fitted. Given that there is already a suitable DC power supply in there, this might not have been a major exercise. However, the machine is in someone else's workshop 10 miles away so keeping it simple is key here.

We might end up with a pile of bits for eBay to sell as spares, so there is a chance to recoup some of the money spent.