Stepper motors and linear scale closed loop setup?

This is a very good input, thanks for that. Any alternative solutions that could help avoid a indirect drive? Maybe use >>64 micro steps + higher torq Stepper Motor ?
(I try to keep the bill of materials small if possible)
Warm regards and again, a humble thank you for these replies.
R.

I'd not install Glasscales if money is a concern

Rightly or wrongly, I plan to convert my Colchester Bantam to CNC using step/dir servos, ground ballscrews etc. I blame lockdown.

I will take every sensible measure to minimise backlash but plan to integrate linear scales on X and Z, as it would seem rude not to.

I have a 5i25 / 7i76 combo but believe I would be short on encoder inputs. I'd need 3, including a spindle encoder. Possibly 5 if I were to feed back from the servo drive encoders too, although I don't imagine that would be particularly worthwhile. What's best for me here - can I add a second board alongside the 7i76 or is there a better solution that is cost effective?

Have a look at Mesa 7i85 or 7i85S, should have 4 encoder inputs and should be usable with 7i76.
Not sure as i never used a 7i85 or 7i76, for some strange reason, should have since i had over 40 of Mesa boards ! :blush:

Looks as if the 7i85 connects to the 7i76 using RS-422 via one of the on board headers? I hope so, as I'm expecting to receive one tomorrow. I notice that the 7i76e has a couple of ribbon cable headers for expansion whereas the original 7i76 (like mine) doesn't, while the 7i76 manual shows the 7i76e. Bit confusing.

Tangential question - what are the preferred GUIs for lathe use? I see Gmoccapy has a lathe mode but TBH it doesn't seem as slick as the mill version which I'm guessing was the original target.

The 7I85 connects to a FPGA card not the 7I76