Servo as a spindle motor replacement - what to look out for?

[m_c]

You've got the right tree.

There will be two main gearing ratios. One is for the input pulses, and one will be for the emulated encoder output.
You want to change the input pulses.

I've not got time to check the manual to see what they've translated the terms to, but try changing one setting at a time, reboot the servo drive, and try it.

[JAZZCNC]

Ok well, your problem is a little worse than you think because 100Khz won't give you 2000Rpm at the Servo. The encoder on the servo is 2500ppr x 4 (quadrature) so 10,000ppr
So 100Khz will only give 600Rpm (100,000/10,000*60).

So to get Full RPM out of the servo you need to use electronic gearing so watch this video I did because I'm not explaining it all again.!!

You could possibly use the E-gearing to give you what you want and then feed the Servo Encoder output back into UCCNC, thou I've got a feeling UCCNC will only allow a max 1000ppr Encoder to be used.?