Hi,
I actually made a spindle a few years back using a second hand Allen Bradley servo 1.8kW, 6.1Nm (cont), 18Nm (overload), 3500rpm.
I mated it to an ER25 tool holder running in P4 angular contact bearings.

I've used it a lot for steel and stainless where you need slow(ish) speeds but high torque.

I was very careless and had this in the bottom of my mill enclosure when it was not in use and coolant got into the encoder and wrecked it. I have yet to save up the money to
repair or replace it. Very stupid and very careless of me.

Craig