OK, thanks. Anyway, there are AC servos which use less voltage than the mains, but in all cases they require a beefy transformer, a large driver and even the motors are larger. I have no space or need for that at this moment, even if it would be much better for the purpose. Remember that this is mostly just a test, a proof of a concept with a goal to build something to play and learn with.

I think the only difference between AC and DC servo is that an AC servo driver has the rectifier built into the driver, while a DC servo must be fed using an external DC PSU with a rectifier circuit in the PSU. When I say DC servo, I mean just that the driver needs DC current, but it is still a servo, and NOT a closed loop stepper. Basically, I have written off the use of closed loop stepper, mainly based on what Dean said before, except that I will not at this stage buy a large one, but aiming at a 180W type from JMC, namly this one:

https://www.aliexpress.com/item/3294...79092e0eprgamN

I checked the manual and the software, and must say I am impressed considering readability, configurability and contents, and since this will be my first servo, I think that is important. It fits my size needs and I don't have to build a new PSU / control box. If in the end it turns out to be too weak, I can always move the motor to my CNC and replace a NEMA23 stepper of one axis, and buy a new and stronger servo with break as Dean suggested, but that will not be now. First I want to finish the project and see it working.

I think you are wrong about gearing. Torque is multiplied by the gearing, so indeed I gain a lot. Of course, since the stepper is pretty weak, it will not be much at high RPM, but never the less, it will be six times (minus some losses, but we can ignore that here). Of course, gearing down is giving the most torque benefits in holding, but there is a benefit even when rotating. Of course, that would not be needed at all if I had a large enough motor, but that's for later times.