Thank you Jim, I'm just trying to learn how this all works as I have had so many other things I was fixing, replacing and repairing on the Mill that I never gave my spindle motor any thought before this year. Now that I have a lot of other things in hand I would like to consider this as a potential project. So from what you wrote we can't look at peak torque really, we have to just look at continuous torque numbers and in that case I understand what you're saying. How do big machines like HAAS VF series (and many of the newer machines out there today) run their spindle? Are they using something different than servo motors? I'm just trying to learn.
The other thing I'm trying to do is possibly get rid of the need for my rotary 3-phase converter. Right now I use it because this mill has a 3-ph 2HP motor driving the spindle but if I replaced that motor I could easily re-wire the machine to run off of my 220v single phase at home. That would be pretty cool. I just don't want to cripple the machine in the process. So that's why I want to make sure I do good research here first if you guys are willing to help me out with my knowledge gap.