Stepper vs. Servo Question for Turning Center

BigJohnT wrote:

That's bigger than I imaged for nema 23, but what the heck do I know. The control panel is almost as big as the lathe! JT

I know... That's just ANOTHER of the upsides of getting rid of that thing...
The steppers are Berger Lahr RDM 596/50 5 phase steppers. Approximately 110 oz/in.

EDIT - I should point out that EVERYTHING is contained in that cabinet. There is an elaborate frequency drive for the spindle motor that consists of 5 or 6 different cards/boards, plus stepper drives, plus controller cards/boards, etc... it's a mess. It's very Austrian...

Yes, that is its predecessor. The Compact6 lead to the 120 and then 220, some ( like my own ) with a P for pneumatic control of things like chuck, tail, parts catcher... Same basic frame, different spindle and accessory options. Many had bar feeders. My own did at some point. They are seriously over built machines, inside.

So what kind of motor were you guys thinking of in regard to spindle positioning? ( C axis )

andypugh wrote:

I am not sure how well positioning works with an induction motor + VFD. I believe it is OK for toolchanger alignment, but I don't know if it would be stiff enough for C -axis work.
You definitely need a flux-vector drive, my own experiments with a traditional v/f VFD were less than a huge success.
For proper rotary-axis use you probably need a servo, and a big one too. Though I am planning to experiment with a washing machine motor.

Thanks, Andy. If I'm asking too much of it right now, it is likely best not to go so heavily into the modifying side right out of the gate, and just get the thing running, for now. I can always experiment later. I will have to view that video later. Thank you.

Another question here regarding the whole servo conversion and Mesa cards.

That tool changer that uses the 24VDC motor... does that have any effect on the choice of 5i25/7i77 combo? Will controlling it be done from those, or will I require other hardware? Hopefully someone will know off hand, and Peter will chime in as well.

Thanks, John. I have to admit that I am kind of worried... It just feels like I am "missing" or overlooking something big, here....

PC
Servo motors
Servo drives
Servo encoders
Spindle motor
Spindle motor VFD
Mesa 5i25 and 7i77
Power supply transformers and such
Various control panel bits ( MPG, buttons, monitor )
Wire it all together.

I know I will eat these words later, but it just seems too easy at the moment. Hence my thinking that I am missing something important.