more ball screw/CNC retrofit questions

I'm a bit new to this, and I'm still trying to figure out exactly what I ultimately want to do so please bare with me.

Are there different types of ball screws? What should I be looking for if I want to try to find ball screws to retrofit my lathe or Bridgeport to CNC? I see Bridgeport retrofit kits that have the X and Y axis ball nuts as one unit and are likewise fairly expensive. Is this necessary or would it be relatively easy to use two independent (less expensive) units? Such as the ones that seem to be common on ebay?



Lastly. Can high rez. DRO quills be used to supply the feedback that is lacked in a stepper motor type system? Is there such thing as a comparator either in the controller or PC software for this? Likewise, am I just better off with servos to achieve higher accuracy/repeatability?

Thanks

Peter-



---------------------------------
Do You Yahoo!?
Yahoo! Health - your guide to health and wellness

[Non-text portions of this message have been removed]