Quote Originally Posted by alboy View Post
Oh that applies to so many things in life lol. How are you, long time no speak. The CS labs controller has been working great by the way.

It just got me thinking that on a large machine, which is better ballscrew with rotating ball nut or R&P. In my mind (not always the best place to be :-) ) I would think that R&P would be cheaper to implement with better stability and speed (accuracy?) on larger machines. Now I am up for being proven wrong in my assumptions, best way to learn something :-)
Well it's no brainer really the Ballnut wins every time if talking which is best. R&P doesn't come close in terms of accuracy or efficiency.
However rotating nut is more involved than rotating just the screw.

That said R&P comes with its own problems so can be just as involved. For instance, a ratio is required to get required resolution, which brings its own complexities. Then some mechanism is prefered to help reduce backlash by keeping constant engagement of the pinion with the rack which again brings some complexitys.
Also, careful positioning of the rack is required to avoid chips and dust from interfering with motion. Care is needed to keep rack clean so much more maintenance for the user than is with ballscrews.

Then you have to factor in the lower efficiency of R&P so larger more expensive motors/drives are required. All this soon gets expensive fast.

In performance terms then R&P can allow higher feeds for less cost but this does come with a cost of resolution. But the same can be said for ballscrews because very difficult or should say expensive to have high feeds and high resolution.

Take your pick but ballscrews will win every time in which is best battle.