Re: newbie question

> Yes, ball nut is the proper term. Yes, there are inner 'works'.
> The works are ball bearings. So, the nut does not slide on the screw,
> the rolling balls make it a rolling action, thereby reducing friction (and
> wear) to minute levels. There is a rounded track in the nut, and the
> balls roll to one end of the track, so a recirculating tube of some
> sort is provided to return the balls back to the other end of the
> track. If you put two separate circuits of balls in one nut, and either
> make the two tracks slightly off the screw pitch, or put springs
> between the two nut sections, you can preload the two nuts against
> each other. This makes an anti-backlash screw. Depending on
> design, you can get screws that will deliver thousands of pounds
> of linear force, with backlash on the order of .0001" or so.
> Obviously, for a precision machine, or a CNC where smooth,
> complex motions are required, removing backlash is a very
> desirable thing. The reduction in wear and friction is an added
> benefit.
>
> Jon

I was surprised to learn that the antibacklash type ballscrews with 2
ballnuts back to back have a much reduced efficiency. Standard ball screws
are in the 90% range and I think the anti backlash type are in the 60% range
which does away with some of the ballscrew's advantage.