Re: Lead Screw vs Ball Screw

Hello,
In general, a ball screw has very high efficiency. In other
words, there is little resistance. In a Z axiz situation, a ball
screw will tend to let the head fall, so a brake is recommended.
Leadscrews with their high resistance, are mostly self braking.

As for single ball nuts and preloaded nuts. It's all in the
backlash. A single nut will have around .002" - .006" backlash. A
preloaded nut is adjustable so that you can virtually eliminate all
backlash (much more expensive but worth it in my opinion).

You can simulate preload on a standard leadscrew and nut by using
2 nuts coupled together with some sort of spring and/or adjustable
screws, but your resistance gets even worse.

In 5/8 ball screws a 5 thread per inch pitch (or .200 in./rev) is
quite common, so should be no problem. Most ballscrews I've seen are
right handed thread (standard), some are available with left hand
thread which come in handy for machines like lathes/mills with are
handwheel operated.

Good luck.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "ralaco" <ralaco@y...> wrote:
> I want to replace the lead screw from a 5' X 8' Router's Z-axis,
with
> a Ball Screw and I have some questions:
>
> What's the difference between Standard ball Screw and Preloaded
Ball
> Screw?
>
> Do a 5/8" Ball Screw have the same performance as a 5/8" lead screw?
>
> How to ask for a Ball Screw to get the same as 5 treads per inch in
a
> lead screw?
>
> Raul