Re: ball screw preferences

Mark,

Your experience is pretty typical of good quality, ground ball
screws and nuts. I suspect that kid (Balendo or Ken or Brand or
whatever his name is) is used to working with cheap, rolled ball
screws that are for utility purposes and not designed for precise
motion control.

For example, the cheap ball screws that are sold by some companies
(the 5/8" diameter units) are very crude, rolled screws and they
come out of the box with .003" backlash. Of the precision grade
screws that are ground, I have not seen any that had more than .001"
of backlash, new or used (with care).

Chris







--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mark Vaughan" <mark@...>
wrote:

>
> Hi Balendo
>
>
>
> My APTC hand mill is 5 or 6 though backlash on Acme screws.
>
> My recently acquired CNC mill is an Avon Circa 1989, built for an

aerospace

> group, with low hours on it. The ball screws that were several

thousand

> pounds each, the servo motors are 6KW, and fetch over £1000 second

hand, the

> servo cards are over £1200 each, it's a big professional machine,

and was

> very expensive in it's day and weighs several tons.
>
> I bought it cheap with a faulty CNC controller and moved it over

to mach3,

> and a G100.