Re: What makes a machine CNC ready?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Tony Jeffree <tony@...>
wrote:

>
> At 18:38 27/06/2006, you wrote:
> >This is an article of mine that appeared in the Digital Machinist,
> >special edition of Home Shop Machinist.
>
> Fred -
>
> Nice article, but I think you exaggerate the efficiency of the

typical Acme

> screw by a factor of around 2. The figures I have seen quoted are

in the

> 20-40% range, not 60-70% as you state.

Efficiency depends on the material of the nut and the surface
treatment of the screw and it also varies with the screw lead.

http://www.kerkmotion.com/pdf/kerk-catalog-2005.pdf

See page 18, 1/2-.2 lead through 1/2-.4 lead acme threads are .63%-
76% efficient.

What is highly exaggerated by the uninformed, is the utility of
rolled ballscrews compared to precision acme screws. "What does
that crunching sound mean?"

Fred Smith - IMService
http://www.cadcamcadcam.com/hobby