Re: Rack & Pinion

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "george_barr"
<george_barr@y...> wrote:

>
> The Cad Cut CNC plans uses a Rack & Pinion instead of a Ball Screw

or

> Acme Screw. What are the advantages and disadvantages of a Rack &
> Pinion over a Ball Screw? Any comments is appreciated.
>
> Thanks,

ACME and ball screws are prone to failure in plasma enviroments
unless care is taken in making the units clean.

Also, rack is faster than ball screws. Typically a rack is one
recolution per inch or maybe 2 inches per rev. Ballacrews can be 2
revs per inch.

For some work, the rack is the first and best choice, for others it
is a ballscrew. And for others it is a compromise either way.

For long tables, say a 14 foot table, the ballscrew has to be huge or
it will whip around on rapids. for the same table, a small rack
might work if the table is non-contact.

Ballscrews are more precise and racks are easier to clean.

I think the best thing is to figure out the table first and then the
means of driving it.

Dave