Re: Acme / Ball Screw conversion

Tom,

FWIW, literally hundreds of mill/drills have been converted to cnc
using 5/8 diameter ballscrews... And are operating successfully.

1/2 is just a bit small, IMO

Is 3/4 better? Well, of course. But do you need to wait for one, or
would you rather just use a 5/8 you can get new for near a used
price? (The rh 5/8-.200 is the single most popular size ballscrew; so
price is very good )

Hope this helps,

Ballendo

P.S. The 1 inch size is the second most common; so why not "match"
what you have on y?

--- In CAD_CAM_EDM_DRO@y..., "mayfieldtm" <mayfiet@i...> wrote:
> OK... Jon, Ray and Ballendo!
>
> Now I would have never thought of the compressive thing, even
though
> I've seen the tables in the catalogs.
> Just goes to show, it never hurts to ask the experts.
>
> Now that I'm scared straight.
> I think it is probably best to save this screw for my little lathe,
> and wait for the opportunity to finagle a 3/4" setup.
> I don't think I have room for much larger.
>
> Actually I am using step motor drives and I have retrofitted the Y-
> axis with a 1" ball screw.
> You see, a bit here and a bit there.
>
> I opened my Danaher Linear catalog to the "Compression Load" Table
> and let my finger do some calculating.
> A 1/2" x 30" screw with my Ball Nut and Rigid Mount on both ends ~=
> 1500 lbs. Max. Compression Load.
> A 3/4" ~= 7000 lb. Max. Compression Load.
> A 3/4" screw, with Rigid Mount on one end only ~= 3000 lbs.
> I would guess that using tension such as Jon suggested, the tension
> amount would be directly added to the above loads.
> These numbers look really good to me, or because of my empirical
> nature, actually don't mean a heck of a lot either.
>
> Is 1000 lb load on a small mill considered norm?
> So what do you think?
> Would you consider a 3/4" screw to still be on the flimsy side?
>
> Tom M.