Ballscrews on an RF-45...

Hello:

I'm CNC'ing my RF-45, and starting with the ball screws.

It seems most are using the 0.631 ball-diameter (0.615) size
screws from McMaster Carr or Reid Tool. These nuts are under
$25.00 each, and the screws are cheap. The next size
(3/4 inch or so) is more than twice the cost.

Is this really big enough? My ACME screws that came with
it are about 7/8 (or 1", I'm not certain.) I've heard the
controversy saying that these thin screws are only good
for very short shafts (like lathe z-axis) but not only are
larger more expensive, but they don't fit in the allowed
space well.

Does anyone with "experience" have comments. I know, in a
perfect world, I'd aim for 1" ball screws.

Also, is there any good online source for single-quantity
ballscrews and nuts other than the two above sources? I
like web sites that actually have prices, and will sell
without a minimum quantity.

- tj.