RE: Ballscrew installation issues

Chris wrote

Unless anyone knows an economical source of round rather than square
nuts for 5/8" screws.

My "Rockford Ball Screws CO." are 3/4" but they have round nuts with external ball tubes. I would check to see if their 5/8" nuts are the same style. If so you can save plenty of space. 815-874-9532 fax 815-874-7897 I don't know if they are on the web?


Is there any standard trick for making up double preload nuts from the
single ones? I was thinking of making two pieces to thread onto the
end of the nuts that could somehow be rotated in relation to each
other to set preload and then clamped. Should there be a spring of
some sort in there, or just the springiness of the metal involved?

Again my Rockford nuts have a bevel spring between the nuts along with a threaded collar to tighten the spring. Not much movement, but plenty of pre-load force. I don't know how much pre-load, I just tighten it until it feels about the right amount of drag. Not very technical, but that is what I have been doing and it seems to work fine.

What size (series/pitch) timing belts are people typically using?
With a .200 lead screw and a 200 step/r motor I need 2:1 reduction
just to get steps of .001, but am planning on going for .0005 or
.00033 if I use a 10 tooth driving a 60 tooth. I'm thinking of buying
a single 470-oz/in or so stepper to try on the crosslide and
eventually leadscrew.

If you get micro-stepping drivers the result will be finer resolution. A 1 to 1 ratio with a 1/8 step driver will give you .000125" per step resolution. A 2 to 1 reduction will give you more torque, but may reduce the top speed. There are many factors which determine top speed.

Charles Hopkins