Re: [CAD_CAM_EDM_DRO] Rong-Fu RF-45

On Sun, 30 Jul 2000, you wrote:

> This question is directed toward Dan Falck, or anyone who has played
> with an RF-45. I recently aquired a nice set of NSK ball screws from
> Bill Giffin and am ready to start my conversion to CNC.
> I'm wondering if you used commercial end supports with ball
> bearings or made your own. I'm curious about the preloading of the
> screw and how you approached it.

I am using the original ball thrust bearings that came with the machine on the
right side of the table. On the left side, I bored it out and pressed in a
bronze bushing. In my parts box are a couple sets of Timken roller bearings
that I have been planning on putting in to replace these. To adjust preload,
there is a 1/4"-20 socket head cap screw with a driver thimble in the end of a
piece of tubing that the timing pulley is attached to. The timing pulley has
two set screws in it. One is tightened onto the tube and the other goes through
a slot milled in the tube and rests on a flat spot milled into the ballscrew.
Adjusting is done by slightly loosening the set screw that is on the ballscrew
and then tightening the 1/4"-20 cap screw. Roland has plans for this that you
can get from Cardinal Engineering. I don't know if I can describe how much to
set it for- I just tighten a little, then run the machine, and measure.
Sorry for the poor description, but I think Roland's plans from Home Shop
Machinist are the best thing to check out.

Dan