Re: [CAD_CAM_EDM_DRO] Re: Max feedrate of ball screws?

echnidna wrote:

>(snip)
>
>My machine will operate in your desired speed range. I have a counter shaft across the machine with a #25 pitch sprocket each end of my Y axis. The #42 Y axis stepper drives the shaft from the centre of the shaft to equalise torsional deflections of each end of the shaft. I feel for my purposes #25 pitch chain was the most practical method, it has a tenslie strength 860 -1000 pounds so I expect it will operate at 10 -15% of its strength.
>

Bob, Do you have a picture floating around ?? it be interesting to see
what you have "cooking" with the chain drive setup. Especially curious
how you let the chain approach each sprocket. Does it "Wrap" a little to
get more teeth into the chain at one time ??

I was thinking that this also makes adjustments for minor skewing really
easy. If you have threaded adjustments on each end of the chain, you
could simply adjust the machine to square. I suppose Plenty accurate for
most large Router needs.

You mentioned "upside down Rack:..... I once drew up a prototype Router
with Rack and Pinion, where I kept the rack Vertical on each side so
dirt fell thru it. Of course the pinion shafts were vertical, So, I ran
them straight up, joined the pinion shafts from each side up top with a
toothed belt. The Drive motor was in the middle of the gantry. It
probably would work great with some of that fancy "cable" chain from
Berg. Anyhow, it was only a drawing..... But I bet it would be smooth
and quiet.

Chris L