Re: [CAD_CAM_EDM_DRO] SeriesII Quill Zaxis CNC addon ideas: Like Jon E's?

Tim,
Thanks for pointing out the screw wear problem to me. I hadn't even
considered it, but it makes sense if you think about the constant
up-and-down in almost the same area on the screw. I was pointed to some
pictures the other day, at http://www.motovidia.com/MILL%20pics/, which
showed a Z axis knee, with a ballscrew, and to keep the knee from falling
through gravity, he had to mount a 150 lb. gas spring from the knee to the
base, to balance it. I wonder if the tendency of the knee to fall, can be
overcome by using a ball screw with a greater number of TPI?

Marv Frankel
Los Angeles

----- Original Message -----
From: "Tim Goldstein" <timg@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, November 21, 2002 4:43 PM
Subject: Re: [CAD_CAM_EDM_DRO] SeriesII Quill Zaxis CNC addon ideas: Like
Jon E's?


> Marv,
>
> The only downside of doing it with an acme screw is the wear. Carrying
that
> much weight and moving it all the time will likely yield an inconsistent
> pitch in a relatively short time. Besides, on my machine it was already
> equipped with the ground screws from the factory.
>
> Tim
> [Denver, CO]
> Sherline products at Deep Discount (now Mach1 CNC controller too)
> www.KTMarketing.com/Sherline
>
> ----- Original Message -----
> > Tim
> > If you size your motor properly, with the right gearing, is it
> really
> > necessary to convert the knee to ballscrew? It seems to me, with that
much
> > weight on the screw, the original acme screw would have virtually no
> > backlash. Gravity would take care of it. If we could figure out how to
put
> > the same amount of tension on the x and y axes, we would probably never
> have
> > to concern ourselves with their backlash. Aren't we doing almost the
same
> > thing with pre-loaded nuts?
> >
> > Marv Frankel
> > Los Angeles
>
>
>
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