Re: [CAD_CAM_EDM_DRO] quill drive

GRautoHP@... wrote:

>I need a good z axis quill drive for my bridgeport clone. any leads?
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We're talking about a CNC axis drive to move the quill? This is not
a simple problem. Unlike the X and Y, which already are set up for a
leadscrew to drive them, and therefore pretty easy to retrofit for CNC,
the quill of the manual Bridgeport is not. The rack and pinion is useless
for any sort of precision. And, the shape of the head makes it difficult
to get a leadscrew close enough to the quill to move it without some
bending of the linkage. But, my best advice is to keep the leadscrew
absolutely as close to the quill as you possibly can. Most systems use
some kind of linkage to where the stop ring is bolted to the front of
the quill. I did this, and have the ballscrew about 2.75" from the front
of the quill. I made as massive a linkage as possible, and I have a fairly
stiff quill (it was jammed and rusted in place when I got the J head).
But, I get only about .0015" of backlash, mostly bending of the linkage,
and maybe some bending of the ballscrew, too.

I bolted a frame that supports both ends of the leadscrew to the holes and
bosses on the main casting that the stop rod passes through.

Jon