Re: Z axis conversion

> >
> > Can someone point me in the right direction for info on converting
> >
> > the "Z" axis of a Bridgeport-Type mill. I'm reffering to the
> > mechanicals of getting a backlash free mechanism. Is there a worm
> > gear
> > in there or what?
>
> The hardware in the Bridgeport M and J heads is hopeless for CNC.
> There is a worm drive from the fine feed handle to the quill pinion.
> Then, the quill rack and pinion drive adds even more backlash.
> I pulled the quill pinion completely out, and drive the quill by a heavy
>
> coupling that attaches where the depth stop ring used to attach,
> through the slot in the front.

I recently got to play with an Ez-Trak CNC Bridgeport. They drive the
quill through a bracket that clamps around the end of it like a shaft
collar, reducing travel by 3/4" or so. The odd part is that this
bracket is moved by a ballscrew actuater located a huge distance (>8")
off the side of the spindle axis to the side of the head. I can't
image how it manages to move without binding, but it does fairly well.

Chris

--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
30 Griswold Street, Cambridge, MA 02138
http://www.mdc.net/~stratton
(617) 492-3358 home/shop