Re: [CAD_CAM_EDM_DRO] Vertex Rotary Table Backlash

fuddham wrote:

>I have converted my 6" Vertex rotary table to CNC. What is the best
>way to minimize backlash? What is the typical amount of the backlash
>on these tables? Also, has anyone used some sort of indexing (rotary
>table) to mount several vises on and index the vises to do several
>parts with the current tool instead of several tool changes for just
>one part then start all over again?
>
>

Assuming the backlash is between the worm and the wormwheel that drives
the table, there is a limit to what you can do. First, you may have a
mechanism
to adjust the space between the worm and the wormwheel. Some units have
eccentric bushings on the worm that allow the engagement to be adjusted.
If not, it may be possible to make new eccentric bushings. But, some worms
may be cut in such a fashion that you can't reduce the backlash to zero.
It may be possible to take a little material off the peak of the thread by
turning the worm on a lathe, to allow the threads to engage deeper.
The high-end drives use a split worm, with some kind of mechanism
between the two halves to keep a preload on them.

Jon