Re: Vertex Rotary Table Backlash

Hi Im not familar with the Vertex system however you could consider
junking the worm wheel and fitting an adjustable zero backlash unit
(ie the worm wheel is split down the middle). These can be costly
but this depends on the size needed and how much you want to cut any
backlash out.
Barry

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Andrew Mawson"
<andrew@m...> wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...>

wrote:

> >
> >
> > 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
>
> fuddham,
>
> On my 4" Vertex I stripped it right down, cleaned out the road tar
> that they seem use as a lubricant, re-oiled it, and set the

eccentric

> bush so that I could just feel the high spot when turning by hand -

> this brought the backlash down to 'reasonable' but I haven't

measured

> what 'reasonable' is.
>
> I seem to remember it being suggested (?? by Tony Jeffree??) that

it

> is worth 'running in' by mounting it so the lathe or some other

power

> source turns the worm & wheel while meshed to bed them together.

This

> will take off the highspots and let you get a lower backlash

figure.

> Logically, as the running in progresses you should adjust the mesh
> closer - I suppose its a sort of lapping action.
>
> BTW I like your idea of multiple parts being processed while the

tool

> is still in.
>
> Andrew Mawson
> Bromley, Kent, UK