Re: [CAD_CAM_EDM_DRO] Re: Vertex Rotary Table Backlash

In this case, why not to build rotary table driven by the belt/chain
directly from
stepper, with no worm gear involved?
Alex

----- Original Message -----
From: bazer_20002000 <b.smith@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, May 26, 2003 3:23 PM
Subject: [CAD_CAM_EDM_DRO] 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
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...,
timg@...
> Moderator: pentam@... indigo_red@... [Moderators]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>