Re: [CAD_CAM_EDM_DRO] Re:Re: Re: 4th Axis Concept (long)

Ian......... You got it !

If this is done correctly, who says the part has to be "round" at all ?? It
could be a typical rotary indexer plate capable of continuous rotary motion at
higher speeds with Anything mounted on it. (watch for out of balance conditions)

It looks like the Servo arrangement, Single optical or Single Proximity switch
is the best method, however, I still think I may work on a mechanical solution
via stepper activation.

Why? Because of the existing market already using Sherlines, Taigs, Etc. under
Stepper control.

Mr. Al, from a previous message, has described a very good way to do this with a
Sherline lathe. Lots of Sherlines out there.... more in the future I'm sure.

Thanks to all who contributed,

Chris L

Ian Wright wrote:

> Hi Allan,
>
> You may wnat to index to a 'home' position for a number of reasons:-
> 1. Unless you are certain you can complete all the job in one session you
> may want to restart from a known position.
> 2. The part you are working on may have mounting holes, lugs etc which need
> to be in a fixed relationship to your work - for example, you may want to
> engrave a number of decorative, engine turned bands around the top of a
> coffee pot, stopping just short of the spout either side.
> 3. You may need to take the work off the machine for some reason part way
> through the job and then replace it.
> 4. You may want to do a bit of engine turning, then a bit of plain turning
> and then more engine turning on the same workpiece - say because you forgot
> to reduce the diameter of the second bit of decoration before you mounted
> the job. Having a fixed home position would guarantee you could start again
> exactly lined up with the first bit.
> Having said this, of course, it would depend upon the method you chose for
> homing. If you use an encoder disk fixed to the shaft and use its home
> position, you would have less flexibility but more accuracy than if you used
> an optical sensor and blade which could be set in any position in an arc
> around the spindle.
>
> Ian
> --
> Ian W. Wright
> Sheffield UK
> www.iw63.freeserve.co.uk
> ----- Original Message -----
> From: <allan_r9@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: 08 August 2001 05:06
> Subject: [CAD_CAM_EDM_DRO] Re:Re: Re: 4th Axis Concept (long)
>
> > Hi Group,
> >
> > This idea was going through my vacant mind Sunday evening while
> > looking at my Enco 12x36 Gear head lathe. I originally wanted this
> > machine to try Ornamental Turning in metals. This usually involves a
> > separate powered spindle with various mechanical linkages relating
> > the chucked part position to the cutting spindle position. Indexing
> > the part in the chuck is a very common move during OT, so I was
> > imagining a large stepper with something like a 1:5 pulley reduction
> > with the large pulley mounted to the tail end of the spindle. I was
> > thinking of a mechanical tensioner for the belt, and that the belt
> > would be removed for normal turning. As to indexing, why have the
> > spindle travel to a home position? Since the chucked part is 99% of
> > the time round, why not just zero out the spindle axis and start from
> > there? If the part is odd shaped, locate the chuck to the position
> > you want, then zero the axis anyway? Long in the future, this will
> > be a conversion job, after the GEM500. I have the Ahha control that
> > the EMC replaced, so that should work well for this.
> >
> > Allan
> >
> >
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