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

Interesting on the "Master Zero Position" concept. I didn't think of that, if
it is out there. Could be made I suppose even using a real basic technique
like one very accurate switch somewhere in the rotation. But, then you would
have to orientate the part correct to that switch to start with. The next
issue with that is making sure that we can get the under $1k PC based
controls to handle the "searching/indexing" necessary to know where 0 is on
that part.

Servo Experts ? Anyone?

Chris

Fred Smith wrote:

> > There is still the problem reseting the piece to zero. I think this
> > could be handled by turning off the power and rotating the shaft by
> > hand to a known position. A fixed position could be established by
> > resting an arm, attached at a right angle to the 4th axis shaft, on
> > the top of a 1-2-3 block or some such.
>
> If you add in a spindle brake, and an encoder on the servo, you have
> a full blown C axis on a lathe. Don't encoders have a master zero
> position? Gross/rapid position to a rotary position that is detected
> by a photo sensor, and then slowly fine position to the "big" mark on
> the encoder. Absolute zero degrees. No mechanical parts to wearout
> or misalign. Just the brake. If it's a lathe with CNC threading
> capability, you probably already have most of what you need to zero
> out the rotary axis.
>
> Best Regards,
>
> Fred Smith
> IMService
>
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