Re: [CAD_CAM_EDM_DRO] servo question

My .02 worth.
I just tried to do exactly that (control cnc servos off my DRO setup).
Big problem with the backlash:{( The motors would just sit there and
"dither" because the encoder was attached to table movement and not servo
movement due to the backlash.
To even make it work, I had to really tighten up on the backlash
adjustments and even then, there was a problem. I finally resorted to
moving the encoders and now it is happy and works very well.

Bubba

At 11:04 AM 2/13/2004, you wrote:

>Hi,
>
>Yes, what you ask is possible but is probably a complete waste of time
>without very high resolution scales. A servo motor has the encoder either on
>the leadscrew or, more often, the back of the motor.
>
>If we assume you are using 5 threads/inch leadscrews with a reduction of 3:1
>gearing of the servo to leadscrew and an encoder of 400 cpr this would add
>up to many more pulses for positional control than could be derived from the
>linear scales of a DRO. I would think it possible to acheive a DRO from the
>product of a servo rather than servo control from a DRO. However I have not
>looked into doing this and I don't think this question has ever come up on
>this list before.
>
>Regards,
>
>Terry
>
>
> > If a servo system is basicaly DC motors controlled by positional
> > feedback
> > could you not use DRO's for this to drive DC motors or is there a
> > fundimental flaw in my thinking?
> > If I am right is there a particular software/hardware system that
> > would facilitate this best
> > Could I still get a visible readout?
> > Would a particular DRO be better to facilitate this
> > waiting your answers with baited breath
> > emconut

Bubba

OLDER THAN DIRT
Country Bubba
(Actually the inventor of Country and Bubba)
In God We Trust

axtein@...
LaGrange, GA

http://ns1.dicomm.net/~axtein/dro


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