Re: [CAD_CAM_EDM_DRO] Re: Re: Re: Can CNCPro users provide some input?

Ray,

I realize that the Gecko drives and a true servo system are two different
things.
I have listened to Jon E.make this point many times on this list.
But what we were talking about is using the Kollmorgan amps with a seperate
step and direction to +/- 10V converter. That is what I was saying would be
the
same as using Gecko drives. It dosn't seem like much if anything would be
gained by using those amps with a seperate step and direction converter. You
would still be using step and direction to drive the servo amps.

Bill

>
> <s>I have some Kollmorgan +/- 10V servo amps, but the Geckos accomplish

the

> >same thing for $129.00/axis. I'll hold those Kollmorgans for another
> >project.
>
> I was wishing that you wanted to unload them. ;) But, (AND THIS IS NO
> REFLECTION ON GECKO! I LIKE THEIR PRODUCTS!) they do NOT do the
> same thing. No way! No how! Whole other world! Pardon the scream but I
> had to know that you are listening 'cause I like Mariss.
>
> Kollmorgan controls velocity, Gecko controls position. Jon has it just
> right in the post of his.
>
> <snipped from Jon E>
> The advantage to a true velocity servo, straight from the computer, is

that

> the VELOCITY is not quantized by the resolution. So, at very slow speeds,
> the motion remains smooth.
> <eos>
>
> Stepped servo motion like that produced by the Gecko 3-- series may
> well be fine for may uses, but it can not replace velocity control. The
> way most machine tool builders are getting around this and using digital
> signals like step and direction is by using very high resolution count
> encoders. I've replaced units that spit out 250k ppr and have heard of
> encoders that put out 1M ppr. Big bucks! These kinds of position
> resolutions will approximate velocity control using drives like the Gecko
> but they will not equal it.
>
> And the 320 geckodrive has a max step rate around 250 Khz which would mean
> 60 RPM max on the encoder unit I have here. Nice resolution, but slow.
> And EMC, at least isn't near ready to put out that many pps from a pure
> software solution -- can't say about the other low cost cnc systems
>
> Ray
>
>