Re: [CAD_CAM_EDM_DRO] stepper vs. servo

Steppers are an open-loop system. Faith based, if you will. In nearly
all systems, the computer tells the stepper to move, and assumes that
it has. Servos, being closed-loop, will go where they're told, or let
you know about it.

I would go for the servos. Steppers are what you use when you can't use
servos, for whatever reason, such as cost, size, know how, etc.

Regards,
JJ

p.s.. Steppers have brushes too. I have machines running 5 to 7 days a
week, from 1 to 3 shifts, and (servo) motor life is measured in years.

On Monday, Feb 9, 2004, at 15:57 US/Eastern, plastiguy wrote:

> Group -
> I'm going to go ahead and open up this can of worms (though I'm
> certain it's been done many times before my time in this forum). The
> age old question has popped up again. For a 4x8 CNC router with
> pretty standard mechanics I can effectively use either steppers or
> servos, each of which I can readily find within the torque range I
> need (400 to 600 in-oz, about 200 watts max), and each of which I can
> use with my driver of choice (Gecko G320) and each of which fit
> comfortably into my budget and each of which are addressable with my
> software of choice Mach 2 AND each of which offer the resolution
> (depending on manufacturer) I desire. So, I'm finding it more and
> more difficult to commit one way or the other. Given these equalities
> for my specific application, I'm beginning to think that in the end,
> from a performance and features standpoint, there'll be no
> significant difference. Oh sure, I know the stepper-advocates will
> point to the consumable brushes on the servos, and the servo-camp
> counters with...well, something equally relatively minor, but are
> there big glaring pitfalls and upshots for these different means of
> moving junk around that I'm missing? I'm a believer in "You get what
> you pay for" so I don't want to sacrifice anything important just to
> save a few bucks and go with steppers, whle I also don't want to
> throw money away by integrating servos when, once the covers are put
> on the machine, I'll never even detect the difference in having put
> the servos on instead of the steppers.
> Hope I'm missing something so I can GET ON WITH IT!
> Scott
>
>
>
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