Re: [CAD_CAM_EDM_DRO] Steppers vs Sevrvos?

Thank you all for you info with regards to this post.

I think I will stick with steppers for the time being, as the project is for 7x12
mini lathe the servo route may be a bit of an overkill!

Steve G.

JanRwl@... wrote:

> In a message dated 06-Aug-01 19:36:02 Central Daylight Time,
> cnc@... writes:
>
> > What are the +'s of Servos over Stepper motors and vice versa?
> >
> >
>
> Steve! Try as I might, to come up with an "adult response" to this valid
> question, I find it difficult! So, forgive, if I am frank: Servos require
> more discipline, and much, much more smarts than I will surely EVER have!
> Steppers can be applied with amazing success with no more than "reasonable
> care and workmanship", and will "do the job" very, very well for many, many
> CNC applications. Stepper-systems, done well, are less expensive, less
> complicated, and easier to comprehend, for a learning-challenged old
> [deleted] like myself.
>
> At least "theoretically", a properly-configured servo system "always knows
> what movement has (not) taken place, so, "lost steps" are not an issue. The
> servo system is "close loop", meaning there is a shaft-encoder to "feed back"
> the position information to the controller (computer, etc.), so, if something
> should "snag", the machine will "keep on trying" to get where it was headed
> before commencing further moves in the program. However, a stepper-system is
> "open loop" - meaning that the signal (power) goes only from the controller
> to the steppers, and there is no "closed loop" to return the "information" to
> the controller, so, it never "knows" what movement has (not) taken place.
> So, were there a "snag", etc., the program would have skipped steps, but
> would keep on doing its thing, as if no problem had occurred (since it "never
> knew"). Thus, an expensive part, and often the machine itself would be
> damaged, if not totalled, due to an "everyday kinda snag".
>
> HOWEVER... Many, many earlier CNC machines, and the little ones I build are
> "steppers-only, open-loop", and, as they operate "within known confines",
> they are perfectly reliable. To know which, when just simply takes years of
> "doin' it"!!!
>
> Lotsa luck!
>
> Next question?
>
> Jan Rowland, Troll
>
> [Non-text portions of this message have been removed]
>
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