Stepper motor 101 was Re: Are steppers considered low frequency motors?

Hello,

IME Linisteppers work fine in their "designed-for" applications...

They really are meant for 1Amp motors and telescope drives where
smooth smooth motion is desired at low--and relatively constant--
speeds.

Having said that; I've used a few in CNC apps with 2 amp motors
without a hitch.

IMO they're great for learning about--and messing with--
PIC "stepper" code, and while the heatsink and power supply
requirements are bigger than for chopper drives; they are still
inexpensive and user repair-able.

ALSO, the Lini- is NOT linear stepping; but linear amperage/winding
control.

The STEPPING waveform is stepped, just like other drives. What might
be causing the confusion is the portion of James Newton's website
devoted to the linistepper which promotes the idea of a "stepless"
drive. AIRC what he's doing is adding capacitors? to SMOOTH the
transitions between the STEPS of HIS simulated-sinewave waveform
(like the ones I mentioned originally. The idea being that this is a
way to make a "better" simulated sine wave; an "innovation".)
Personally; I just ignored that part, and used the linisteppers as
linEAR CURRENT CONTROLLiING stepper drivers.

For this, they work as advertised and represent a very inexpensive
way to get microstepping drives of "high" voltage capability; albeit
at lower amperages (IMO James covers this well at his webiste, which
is extensive in its description and considerations for using the
linistepper drives)

It's only fair to add that the SLA chip based drives DO seem a better
choice nowadays for most CNC uses. At the time I bought the
linisteppers--and spent time telling others they were a good choice--
the HCNC ond other Sanken chip based drives were not yet
available.

Ballendo


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dennis Schmitz"
<denschmitz@...> wrote:

>
> I think you should avoid it. Way too much loss in the transistors

and

> the idea to use linear ramps misses much of the theory. A stepper

used

> as an synchronous AC servo needs a sin/cos signal or it won't have
> smooth torque through the steps.
>
> On 8/9/06, Alan Marconett <KM6VV@...> wrote:
> > Hi,
> >
> > So what about Linistepper?
> >
> > http://techref.massmind.org/techref/io/stepper/linistep/index.htm
> >
> > Appears to be an attempt to do a linear ramp (triangle?) to drive

a stepper?

> >
> > Alright, it's got a PIC on it (I like that), but I see two BIG

resistors,

> > for a unipolar driver.
> >
> > If we really want a sine wave, why don't we just use a linear amp

and drive

> > it with a sine wave? Class A (B? even C?...) Wastes too much

power I'll

> > bet.
> >
> > Alan KM6VV
> >
> > > ballendo:
> > > In half-stepping we do a little better job of approximating the

sine

> > > wave, because we turn one OR two coils on at a time. This puts
> > > a "step" in the simulated sine wave, so it looks a little more

like a

> > > complete sine wave. (Very little actually in appearance; but

quite a

> > > bit better in performance)
> > >
> > > Microstepping is simply adding more and more "levels" of

definition

> > > to the simulated sine waves that all stepper drivers use to

create

> > > discrete steps of movement from these motors. And as the

simulated

> > > sine wave gets better; so does motor performance at slow speeds.
> > >
> >
> >
> >
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