Re: Jan....opening steppers can......

RC,

Do not open a step motor. Especially do not remove the rotor from the
stator. The stator acts as a "keeper" for the rotor magnets, removing
the stator will de-magnetize it and thereafter the motor will be a
drive killer because the inductance will be very low.

Another reason is unless you have a clean room enviroment, the rotor
magnet will find that microscopic steel chip (chips) on your bench
and incorporate it in the .003" air-gap between the rotor and the
stator. You will not be able to remove them even if you could see
them without dismantling and demagnetizing the motor.

At their invitation, this Thursday I am flying up to the Bay Area to
meet with and tour the facilities of a major step motor manufacturer.
I will be asking questions. If I learn anything new or interesting on
this or related subjects, I will post it here.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "RC" <asdf@c...> wrote:
> You say opening up a stepper can trash them, does it de-magnetize
them?
>
> RC
> ----- Original Message -----
> From: <JanRwl@A...>
> To: <CAD_CAM_EDM_DRO@y...>
> Sent: Sunday, May 26, 2002 3:41 PM
> Subject: Re: [CAD_CAM_EDM_DRO] help!
>
>
> > In a message dated 26-May-02 16:40:49 Central Daylight Time,
> mabw@b...
> > writes:
> >
> >
> > > The stepper motors I have are 3 volt , 4 amp 6 wire jobs and I
want to
> get
> > > the most torque out of them with no real concern about fast
feed rates
> so ,
> > > do I wire them as 4 wire leaving the center taps vacant, if so
what is
> the
> > > resistor value required? or do i 4 wire using two end taps and
the two
> > > center taps , again what size resistor? I know the guide that
came with
> the
> > > drives does explain it but as I am so hopeless with this stuff
that i
> would
> > > rather ask the experts than stuff the drives!<<
> > >
> > Mark:
> >
> > I hope FOR YOU that Mariss will answer this question
specifically! What I
> > suspect is that these are MO92-FD08 S.E. motors (or equiv.). I
think
> Mariss
> > will tell you to use the "center tap" and one end, insulating the
other,
> for
> > "ONE phase", and LIKEWISE for the "SECOND phase", but if speed is
not a
> > problem, you might get a TINY bit more torque by using "ALL the
copper",
> by
> > using only the ENDS of each winding, insulating the "center
taps". This
> will
> > increase the inductance FOUR-fold, I think it is, and make the
possible
> > stepping-rate MUCH lower.
> >
> > As to which current-limit resistor to use, Mariss will have to
instruct,
> as I
> > never had to USE a "six wire" on a bipolar drive, so I have
ignored the
> > "rules" about current for "half coil" and "full coil". It is NOT
the
> same,
> > and I understand, and all, but I did not memorize the "math".
Duh...
> Sorry!
> >
> > Sadly, opening a stepper can severely damage its specifications,
if not
> total
> > it, but "in theory", at least, if you could examine the
connections
> inside,
> > to the "inside ends" of those center-tap lead-wires, and
separate, and
> > bring-out BOTH (if two), then, you'd have an EIGHT-WIRE motor,
and you
> could
> > parallel pairs and have a "100%" 4-wire bipolar motor! But
consider this
> > ONLY if you can afford to TRASH the motors in question, and have
more to
> use!
> >
> > Bipolar rules!!!
> >
> > Regards! Jan Rowland
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
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> >
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reach it if
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> >
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> >
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