Re: fickle y-axis

Hi Jeff, others,

Somehow I still don't understand how my stepper should move in
undetermined direction when 1 phase B is out. Below is an attempt to
show a stepper after phase A had just been activated, in which case
the rotor would be attracted to the nearest opposite pole. In a half
stepping configuration This would would be followed by AB, then -B in
which case nothing happen. The next step would be A'- when the pole
would reverse polarity (in a specific sense determined by the command)
........(A)
.........N.............
.......................
..B......S........B....
.........|.............
.........|.............
s........x............N(A)
.........|.............
.........|.............
.........|.............
...B.....N........B....
.......................
.........S.............

The diagram below would show phase A polarity reversed. This would
show the rotor been moved in a very specific sense, definately not
indeterminant.

........(A')
.........S.............
.......................
..B...<--S........B....
.........|.............
.........|.............
N........x............S(A')
.........|.............
.........|.............
.........|.............
...B.....N-->.....B....
.......................
.........N.............

Could it be the reason for the erratic behaviour was due to something
else?

Anyone had any experience with the wire for 1 phase broken? How did
the motor behave?

Peter


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "jeffalanp" <xylotex@h...>
wrote:

> Hi Peter,
> Yes, all 100 poles are activated; they are all wound with the
> same wire.
> Best bet would be to find a cheap (or broken) stepper motor and
> open it up and take it apart (which can ruin it). On a small

motor,

> you will see the rotor has two different sections, one slightly
> offset from the other (A and B). You can also 'see' the 'poles' on
> the rotor.
>
> Jeff
> http://www.xylotex.com
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "forumtvm" <forumtvm@y...>
> wrote:
> > Hi,
> >
> > Just one small question. In a stepper motor with 100 poles for
> phase
> > A and 100 poles for phase B, when say phase A is activated, does
> all
> > the 100 poles get magnetised. I suspect this is the key I need to
> > grasp before I get to understand why my y-axis got to behave so
> > erratically when one wire got loose/disconnected.
> >
> > Peter