Re: [CAD_CAM_EDM_DRO] Re: 8-wire stepper motor

That's how I solved the same problem. It helps if you wrap a piece of scotch
tape around the shaft to make a crude "pointer" and mark in pencil each
position where the motor stops. You'll need a sharp pencil. You will find
that the coils work in pairs so that forward and reverse current moves the
motor to the same two positions for both coils. These coil pairs can be
connected in series or parallel for bipolar operation, or use a common V+
for unipolar operation, where grounding either of the remaining two wires
moves the shaft in the opposite direction of the other.
--Phil M.

----- Original Message -----
From: "jacoby01" <BobJacoby@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Sunday, February 19, 2006 2:36 AM
Subject: [CAD_CAM_EDM_DRO] Re: 8-wire stepper motor


> Sorting out the wires on an 8-wire stepper motor:
>
> Dave, I make no representations that this is correct, or safe, and
> I'd love to hear feedback from others, but on small stepper motors -
> say NEMA size 23 120oz steppers, I just sit down with a 6-volt
> lantern battery and power up successive pairs. What happens is that
> you'll first discover which one of each pair should be a common
> ground because the motor will step in the same direction when you've
> randomly selected the correct polarity for each. Restated, if two of
> the pairs (keeping track of which one of each pair you hooked to
> ground on the battery) turned the motor clockwise, and the third pair
> that you try turns the motor one step counterclockwise, then switch
> the third pair (ground verse positive) and move on to the final
> pair. After you've figured out the ground for each pair using this
> method you then sequence the pairs until you discover which sequence
> of pairs causes the motor to step smoothly. There will only be one
> sequence of pairs (again using the grounds the you identified in step
> one)that cause the motor to move smoothly.
>
> Note: - each of these "test" causes the motor to only move one step,
> but that is enough motion to be able to correctly identify the
> pairs. Also, this whole process takes less time that it took to
> write this e-mail.
>
> Let me know if this works for you, and I'd love to hear any comments
> from others on this method.
>
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