Re: A little experiment on demagnetization

Hi Mariss,

A couple of questions. As you may know I'm trying to figure out why
I'm not stepping on some E-bay special motors.

From a suggestion, someone said to read the demagnetization threads.
I know this topic is somewhat stale, but after reading the thread, I
have a question as to the motor and another as to terminology.

First question, assuming your original steppers were modified to
bring the wires out the front, we might assume that the steppers were
fully disassembled. therefore a 20% to 50% drop might have occurred
at that time. Then sometime latter, you test these already modified
motors which are under spec, but have remained assembled for some
time. You then disassemble one of them. A further drop in power is
then recorded. subsequent disassembly(ies) in close time proximity
(hours or days) does not show any substantial power loss.

what happened in between the original time they were re-worked and
the time you disassembled them ? Was there a partial magnetic regain
of some sort ? It might be that the original loss was only 20%, or
it might have been 50% with some change over time.

I know that answer can only be divined, or found after years of
testing. But it does beg to be addressed.


The whole thread discussed loss of magnetism, but did not mention how
it is lost. Faced with the possibility of having a half dozen bad
units, this is of concern to me. Is magnetism lost over time on a
shelf ? or in use ? by higher voltage/power ? and disassembly?


One question that was repeated, that no one picked up and ran with,
is "are there any shops/people that re-magnetize?" I don't know if
you have that answer, but I was hoping someone in our vast audience
does.

Second question, this is about terminology.

> 6) A parallel connection halves the voltage drop compared to a half
> coil connection.

*************************************************************
I thought Parallel WAS a half winding ? If I remember, you mentioned
that your motors were 6 wire, so unlike an 8 wire, the only choices
are half coil or full coil.
*************************************************************

> Parallel connected, you would have a 1.125V advantage over a half-
> winding motor. The ideal motor would then "see" 43.875V versus

42.75V

> for the half coil connection. The half coil would "see" 97.4% of
> parallel connected voltage, a 2.6% difference.

<snip>