Re: [CAD_CAM_EDM_DRO] help!

In a message dated 26-May-02 16:40:49 Central Daylight Time, mabw@...
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



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