Re: [CAD_CAM_EDM_DRO] new stepper motors wiring mess...

On Sat, 28 Aug 2004 06:42:15 -0000, you wrote:

>Help again! My repaired motion board, replacement Gecko 210 driver
>and new stepper motors arrived. I assembled them all but installed
>only one stepper motor to the Z axis for testing.
>
>I talked to the Anaheim Automation factory person to get advice on
>the wiring for the Gecko drives and his new motor. It is wired
>bipolar in series and is rated at 4.9 amps. It is one of the new
>square Nema 42 high torque motors.
>
>There are 2 windings wired in series together on one side of the
>motor and another 2 windings wired in series on the other side. I
>was instructed to connect one end of a set of series windings to the
>Gecko phase A and the other end to Phase B then connect the second
>set of series windings to Phase C and D. This is exactly what I did
>on the original Bridgeport motor and the Gecko burned up! I told him
>this but he thought it would be correct.
>
>So on I merrily went according to the plan and it was apparently
>wrong. Luckily I had purchased a backup powersupply for the setup
>and it recognized an overload and shutdown before (I hope) ruining
>the Gecko drive. I wonder if I can just switch Phase B and C wires
>as I did before and get it to run.
>
>I just don't understand why both the Gecko instructions and the
>Anaheim Automation instructions describe the same wiring method and
>it does not work. What am I not understanding here?

If the Geckos have a problem with low inductance, you may be wiring
one of the series coils (or both) backwards. The way to check this is
to take a battery and apply it across the a/b leads of one coil only.
Note how much torque you have on the motor. Put the other coils in
series and use two batteries. You should have very roughly the same
torque. If you have no torque, then reverse one winding in the series
pair. you should get more torque.

You want the position (IIRC) that has the most torque. With the two
coils opposing each other, the inductance is low. If the Gecko does
have a problem with very low inductance motors (as I have heard), then
the two coils opposing each other creates a very low inductance.

Switching the phase B and C wires will simply make the motor run in
the opposite direction.

See if this makes sense and if it helps. Another option would be to
run the Geckos on a lower voltage adjustable supply with a current
limit, and see how the motor current increases as the voltage goes up.
If you don't have one of those, then try the previous method.

Harvey

>
>Thanks! (again)
>Keith Clark
>
>HEART FELT APPRECIATION! I think I will get to the bottom of all
>this eventually, but not without a lot of help from my new CAD-CAM-
>EDM-DRO friends! The advice, insruction and suggestions given so
>far have saved me from giving up and are truly appreciated!
>
>
>
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