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

On Sat, 28 Aug 2004 18:14:39 -0000, you wrote:

>Harvey, the motors are functioning now but still limited in terms of
>maximum speed to 20 ipm. They are bipolar in series as recommended
>by the motor factory with resistors to limit the power to 4.9 amps
>per the specs. I don't think the wiring is the problem plus these
>are high inductance motors. I would like to try to rewire but after
>cooking two Gecko drivers, I am quite reluctant except as a last
>resort.

If they are high inductance motors, the limit might be the inductance
itself. You might just try using half the winding. The current
should not be a problem with the geckos, and the lower inductance
might help the speed. You will get fractionally less torque, but the
speed improvement would offset that.

Your choice, though, Not to want to smoke the Geckos again....

Harvey

>
>Thanks
>Keith
>
>--- In CAD_CAM_EDM_DRO@yahoogroups.com, Harvey White <madyn@i...>
>wrote:
>> 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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>http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
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