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wild discovery with stepper

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  • wild discovery with stepper

    Hi all. Working on my BP pc conversion and had a problem with a stepper. These are new steppers and I have to remake the mounting .I machined the original housing and made an adapter plate for the stepper.Modified the cog pulley as per the earlier post.Mount it up and the stepper felt like it was bad.It turned ruff and grabbed. Me is thinking good thing I didnt cut a keyway in this thing and void the warranty.

    Take it off and it turns free. Put it back on and it is ruff sometimes and then OK. I take it off and email Kelig about the problem,.

    Get a reply.Says to connect all the wires together then disconnect.Should be fine then. I do that. Hook them together and try to turn the stepper.Wont budge.Remove the wires from each other and its ok.I think when I was mounting it the wires were still all tied together in a bundle.I think they must have been touching the bare ends as I installed it and caused this problem,. Wild huh!



    Keling said touch wires together to remove magnetism and run it. OK : )

  • #2
    Now get one motor and connect it to another, wire colour for wire colour, then turn one motor by hand and watch the other

    .
    .

    Sir John , Earl of Bligeport & Sudspumpwater. MBE [ Motor Bike Engineer ] Nottingham England.



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    • #3
      This doesn't make any sense. What could connecting the various wires of a stepper motor that is unpowered possibly do to it, either good or bad. You speculate that possibly connecting the wires during assembly caused it to act up and then deliberately shorting them caused it to get better. ?????

      Did they tell you to apply power in some manner or to spin it after shorting it or what?
      Paul A.
      SE Texas

      And if you look REAL close at an analog signal,
      You will find that it has discrete steps.

      Comment


      • #4
        What is being talked about is because a stepper is a perm magnet motor with windings it will function as a generator if spun over. If wired pin-to-pin to another motor, the second motor will turn in step as the first motor is turned.
        If a winding on a single motor is shorted at its output leads the motor will resist turning and is quite noticable. I seen this behavior when I did my bridgeport conversion. I too initially thought I had a bad motor by the way it felt when turned by hand unwired, it turned out to be caused by 2 wires that were touching on the bench. Marris (?) at Gecko drives gave me a quick tutorial on this behavior.
        The power these modern steppers can generate for their size is quite amazing.

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        • #5
          Still doesn't make sense. They told him to connect all the wires. What does that do? Apparently it will stall it. Then disconnect them. That's the only part that makes sense.
          Paul A.
          SE Texas

          And if you look REAL close at an analog signal,
          You will find that it has discrete steps.

          Comment


          • #6
            Originally posted by Paul Alciatore
            Still doesn't make sense. They told him to connect all the wires. What does that do? Apparently it will stall it. Then disconnect them. That's the only part that makes sense.
            They were telling him his problem was shorted leads by providing an exaggerated scenario where all leads are intentionally connected. Wiring two motors together provides a motor-generator pair and the driven motor will track the driver motor perfectly forward and backward.

            Decca used to make a radar for small boats that drove the scanner/display this way. The scanner had a motor and a generator geared together. The output of the generator is multi-phase and drove a small motor in the display unit that rotated the deflection coils in the display. A heads up switch synchronized them for position so the display and antenna both pointed in the same direction, and the motor/generator set remained aligned thereafter.

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