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IndustryArena Forum > General Maintenance > SERVICE FOR CNC-MACHINES > CNC stepper (?) motors have power & signal but won't move
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  1. #1
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    Jan 2006
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    CNC stepper (?) motors have power & signal but won't move

    Hi all, I am working on a very simple, basic CNC router, which has been sitting for a year. I watched it being run last November, but I haven't previously operated it myself. I've got it hooked up to the same Mach3 installation as before, with the same profile.

    When I try to jog either axis in Mach3, the motor makes a noise as if it is trying to turn, but it does not turn. This is the case for all 3 axes. MDI input also produces motor noise but no movement, and the noise continues until I hit the e-stop, presumably since the gantry is not moving the input of it reaching the desired position isn't getting sent back to the controller, so it keeps trying to move.

    When power is off I can push the X and Y axes by hand, with some difficulty but it doesn't seem unusually hard. They do both have a periodic clunk as if there's some unevenness in a gear or something, dunno if it's related to the problem. I can't push the Z axis so that may be a different issue.

    Since the X and Y motors aren't frozen, which I know bc I can move them by hand, I don't know what else to look at. Any advice appreciated.

  2. #2
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    Re: CNC stepper (?) motors have power & signal but won't move

    Hi Neal - I'm not a M3 user so can't help there. But with a stepper system there is no feedback to the controller. The controller sends out a step and direction impulse and does not know if the motor moved or not. My suggestion is to disconnect the motors from the machine so you can see the axles moving (or not) and work through the M3 config on one axis until it works. Then you can correct the other axes. cheers Peter

  3. #3
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    Re: CNC stepper (?) motors have power & signal but won't move

    Hm, OK I did not know that about steppers. There has to be some kind of feedback though, as Mach3 does show position information, unless it is calculated.

    I am currently guessing that it's not a Mach3 config problem but a mechanical problem with the motors. It probably does make sense to disconnect one and check it without trying to move the whole axis tho.

    Thanks

  4. #4
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    Re: CNC stepper (?) motors have power & signal but won't move

    Hi Neal - sorry no feedback at all, zero, nadda, zip. The DRO only counts the controller steps and assumes its correct. If the motor skips a step due to an overload that skip exists until you re-zero the machine. So everything past that skip is wrong.

    Unlikely to be a motor problem, steppers are very robust. Easiest way to kill them is to drop them on concrete. Electrically really really difficult to kill....I've tried all sorts of ways to cook them, unsuccessful so far except the drop thing that was an unhappy day...Cheers Peter

  5. #5
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    Re: CNC stepper (?) motors have power & signal but won't move

    OK I see that. I have a new problem, machine won't turn on any more, so I'm gonna have to pause this issue until I fix that one, yay. Hopefully just a bad switch. Thx for your help.

  6. #6
    Community Moderator ger21's Avatar
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    Re: CNC stepper (?) motors have power & signal but won't move

    When I try to jog either axis in Mach3, the motor makes a noise as if it is trying to turn, but it does not turn.
    Try setting the acceleration about 75% lower.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  7. #7
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    Re: CNC stepper (?) motors have power & signal but won't move

    Quote Originally Posted by nealscnc View Post
    Hi all, I am working on a very simple, basic CNC router, which has been sitting for a year. I watched it being run last November, but I haven't previously operated it myself. I've got it hooked up to the same Mach3 installation as before, with the same profile.

    When I try to jog either axis in Mach3, the motor makes a noise as if it is trying to turn, but it does not turn. This is the case for all 3 axes. MDI input also produces motor noise but no movement, and the noise continues until I hit the e-stop, presumably since the gantry is not moving the input of it reaching the desired position isn't getting sent back to the controller, so it keeps trying to move.

    When power is off I can push the X and Y axes by hand, with some difficulty but it doesn't seem unusually hard. They do both have a periodic clunk as if there's some unevenness in a gear or something, dunno if it's related to the problem. I can't push the Z axis so that may be a different issue.

    Since the X and Y motors aren't frozen, which I know bc I can move them by hand, I don't know what else to look at. Any advice appreciated.
    It sounds like possibly the polarity of the wiring could be reversed. Try switching 2 wires on one phase. I had a similar problem and that fixed it. If the motor turns, then you'll need to change the direction for that motor in machine. Good luck!

    Sent from my SM-T860 using Tapatalk

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