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Thread: Adjusting the drive pulley on a stepper motor

  1. #1
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    Adjusting the drive pulley on a stepper motor

    I need to lower the drive pulley on the shaft of the stepper motor for the Z axis on my Chinese laser. Normally I would use a sleeve and a small hammer to tap the pulley to a lower position on the motor shaft on a standard electric motor. However, I'm not sure this would be an acceptable method on a stepper motor.

    A "square key" is used to "lock" the drive pulley to the stepper motor shaft
    The drive pulley appears to be "pressed on" to the stepper motor shaft
    There is no set screw or other type of mechanical device to secure the drive pulley to the stepper motor shaft

    Is it acceptable to use a sleeve and small hammer to tap the pulley to lower the pulley on a stepper motor shaft or should another method be utilized?

    Thank you,
    Roger

  2. #2
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    Please post a photo so we can better understand what you are talking about. If it's like my Chinese stepper motor then there is no key holding the gear on only friction. So I heated the gear with a propane torch and then lightly tapped it and it slid right on. Same process in reverse if you want to remove the gear.
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  3. #3
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    The stepper motor shaft is vertical with the shaft pointed up. The pulley and the motor shaft have key ways and the pulley is "pressed" onto the shaft with "key stock" keeping the pulley from rotating on the shaft.

    I propose to tap on the pulley using a small socket (to place a somewhat even load on the pulley) and hammer to move the pulley 0.125" lower on the motor shaft.

    My question is not if the method I propose can be done or will work, but if the method will likely damage the bearings supporting the shaft in the stepper motor or the motor itself?

    If the proposed method is not advisable, what would be a method to perform this task that would not damage the bearings or the stepper motor?

  4. #4
    Rather than a hammer, do you have a vice? I'd do what you're saying except I'd put the motor, with the socket at the end of the pulley, in a vice- THEN heat the pulley- if you don't have a propane torch, a Bic lighter will work, just some flame so the pulley will expand. After it's good and warm, the vice should push the pulley down the shaft fairly easily, without the shock of a hammer--
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  5. #5
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    Quote Originally Posted by Kev Williams View Post
    Rather than a hammer, do you have a vice? I'd do what you're saying except I'd put the motor, with the socket at the end of the pulley, in a vice- THEN heat the pulley- if you don't have a propane torch, a Bic lighter will work, just some flame so the pulley will expand. After it's good and warm, the vice should push the pulley down the shaft fairly easily, without the shock of a hammer--

    I have found many creative solutions on this site. I was hoping someone would offer one for this situation so that I would not have to dis-assemble the stepper motor from the laser frame. It appears I will have to remove the motor from the laser and use my arbor press to move the pulley down on the stepper motor shaft.

    Thank You,
    Roger

  6. #6
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    if it weren't for the tight space were the motor is maybe a portable vice of some sort. is there anyway to get a small pipe clamp in there to press the pulley down, maybe a wide pair of channel locks can get in there.
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  7. #7
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    Unfortunately the motor is mounted in such a way that it is very difficult to "push/pull" against a surface that will permit the pulley the be "pushed/pulled" in a straight line to avoid placing a lateral load on the shaft and bearings.

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