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IndustryArena Forum > CNC Electronics > Spindles / VFD > Can a VFD be used to add variable speed control to this type of motor?
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  1. #1
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    Can a VFD be used to add variable speed control to this type of motor?

    Good morning all,

    I have a Rong Fu 31 mill/drill machine. For a bench top machine it is not too bad and has served be well for the past 15 years or so. I recently upgraded the DRO to the machine and that has made it even better.

    The one that that is really annoying about the machine is the double belt system for variable speed. After a while moving those belts around between the 3 pulleys gets old and I am looking for alternatives.


    The motor is a single phase motor that can be wired for 120VAC or 220VAC, currently wired for 220. Controlling the on-off is a rotary switch like that found on many industrial machines.

    Without replacing the motor, is it possible to control this motor with a VFD? If so, which would be a good choice?

    Chris D.

  2. #2

    Join Date
    Jan 2005
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    10125

    Re: Can a VFD be used to add variable speed control to this type of motor?

    Quote Originally Posted by Chris D View Post
    Good morning all,

    I have a Rong Fu 31 mill/drill machine. For a bench top machine it is not too bad and has served be well for the past 15 years or so. I recently upgraded the DRO to the machine and that has made it even better.

    The one that that is really annoying about the machine is the double belt system for variable speed. After a while moving those belts around between the 3 pulleys gets old and I am looking for alternatives.


    The motor is a single phase motor that can be wired for 120VAC or 220VAC, currently wired for 220. Controlling the on-off is a rotary switch like that found on many industrial machines.

    Without replacing the motor, is it possible to control this motor with a VFD? If so, which would be a good choice?

    Chris D.
    No a single phase motor can not be controlled with a normal VFD Drive, there where some Chinese drives that say they will run single phase motors but have never seen one do it successfully, 3ph motors are quite cheap, and can find a good brand name 3ph motors on Ebay
    Mactec54

  3. #3
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    Re: Can a VFD be used to add variable speed control to this type of motor?

    I was afraid of that.

    Thanks for the info Mactec54.

    Chris D

  4. #4
    Super Moderator Al_The_Man's Avatar
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    Dec 2003
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    23156

    Re: Can a VFD be used to add variable speed control to this type of motor?

    One main issue is that the ones that exist, the motor can drop out of run at either at low RPM or when loaded, hence the popularity of 3ph versions.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  5. #5
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    May 2015
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    Re: Can a VFD be used to add variable speed control to this type of motor?

    People I know swap out the single phase motor for a 3 phase one and add a VFD
    Rod Webster
    www.vehiclemods.net.au

  6. #6
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    Jan 2007
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    382

    Re: Can a VFD be used to add variable speed control to this type of motor?

    You can made it easier to find a 3 phase that will bolt right in without serious mods.
    Determine the Frame Size of your original motor. Measure from centre of shaft to base of the foot. In Australia its in 'mm', ie Frame 80 is 80 mm distance.
    Shaft dia and keyway will probably be the same. Location of terminal box.
    2 pole or 4.
    Should be all you need.

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