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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > HF 44991 X2 Mill wired so pot/switch is "backward"
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  1. #1

    HF 44991 X2 Mill wired so pot/switch is "backward"

    Hi there, I am not an experienced machinist or electrician; my apologies if this is obvious stuff.

    I bought a used HG 44911 a while ago, and have had problem with it from the start. The pot was damaged, so I ordered a replacement from the Littlest Machine Shop.

    Unfortunately, the little labels on some of the wires fell off while I was waiting for the replacement, so I had to figure out the wiring from whatever I could find online. While I think everything is right (certainly the P1-P3 wires look correct), no matter what I try I can't get the potentiometer part of the speed control knob to work. The spindle does not move at all when anywhere in range of on positions, and runs at full speed when the knob is clicked to the off position.

    I'm at a bit of a loss as to how to pursue fixing this. My biggest concern is that the wiring is wrong in some way that is dangerous.

  2. #2
    Join Date
    Nov 2012

    Re: HF 44991 X2 Mill wired so pot/switch is "backward"

    The best way would be to trace the wires from the pot to the controller/VFD using an ohmmeter.

    It is also safe to try all 3 wires randomly IF you keep the potentiometer around the middle position and don't turn it all the way CW or CCW.
    Connect the potentiometer (keeping it centered), turn the spindle on. If the spindle runs at half speed, then the wiper wire is in the right place. Then you just may have to swap the two track wires.

  3. #3
    Thanks, I'll do that. The condition I received the unit in does not guarantee that there are issues only with the speed control though. I suspect the problem maybe elsewhere, and I'm not particularly well equipped to identify it.

    I had been hoping that the specific symptom I'd mentioned, where the spindle only turns when the pot is in the off position, would point to a common issue.

  4. #4
    Join Date
    Nov 2005

    Re: HF 44991 X2 Mill wired so pot/switch is "backward"

    Does the fault light ever come on?

    If the X2 is like the X3 and I think it is be careful with the wires to the pot. They are at mains level with respect to ground. If those wires touch anything that is connected to ground it will blow a trace on the board.

  5. #5

    Re: HF 44991 X2 Mill wired so pot/switch is "backward"

    The fault light doesn't come on. I tested the voltage for those wires to the pot, and yes they are mains level. Fixing this up was mostly just for fun; I may just move on to a new machine. Thanks for the feedback.

  6. #6
    Gold Member
    Join Date
    Nov 2009

    Re: HF 44991 X2 Mill wired so pot/switch is "backward"

    Get a new machine because of a problem with a potentiometer?
    It is wired incorrectly.
    Do the test mentioned above.

    Sent from my iPhone using Tapatalk Pro
    A lazy man does it twice.

  7. #7
    Join Date
    Jan 2018

    Re: HF 44991 X2 Mill wired so pot/switch is "backward"

  8. #8
    Join Date
    Apr 2018

    Re: HF 44991 X2 Mill wired so pot/switch is "backward"

    If the pot is backwards (i.e. pot rotated max clockwise translates in min spindle RPM and vice versa) then just swap P1 and P3 wires

    Sent from my SM-A520F using Tapatalk

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