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IndustryArena Forum > MetalWorking Machines > Tormach Personal CNC Mill > Installed spindle power quick change, now my spindle is dead, need motor resistance
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  1. #1
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    Unhappy Installed spindle power quick change, now my spindle is dead, need motor resistance

    Hi,

    I did what I should not have and did 3 upgrades (spindle motor quick disconnect to prep for rapid turn, the smart cool and the power meter) at the the same time on my series 3, very shortly (say about 45 seconds over two cycles) after powering up the spindle at 250RPMs with no load it died. - lesson learned one upgrade at a time.

    Smart cool works, every thing works, except spindle.
    It spun for about 15 second the night I installed it and it was in the right direction sounded right so I called it and went to bed happy, next morning I wanted to verify the speed of the spindle and while getting the optical revolution counter ready the spindle just stopped, tried e-stop, reset, power cycle nothing brought it back

    1. Spindle door switch is making good contact past the trip point as that can prevent the VFD from coming on.
    2. Spindle lockout key works, have used it to clear the codes and it was not moved when this started.
    3. Double checked all my wiring at motor electrical box and owed out every cable form VFD to motor and all looks good, no shorts between lines nor opens on lines. No poor connections with stringers.
    4. C2 contractor (controls power to the VFD motor drive):
      1. Only engages if I disconnect the 3 motor lines from the VFD (400, 401, 402) but as expected gives an error code, it looks like tr r5 - suspect this is indicating open load, did not trace this as i expect an error.
      2. C2 contractor does not engage if I leave the 3 motor lines connected to the VFD , have finally gotten it to show me an error code and its 01.AC - which the manual describes as "VFD output instantaneous over current" infers a short to the motor or at the motor, not sure why its now showing a code all of a sudden, but while in the early debug I got nothing (hum, maybe early debug was misleading due to issues with 105/105A (spindle door open as the contact on the shorting bricks at the bottom of the cabinet are weak at best, wires come out easily and are a pain to put back in) anyway I got a code and its telling me ohm things out.

    5. few more observations:
      1. Getting same result with path pilot as with manual controls which bypass the parallel printer cable/ribbon cable - so its not these cables. (also both reverse and forward do the same and I would suspect they are on different wires of these cables)
      2. FU01 and FU02 fuses are good
      3. By the way the motor is wired as a delta not a Y, did not change this.
      4. Also tried sticking in the PCNC 1100 programming key (when mill was fully off) in the VFD, powering it back on and testing spindle, but that did not help.


    Here is the key help I would really appreciate - I measured around 3.2 - 3.3 ohms between any of the 3 lines at the VFD (wires 400, 401,402) after disconnecting them from the VFD but leaving them connected at the motor, does this sound right? Can anyone measure to confirm this is expected, I find it hard to believe that I killed the motor, but would really like to know if this matches readings for other PCNC 1100 spindles.

    Will look for a VFD self test in the morning.

    Any debug suggestions welcomed

    Thanks

    PS: Tormach support (the reason I went with PCNC 1100) called back and was great to talk with, gave many ideas and insight based on no error codes, but with a full time week day job, I only get to debug at times when Tormach support is closed, so hoping community can help me get this system back up - thanks
    Learning to use a Tormach Series 3

  2. #2

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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    igrau

    I's this mod a disconnect between the motor from the VFD or just disconnects the starter/contactor for the VFD input power, so it turns off the power to VFD

    Turning ON/OFF a VFD within a short time frame is not a good idea
    Mactec54

  3. #3
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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    @maxtec54

    Its the motor from VFD, for easy swap of motors to say the rapid turn motor.
    Learning to use a Tormach Series 3

  4. #4

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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    Quote Originally Posted by igrau View Post
    @maxtec54

    Its the motor from VFD, for easy swap of motors to say the rapid turn motor.
    That a very bad idea, to have a switch between a VFD and motor, it is very easy to damage both motor or VFD by having a switch in this position
    Mactec54

  5. #5
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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    I measured the resistance on my series 2 machine. There was 4.3 to 4.6 ohms between each of the lines.

  6. #6
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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    3.2 ohms is about what I would expect.

    Check from each phase to ground and see if there is a short, with the motor plugged into the disconnect, measured from the three wires at the VFD (with them removed from the VFD terminals).

    Grounding is far more likely to be the issue.

    Does the C2 contactor not even try to cycle shut when you manually power the spindle from the front pane; keyswitch (can you here it "clunk")? Your machine control board shouldn't know that the VFD is seeing a shorted condition until the VFD powers on. This is a very strange scenario.

    I would take four wires (phases + ground) and run them straight from the vfd to the junction box on the motor, and see if that works. That would isolate the problem as the section of wiring you messed with.
    Tim
    Tormach 1100-3, Grizzly G0709 lathe, Clausing 8520 mill, SolidWorks, HSMWorks.

  7. #7
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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    Quote Originally Posted by wvines View Post
    I measured the resistance on my series 2 machine. There was 4.3 to 4.6 ohms between each of the lines.
    Was that with the wires disconnected from the VFD?
    Tim
    Tormach 1100-3, Grizzly G0709 lathe, Clausing 8520 mill, SolidWorks, HSMWorks.

  8. #8
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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    Quote Originally Posted by tmarks11 View Post
    Was that with the wires disconnected from the VFD?
    Yes. But it measures the same whether it's connected or not.

  9. #9
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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    @maxtec54

    Hum, its a Tormach kit to do this not my own design. It allows one to physically unplug one motor and plug in another - power must be off to do the change also requires changing the VFD programming stick. Curious, what makes this a bad idea?
    Learning to use a Tormach Series 3

  10. #10
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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    @wvines - Thank you soooo much for taking the time to do this on your machines with VFD disconnected - THANKS
    Learning to use a Tormach Series 3

  11. #11
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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    @tmarks11 - many many thanks for the comments

    You are right the c2 contractor does engage both with key + closed door + manual start button or with key + closed door + path pilot. Yes like you said its the power to the VFD and I see the contractor sink in to make contact in both cases and in both the VFD quickly goes form 00 to 01.AC. My poor wording was related to when I got no codes as the unit was not powering up likely form poor 105 contact.

    Measured ohms to ground on the 3 lines to the motor at the VFD end (disconnected from VFD) and get ~167-173k ohms to GND, is this also in line with your expectation. I noted it takes my ohm meter a while to settle down as if there is some capacitance but I don't see any other than parasitics of wires running next to each other.

    Yup will try the jumper wire idea next but suspecting its not that as the measurements seem about right to me on the VFD end to the motor - please tell me if you thing I am wrong.

    Thanks again, very much appreciate your time and ideas

    Regard
    Learning to use a Tormach Series 3

  12. #12

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    Re: Installed spindle power quick change, now my spindle is dead, need motor resistan

    Quote Originally Posted by igrau View Post
    @maxtec54

    Hum, its a Tormach kit to do this not my own design. It allows one to physically unplug one motor and plug in another - power must be off to do the change also requires changing the VFD programming stick. Curious, what makes this a bad idea?
    If it where to be switched at the wrong time you will damage the VFD, there are special switches that can do this, but not at the small machine Hobby level

    They should never have done this most VFD Drive Manufacturers do not recommend to do this as per snip attached
    Mactec54

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