Jcut Router, ghost in the machine


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Thread: Jcut Router, ghost in the machine

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    Default Jcut Router, ghost in the machine

    Hello I have a JCut Router that is 5 years old. I am a very part time 'machinist' who has some time to dive in with a little more energy this fall.

    My machine, when I initially turn it on
    • works fine in the z and x
    • the y2 side moves along the rail (in either + or - directions) without corresponding y1 movement (so the y1 gets 'dragged' with a big clunk)
    • sometimes there are what sound and feel like heavy stepper movements but the gantry does not actual progress anywhere

    When I leave it on and try to work out what might be going on (dust? short? bad connection?) the machine can sometimes start 'firing' seeming pulse movements? This is the 'ghost in the machine' part. There are heavy and loud pulses and sometimes they can come in rapid succession, the machine trembling from them, but there is not actual movement of the gantry or spindle. When this happens I can actually still move the machine in the x and z and sometimes the y 'normally' but it is clearly not good.

    I will try to upload a video of this. I have looked in the controller box and cleaned it out.

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    Default Re: Jcut Router, ghost in the machine

    video of asymetrical Y movement




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    Default Re: Jcut Router, ghost in the machine

    Looks like the motor on the left is not going. Drop/disengage the Y driver assemblies from the rack and pinion and see if the motors move. Work back from there. You could trace the wiring from the Y motors and swap them at the driver modules to check the motor/drivers.

    Cheers,

    HarryE.
    ===



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    Default Re: Jcut Router, ghost in the machine

    Its time to change out controller.



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    Default Re: Jcut Router, ghost in the machine

    Harry, Thanks. I will check that out. The thing is that, sometimes, when I leave the machine on, the motors DO work but there is a relatively violent pulsing that I can pinpoint cause it seems like its coming from everywhere. Then, sometimes, when I leave the machine on long enough the pulsing stops, the motors all work fine and I can run tool paths. I can figure out what leads to this point of functionality. In any case, thanks for the tip and I will check it out. For now the machine is working and I am just leaving it ON 24/7 so as not to have to deal with what I know will happen if I turn it off and back on again.



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    Default Re: Jcut Router, ghost in the machine

    Quote Originally Posted by asuratman View Post
    Its time to change out controller.
    Is there any way to more specifically diagnose it as a controller issue before I buy one and swap it out?



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    Default Re: Jcut Router, ghost in the machine

    By disengaging the motors from the rack/pinion you remove the mechanical contact so you might be more able to identify unusual noise sources. The video shows the left side is "stuck". With the motors free to turn with no load it should be easy to see if after power on both Y motors turn as they should, you can also check the bearings/ways for Y are not binding.

    If after power on, the LH motor does not turn normally, swapping the motor plugs (after power off) at the driver ends should move the problem to the other side (be mindful of motor direction). If LH motor is still not moving it's the motor. Otherwise it's driver.

    Alternately, you know the RH motor wants to move. Disconnect LH motor and plug RH motor into LH driver. If that doesn't move it's the driver module. Otherwise its the LH motor so repeat this with only the LH motor and chances are it won't move using either driver.

    Since the LH motor seems locked its less likely to be a power supply issue to the LH motor but if the above doesn't isolate the issue then look there. (Don't have a wiring diagram to refer to for your machine).

    This assumes, the controllers step/dir/pulse signal for Y is common for both motor drivers for the 2 Y motors.

    Do NOT disconnect/connect motor driver plugs with power on!!!

    Put plugs back to normal.

    (That flexing of the gantry can't be good in the "broken" state :-))



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    Default Re: Jcut Router, ghost in the machine

    Quote Originally Posted by he1957 View Post
    By disengaging the motors from the rack/pinion you remove the mechanical contact so you might be more able to identify unusual noise sources. The video shows the left side is "stuck". With the motors free to turn with no load it should be easy to see if after power on both Y motors turn as they should, you can also check the bearings/ways for Y are not binding.

    If after power on, the LH motor does not turn normally, swapping the motor plugs (after power off) at the driver ends should move the problem to the other side (be mindful of motor direction). If LH motor is still not moving it's the motor. Otherwise it's driver.

    Alternately, you know the RH motor wants to move. Disconnect LH motor and plug RH motor into LH driver. If that doesn't move it's the driver module. Otherwise its the LH motor so repeat this with only the LH motor and chances are it won't move using either driver.

    Since the LH motor seems locked its less likely to be a power supply issue to the LH motor but if the above doesn't isolate the issue then look there. (Don't have a wiring diagram to refer to for your machine).

    This assumes, the controllers step/dir/pulse signal for Y is common for both motor drivers for the 2 Y motors.

    Do NOT disconnect/connect motor driver plugs with power on!!!

    Put plugs back to normal.

    (That flexing of the gantry can't be good in the "broken" state :-))
    Thanks so much, I will try this out and let you know what happens. Right now I am just leaving the machine in the "on" state to avoid dealing with this issue until I have more time.



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    Quote Originally Posted by danielcoyle View Post
    Is there any way to more specifically diagnose it as a controller issue before I buy one and swap it out?
    What you have is one motor connection not working and one (or more?) Connection getting extra pulses.

    The good news is that is isn't too hard to figure out inside a cabinet. if possible, check or change the wiring to the stepper drives. make sure all ground wires are working as they should. Make sure any spindle or power wires are well clear of the stepper control wires....the magnetic field they put out can cause false steps.

    I would bet the controller is fine and it's the wiring that's messed up. Good luck!



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    Quote Originally Posted by gfacer View Post
    What you have is one motor connection not working and one (or more?) Connection getting extra pulses.

    The good news is that is isn't too hard to figure out inside a cabinet. if possible, check or change the wiring to the stepper drives. make sure all ground wires are working as they should. Make sure any spindle or power wires are well clear of the stepper control wires....the magnetic field they put out can cause false steps.

    I would bet the controller is fine and it's the wiring that's messed up. Good luck!
    Just realized that you, with a day control, would also have potential issues with the wire from the dsp pendant to the cabinet....is that something can be swapped out?



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    Default Re: Jcut Router, ghost in the machine

    Quote Originally Posted by gfacer View Post
    What you have is one motor connection not working and one (or more?) Connection getting extra pulses.

    The good news is that is isn't too hard to figure out inside a cabinet. if possible, check or change the wiring to the stepper drives. make sure all ground wires are working as they should. Make sure any spindle or power wires are well clear of the stepper control wires....the magnetic field they put out can cause false steps.

    I would bet the controller is fine and it's the wiring that's messed up. Good luck!
    Thanks gfacer and everyone else. Like I said the machine has been working fine as I have just left it on and, magically, the problem went away after it "warmed up?". In any case, yesterday I pulled the usb out of the controller to put a new file on it. When I put the USB back in the pulsing (not the asymetrical movement) started up again. I could run in X,Y and Z and even run a short run on a test file but the machine pulsed irregularly the whole time. So, I turned it off, back on and then got, predictably, the asymmetrical y motor behavior again along with some pulsing in the background and then, after waiting a while, it started working normally again. Just an update, its pretty cold in the shop and I am not inclined to dig into the wiring until it warms up but I REALLY appreciate the insight and direction for when that moment comes. I will update on what happens from doing the wiring work and thanks for the tips about the magnetic field interference.



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Jcut Router, ghost in the machine

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