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IndustryArena Forum > CNC Electronics > Spindles / VFD > weird problem: random movements when spindle is running
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  1. #1

    weird problem: random movements when spindle is running

    Hi there!
    A few days ago I bought my first CNC machine! (:
    It is a big F3000 from cnc1 from the year 2005. The deal was so good that I couldn't say no haha
    Today I set everything up and tested the machine to the best of my abilities. Then something really weird and unexpected happened... When I left the spindle running und did not touch anything, the machine made random short jerks on a random axis. Most of the time it was in the x direction but I also saw y and z. The time between the jerks appeared to be random and 20 seconds to around to mins apart.
    I tried disabling the jog button and even disconnected the keyboard to rule a malfunction there out. I checked the control box and couldn't see any loose wires, obviously that doesn't rule out that the problem is there.
    Furthermore it didn't happen when the spindle wasn't running so I guess it must be some kind of interference within the control box?
    Another problem could be that there are electricity fluctuations in my garage, the neon lights sometimes turn off randomly...
    Any other clues or suggestions for troubleshooting?
    Thanks a lot in advance for your help!
    Greetings from vienna!

    Edit: it's running mach3

  2. #2
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    Re: weird problem: random movements when spindle is running

    You definitely have a problem with high frequency noise from your spindle.
    There are a couple ways to cure them.
    Shielded cable from spindle to VFD, shield connected only on VFD side.
    Reactor in front of VFD.
    Machine and computer should be properly grounded.
    Make no mistake between my personality and my attitude.
    My personality is who I am. My attitude depends on who you are.

  3. #3
    Quote Originally Posted by ZASto View Post
    You definitely have a problem with high frequency noise from your spindle.
    There are a couple ways to cure them.
    Shielded cable from spindle to VFD, shield connected only on VFD side.
    Reactor in front of VFD.
    Machine and computer should be properly grounded.

    Thank you! After a sleepless night of research I came to the same conclusion haha
    The first thing I will do is separate the cable of the spindle from all the others, because right now it is running closely and parallel to all the others.
    If that fixes it I will probably try to use shielded cable and install it like it was before, because I really like that there are no cables dangling around.
    If it doesn't fix it I'll try the reactor (:
    I'll let you know of any progress!

  4. #4
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    Re: weird problem: random movements when spindle is running

    Quote Originally Posted by felixaustria View Post
    Thank you! After a sleepless night of research I came to the same conclusion haha
    The first thing I will do is separate the cable of the spindle from all the others, because right now it is running closely and parallel to all the others.
    If that fixes it I will probably try to use shielded cable and install it like it was before, because I really like that there are no cables dangling around.
    If it doesn't fix it I'll try the reactor (:
    I'll let you know of any progress!
    The Shielded Cable must have the Shield Grounded at both ends not how ZASto has said if you need to know how to Ground the Shield correctly I can add some snips

    A Reactor can help but a power filter mounted close to the VFD Drive input power terminal's can be more beneficial for EMI control

    Are you using Single Phase or 3 Phase supply
    Mactec54

  5. #5
    Quote Originally Posted by mactec54 View Post
    The Shielded Cable must have the Shield Grounded at both ends not how ZASto has said if you need to know how to Ground the Shield correctly I can add some snips

    A Reactor can help but a power filter mounted close to the VFD Drive input power terminal's can be more beneficial for EMI control

    Are you using Single Phase or 3 Phase supply

    Hi!
    So first of all I'm using single phase 230V (:
    The last time I looked into the control box there was a usb cable curled up in loops and bound together in there... At the time it didn't come up to me that this could be a problem but after thinking about it that could be it right? I was never good at electronics but a coil in an electromagnetic field isn't good when it comes to transmitting signals haha
    So that will be the first thing I will change because it's also an easy fix!
    Btw thanks for all the suggestions, in what order would you try the changes, obviously having in mind how easy/difficult they are?
    Greetings!

  6. #6
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    Re: weird problem: random movements when spindle is running

    Quote Originally Posted by felixaustria View Post
    Hi!
    So first of all I'm using single phase 230V (:
    The last time I looked into the control box there was a usb cable curled up in loops and bound together in there... At the time it didn't come up to me that this could be a problem but after thinking about it that could be it right? I was never good at electronics but a coil in an electromagnetic field isn't good when it comes to transmitting signals haha
    So that will be the first thing I will change because it's also an easy fix!
    Btw thanks for all the suggestions, in what order would you try the changes, obviously having in mind how easy/difficult they are?
    Greetings!
    USB cable could be a problem, so if you replace it make sure, it is shielded and has at least ( 1 ) ferrite Choke on it ( 2 ) is better, USB cables in general can be a problem the ideal cable is like the snip with what ever ends you need for your connections

    Spindle Cable and Power Filter, Power Filter being first as you have not said what the cable from the VFD Drive to the Spindle is and how it is connected this needs to be a 4 wire Cable with a Shield Ideal IGUS sells one of the best Shielded cables and you can buy it by the foot

    This Power Filter has to mount as close as you can to the VFD Drive input power connection ( TDK Lambda RSEN-2030L this has a 30Amp Rating ) this 2 needs to be sized for your system, these are inexpensive compared to a Line Reactor

    Ground connections must be connected correctly on power supplies spindle motor VFD Drive Etc.

    Use a Ground Bus where you connect all Grounds to one point ( Star Point Ground ) Remove paint from any Ground mounting points

    The IGUS Cable is CF6-15-04 this will handle up to 18Amps so depending on your Spindle size the cable Amp rating needs to suit
    Mactec54

  7. #7

    Re: weird problem: random movements when spindle is running

    ok right now i have the control box of the machine open in front of me and the usb cable ist just the power input of the breakout board... the computer is connected to the board via db-25 cable. i guess for this cable the same things apply. after a quick search i could not find one with ferrite chokes preinstalled but i think you can buy those to clip them on cables right? im not sure if my cable is properly shielded but i think i can check if the housings of the connectors are connected with a multimeter.

    i am pretty sure that the cable from the vfd drive to the spindle is not shielded, at least there is no visible shield connected in the vfd. i will buy a shielded cable and install it.

    should i order a 30A rated power filter in any case, also to protect my machine or leave it if the other two things solve my problem?

    i want to keep changes in the wiring to a minimum so i will probably leave the ground connections as they are or is that also a bad idea?

    there is a 2.2kw spindle on my machine and i will look for a proper cable!

    thank you so much for your help!


    edit: i could actually use some help on deciding what cable to buy because igus has a LOT!
    spindle data:
    2.2kw
    230V
    6.8A

  8. #8

    Re: weird problem: random movements when spindle is running

    Update:
    The spindle cable is shielded but it's not properly connected to the ground of the spindle and not at all to the ground of the vfd! I'll fix it tomorrow, hopefully that's my solution
    Thanks again for all the help!

  9. #9
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    Re: weird problem: random movements when spindle is running

    Quote Originally Posted by felixaustria View Post
    Update:
    The spindle cable is shielded but it's not properly connected to the ground of the spindle and not at all to the ground of the vfd! I'll fix it tomorrow, hopefully that's my solution
    Thanks again for all the help!
    The USB cable would not be a problem then although not ideal the Breakout Board should have it's own 5v power supply not from the computer as it most likely is not opto isolated

    The Grounds don't have to connect to The VFD drive they all need to be connected to one point though Star Point Ground this can be a Bus or a Ground Stud a Bus is the best when you have a lot of connections to make some snip to give you how you have to do this to be successful
    Mactec54

  10. #10
    Quote Originally Posted by mactec54 View Post
    The USB cable would not be a problem then although not ideal the Breakout Board should have it's own 5v power supply not from the computer as it most likely is not opto isolated

    The Grounds don't have to connect to The VFD drive they all need to be connected to one point though Star Point Ground this can be a Bus or a Ground Stud a Bus is the best when you have a lot of connections to make some snip to give you how you have to do this to be successful
    Hi!
    Yesterday I wired the shield of the spindle cable correctly but it didn't change anything. Then I separated the spindle cable from all the others and ran it separately to the spindle and the random movements were still there.

    Maybe it's worth mentioning that I don't think it's just one step auf the motor but a lot more! The machine moves a few centimeters when it happens.
    Furthermore I looked at the diagnostics screen in mach3 and sometimes the control lights of the output signals list light up shortly, sometimes the lights light up und the machine moves, sometimes the machine moves and the control lights don't show anything. Could that be a clue on what's going on? Maybe a problem in my computer, breakout board or axis controls?

    Now that I looked properly at all the cables of the machine I would say that the whole job of cabling was done very poorly, it does not look professional at all!

    When it comes to grounding of the machine, did I understand it correctly that I basically attach an earth cable to the spindle, all the steppers and the control box and connect it all to one point and then to a grounding rod?

    Thanks again for all the help I really appreciate it!

  11. #11
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    Re: weird problem: random movements when spindle is running

    Quote Originally Posted by felixaustria View Post
    Hi!
    Yesterday I wired the shield of the spindle cable correctly but it didn't change anything. Then I separated the spindle cable from all the others and ran it separately to the spindle and the random movements were still there.

    Maybe it's worth mentioning that I don't think it's just one step auf the motor but a lot more! The machine moves a few centimeters when it happens.
    Furthermore I looked at the diagnostics screen in mach3 and sometimes the control lights of the output signals list light up shortly, sometimes the lights light up und the machine moves, sometimes the machine moves and the control lights don't show anything. Could that be a clue on what's going on? Maybe a problem in my computer, breakout board or axis controls?

    Now that I looked properly at all the cables of the machine I would say that the whole job of cabling was done very poorly, it does not look professional at all!

    When it comes to grounding of the machine, did I understand it correctly that I basically attach an earth cable to the spindle, all the steppers and the control box and connect it all to one point and then to a grounding rod?

    Thanks again for all the help I really appreciate it!
    Does it do this with the VFD Drive spindle turned off ???

    Need to see some photos of the different connections

    The spindle is Grounded with the 4th pin in the plug you have to check that the 4th pin in the spindle plug is connected to Ground, you do this by checking the 4th pin to the spindle body with a meter continuity check, if this is not connected then it has to be corrected under the top cap of the spindle

    No you can't use a Ground rod, you use your mains power service Ground which runs though out your electrical system
    Mactec54

  12. #12
    Quote Originally Posted by mactec54 View Post
    Does it do this with the VFD Drive spindle turned off ???

    Need to see some photos of the different connections

    The spindle is Grounded with the 4th pin in the plug you have to check that the 4th pin in the spindle plug is connected to Ground, you do this by checking the 4th pin to the spindle body with a meter continuity check, if this is not connected then it has to be corrected under the top cap of the spindle

    No you can't use a Ground rod, you use your mains power service Ground which runs though out your electrical system
    No it doesn't do it when the spindle is not running!

    So the ground wasn't connected to the connector plug that plugs into the spindle. I opened up the spindle housing and the fourth plug where the ground is supposed to go is not connected to the housing... So I just connected the shield directly to the ground because I suspected that the spindle has a connection to the earth via the machine itself somewhere else. When I'm there again I will also connect the housing to the earth.

    What photos would be helpful? Vfd connections, spindle connections and maybe control box?

    Thanks again!

  13. #13
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    Re: weird problem: random movements when spindle is running

    Quote Originally Posted by felixaustria View Post
    No it doesn't do it when the spindle is not running!

    So the ground wasn't connected to the connector plug that plugs into the spindle. I opened up the spindle housing and the fourth plug where the ground is supposed to go is not connected to the housing... So I just connected the shield directly to the ground because I suspected that the spindle has a connection to the earth via the machine itself somewhere else. When I'm there again I will also connect the housing to the earth.

    What photos would be helpful? Vfd connections, spindle connections and maybe control box?

    Thanks again!
    The ground is connected under the cap like photo or similar, no the shield should not be connected to the Ground it needs to be clamped by the connector as yes any photos of all the VFD Drive connections and control box

    You can use a longer screw that holds the plug in place for the Ground connection or drill and tap a new hole for the connection
    Mactec54

  14. #14
    Quote Originally Posted by mactec54 View Post
    The ground is connected under the cap like photo or similar, no the shield should not be connected to the Ground it needs to be clamped by the connector as yes any photos of all the VFD Drive connections and control box

    You can use a longer screw that holds the plug in place for the Ground connection or drill and tap a new hole for the connection

    PROBLEM SOLVED!
    I just had to connect to spindle to ground as well... Thank you so much for your help I don't know how long it would have taken me to figure this out by myself... Really really appreciate it!

  15. #15
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    Re: weird problem: random movements when spindle is running

    Quote Originally Posted by felixaustria View Post
    The deal was so good that I couldn't say no haha
    ...Now we know why it was a good deal. Good to hear you found the problem.

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