VFD and spindle blocking software from working

I have recently tried to fit a VFD and spindle to my shapeoko 3xl. It runs perfectly until I actually attach it to the machine and then the software carbide motion and GRBL stop working and will no longer connect to the machine . I have used screened cable to the spindle and they are earthed . I was wondering if it is affecting the usb output to the computer . Anyone else had this problem


I would try disconnecting the VFD from the control board, and see if it’s working ok then. If it is, you’re not hooked up to the vfd properly, and are probably shorting the board to ground.

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Thanks for the reply but I am not connected to a board but I am using it independently


I have not had this issue but it does sound like your VFD or spindle is causing an EMI isses disconnecting the machine.

In most cases it’s apparent that the spindle pin 4 is not actually connected or earthed internally. Can you confirm if you did this?

On my builds I solider a bit of copper wire into pin 4. then ensure this wraps around the top of the spindle casing making contact with a few points. Here is a pic of what I mean - note the wire hasn’t been bent yet.


Ok, well then maybe someone else can help, sounds like @Luke has the best ideas. Do know that you can hook the VFD up to the PWM output on the board, which gives you speed control from your GCode.

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I drilled and tapped a hole in the cap next to the plug and landed my ground with a crimp on terminal and screw.

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I think Mr Beaver has the answer so I will give it a try . Number 4 pin is not connected but do you also earth it through the VFD as well.

Thank you for your replies



Yes, you want to ground your spindle to the ground wire in your cable then ground the other end to your power system ground in your shop. Otherwise you have an antenna to spew out EMI to anything that will absorb it like your stepper feedback. Then you start getting disconnects on your system.

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Thank you for your help . It is now working properly. Quiet days ahead.


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