Spindle EMI causing servo drift

[replicapro]

This machine has been running fine for 10 years. I moved the machine the other day and used it no problem. Came in the morning and as soon as the spindle was turned on, all 3 servos started to move. I tested it with out the PC on and just the spindle is causing interference and moving the servos a lot.
I tried foil wrapping the servo cables as well as the spindle cable but no real improvement.

I use the Camtronics servo box with g340 geckos.
The mill is a first gen X3

What I dont understand is how this can all of the sudden start pushing out electronic interference after 10 years of working fine.

So what should I do? Should I ground the foil I wrapped on the cables? If so, where do I connect the ground wire to?
I've been trying to fix this problem all day, and I am stuck.

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[replicapro]

After grounding all the signal cables I still had servo drift from the spindle motor. So I foil wrapped every single cable and nothing stopped the problem.
I decided to go through the process of elimination by removing one cable at a time. It was when I got to the 5 Volt USB cable that the problem went away. The USB cable is foil wrapped and grounded, but still does not prevent servo drift. What could be causing this?

[replicapro]

Is anyone knowledgeable about this problem?

[A_Camera]

After grounding all the signal cables I still had servo drift from the spindle motor. So I foil wrapped every single cable and nothing stopped the problem.
I decided to go through the process of elimination by removing one cable at a time. It was when I got to the 5 Volt USB cable that the problem went away. The USB cable is foil wrapped and grounded, but still does not prevent servo drift. What could be causing this?

Have you tried to replace the cable completely? Foil wrapping cables is not as good as shielded cables. Also, try to replace the 5V supply. You could try with any cell phone supply with USB charger, if it is a quality type. I use several Samsung chargers from previous phone models for different 5V needs and they are excellent. Use proper USB cable, they have good shields.

[replicapro]

this morning I solved the problem by relocating the servo drive box and PC to the opposite side of the room that the spindle motor is in. Just as I was about to run a program, the Y axis motor spun free and faulted. I swapped out the g340 for my unused A axis G340. (basically brand new) and it also had the same problem and spun free.
I checked the other g340s and at first I thought they had also failed, but after a phone call to Marcus at Gecko and a few more tests, the X and Z are fine. I used the X axis to test the servos on the Y and also a unused servo I had for the future A axis. The X axis G340 function fine on my Y and A servos. So right now I have 2 G340's that are malfunctioning.
I did on advice from Gecko turn the gain all the way up on all drives, while fighting the signal noise problem. When that problem was solved, I turned all the trim pots on the gain back to about 50%. I noticed the trim pot on the gain for the Y axis has sunk into the case of the G340, but it still works as I was rotating it while the servo was spinning free.

Gecko advised me to start from scratch, and go through initial set up again. So I am trying to figure out the PDF manual on how to do that with out a multimeter. Still not certain what is wrong with the g340's. It is weird that the A axis G340 would also suffer the same problem as it has never even been used.

[Eldon_Joh]

is the spindle drive grounded, with shielded motor leads grounded on both ends?

while folks can argue about grounding both sides of a vfd cable... you don't want a failed motor winding in your spindle electrifying your machine with high frequency pwm at +/- 170vdc at 4+ khz. and the machine has to be grounded anyways.

[dharmic]

To basics: the moving of it suggests either that there's something about its new home that's causing the issue (unlikely) or that you've busted or made some connection in the process of moving it.

It's unlikely there'll be enough energy in the EMI generated along the spindle cable to actually move the steppers. Much more likely that it's inducing enough voltage in the control lines running into the stepper drivers to get them to move the steppers.

So if I was foil wrapping anything it'd be the cables between the BOB and stepper drivers. First, though, check your earths for spindle motor, VFD, frame, stepper drivers, stepper PSU and BOB/controller. If the BOB or stepper drivers are floating earth this would be a fairly likely result.

[Eldon_Joh]

It's unlikely there'll be enough energy in the EMI generated along the spindle cable to actually move the steppers. Much more likely that it's inducing enough voltage in the control lines running into the stepper drivers to get them to move the steppers.

he has servos.. and needs to make sure the encoders cables are shielded as well.

[dharmic]

:facepalm: apologies, must have gotten this thread confused with something else. Of course you're right.