Noise filter causing axis creeping - that's weird :/

[ecdez]

I have a small problem with my X axis creeping. Thought it was a pinched wire or a fray or something stupid so disconnected everything and reconnected. Still there. Then I resorted to swapping things between axis to find the culprit, starting with the servos and working my way back. All cables and connections were swapped and the problem was still on the x axis. It wasn't until I went into the power cabinet and worked my way back to the noise filters (the ones on the logic power side) that the creeping changed axis. That seemed strange so I put the the wiring back and it went right back to the X axis. Bypassed the filter and the creeping went away. The next day, the problem was gone. A week goes by and now it's back again; only on the X axis. Bypassed it again just to be sure and the problem went away. Anyone ever hear of this? Maybe a bad unit but it's odd that's it's intermittent.

As a side note, the X doesn't creep until initial movement. If I powered it up and left it, no problem. If I move the Z axis first the X would creep a little but not as bad as it does after moving the X.

I can order another filter but wanted to be sure I wasn't overlooking something else. They're about an inch apart; should that matter? Magnetic interference from something? The Z filter is right there so why affect one and not the other?

Maybe just a bad unit?



Hardinge with an Accuslide - build thread here viewtopic.php?f=60&t=5043&hilit=hardinge





Motors - DMM DST-640 - https://store.dmm-tech.com/products/dst ... ervo-motor
specs - http://www.dmm-tech.com/Files/ACSMTR-G1-1002A18A.pdf

Drivers - DMM DYN4 - https://store.dmm-tech.com/products/dyn ... ervo-drive
manual here - http://www.dmm-tech.com/Files/DYN4MS-ZM7-A10A.pdf - wiring diagram page 22
Wired as shown except the E-stop. I wired that to the Acorn and put a toggle switch in it's place to the drivers.

All driver to motor wires are DMM supplied and the one that goes to the Acorn.

Acorn Board - drives wired to terminals NOT db25




misc electrical supply hardware per DMM manual

breaker - Eaton FAZ-C20-3-NA - https://www.automationdirect.com/adc/sh ... z-c20-3-na

contactor - Fuji Electric - SC-E03G-24VDC - https://www.automationdirect.com/adc/sh ... e03g-24vdc

main noise filter - Schaffner EMC Inc. / FN2030-6-06 - https://www.digikey.com/en/products/det ... sAIQBdAXyA

logic noise filter - Schaffner EMC Inc. / FN2030-1-06 - https://www.digikey.com/en/products/det ... yBsIAugL5A


There's still some wire management to do but here's where it is now.

Control cabinet

Power cabinet

REPORT

report_0CB2B7D683E2-1113203964_2020-12-29_08-10-09.zip

(268.63 KiB) Downloaded 113 times

VIDEO - I move the Z axis 1" via the MDI and you can see the X axis motor jog just a tiny bit.

https://youtu.be/73VwYOKaqlY

[martyscncgarage]

We can't see what you see. Could you kindly take the time to review this post and follow it?
viewtopic.php?f=60&t=1043

Pictures of the control cabinet, description of the machine and always post a fresh report when asking for help.

The more we see/understand the better suggestions we can make.

Marty

[ecdez]

Marty you are right!! My apologies, I didn't even consider it could be anything else since I had traced it to the noise filter but that may just be a coincidence. Original post has been modified with hopefully all the necessary information.

Fired it up this morning and no problems until about 30 minutes in to playing with it. The problem is on both axis now (maybe all along just didn't notice). The video in post above shows very slight movement but it was much worse yesterday. I wonder if it gets worse the longer it runs? I'll have to leave it on for a bit today and see.

[martyscncgarage]

I will be honest. I am a bit concerned with your wiring.
First it is good practice to use VFD cable when wiring from the VFD to the spindle motor. I ground the shield AT the motor and AT the VFD.
Automationdirect.com is a good source for the cable: https://tinyurl.com/ydzyz3el
I do not know what HP your motor is. 16 gauge will likely work with up to a 2hp motor.

Also, it "looks" like you used shielded cable to the VFD. Did you ground a shield at one end?
All shields taken to one common ground point?

When the axis CREEP, I assume the DRO's on Acorn are not changing?
As a test, unplug the analog signal to the VFD from Acorn and see if that stops the creep.

Really should clean up the wiring in the cabinet. Neaten it up...

Attached is a picture of one I just finished. Not perfect but its working well with no issues.
Good wiring practices are important in CNC controls.

Good luck!
Marty

[martyscncgarage]

Also, you are running version 4.18, we are at 4.50 you really need to get upgraded to the latest software.

[ecdez]

If I knew what I was doing I wouldn't be here

I still consider the wiring temporary as things may still need to be re-arranged. Didn't want to cut anything too short until I was sure everything worked where it was.

The wiring to the spindle from the VFD is what was in the cabinet already. Just some heavy gauge cable. I will plan to replace. It is a 2hp motor.

The cable to the VFD is shielded. I forgot to ground that. I'll add it to the list.

When the axis CREEP, I assume the DRO's on Acorn are not changing?
As a test, unplug the analog signal to the VFD from Acorn and see if that stops the creep.

That is correct. I will try that and see what happens.

I updated everything when I got it but apparently I missed one

I was also thinking about removing the noise filters from the power cabinet and putting them right next to the drivers in the control cabinet and see if that changes anything. Might be picking up some noise in the 4' of cable between the cabinets?


I know electronics can be funny but can the VFD wiring really be causing one axis to creep because the other is moving?

I'll try each of these one at a time and hopefully can weed out the problem.

Thanks for your help thus far.

[martyscncgarage]

My hunch is you have an EMI problem (Electro Magnetic Interference) Inducing noise on the cable to the DYN4's
VFD's can cause this issue.
First try and unplug the analog wires to the VFD to see if this stops the creep.
Next power down the VFD and see if the creep stops.

Some have had better success connecting their DYN4's to the DB25.
I have not had such problems nor had to resort to that.

You should work on that wiring.
Did you set up all this on the bench and test motors before putting the components in the cabinet?
Sometimes trying to reuse the existing cabinet is not the best way to go.
The cabinet I used was about $80 from Zoro.com and they only charge $5 to ship.

Just my observations....
Marty

[martyscncgarage]

It would have been better for you to put this thread in with your original build thread. Hard to keep track of who's working on what....

[ecdez]

I will try those things first.

I bought a DB25 breakout board just in case but was hoping not to use it.

I did do the bench test. Come to think of it, the VFD was the last thing I hooked up recently. Hmmm. Might be on to something there. There's plenty of room under the machine once I pull out all the hydraulic stuff. I could even relocate the VFD if necessary.

Do you have a link to the cabinet you bought?

And thank you for your observations. They are much appreciated.



I thought a separate thread would help future searchers find answers to problems but I do see your point. I can't imagine how much you're trying to keep track of.

[martyscncgarage]

https://www.zoro.com/wiegmann-nema-1-18 ... ifications
NOTE: This is an 18"x18"x6" deep cabinet. You would need a DEEPER cabinet because of your DYN4 drives.
I also have the local metal supplier cut me a piece of .1" thick aluminum plate for a back panel. I wire the back panel and test before installing in the cabinet and final wire.

This is also a NEMA 1 cabinet. I add a closed cell foam gasket. This has a cover and not a door. I mount a 4" fan to the bottom of the cover and a screened vent to the top of the cover and call it good. We went this route because it was cost effective for the customer multiple machines.

I have also purchased several of these and used them with good success:
https://www.zoro.com/wiegmann-nema-1-30 ... /G1357151/
Again, I gasket them and add fan and screened vent.

Marty