Fixing Electromagnetic Interference and Grounding a CNC
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- čas přidán 29. 06. 2019
- I determined that electrical interference is causing communication issues with the stepper motor encoders on my CNC. In this video I show you how I fixed this problem.
This is what I needed! I thought I was going crazy!
Great video man, thank you. Helping me build my plasma table right the first time
Nice! Hope it goes well. I have always wanted to make one of those.
Good work. The only remark is that you wanna start with pockets, and finish with contouring.
Sage advice! Still trying to get Fusion 360's CAM software down, in the chaos that is my brain I definitely mixed up my operations while trying to figure out how to export the program. Thanks for watching and the feedback.
Thank you very much. I finally got to test my completed CNC machine today, and my spindle is throwing all kinds of EMF making the machine not work properly. I like the fixes that you did and will try the same. I think shielding and grounding the spindle's power cable along with the spindle itself was probably what fixed it. ...but I like the idea of grounding the machine too.
Glad to help and good luck!
Dear Becky Schwantes
My name is Hristo, I am from Plovdiv, Bulgaria. I have read your comment to this video clip and
I have decided to write you (I have no another way to make this).
I have tried to make my first hobby cnc machine, but my experience of electronics is very small.
I have a question about Grounding. I have to note before, that our building is old, and there are
only 2 conductors, and we have not separate conductor for Grounding unfortunately. This system
is TN-C and TN-C-S. In this case, we have to use “neutral” for this kind of Grounding.
The main elements of electronic are: Arduino Uno; 3 steppers-NEMA 24- 3,1 N.m; 3 stepper-drivers-
SH-750- 5A, PSU-s - one 36V DC for steppers, and other - 12V DC for fans, (5V for Arduino from
computer‘s USB).
I will not use a VFD for motor-spindle. I have intention to use routing motor-spindle, and I will
connect it directly to 230 V- AC, and will be no connection to controller.
I will Grounding 2 PSU by “neutral” in “star” point (in TN-C-S system), but I am afraid to connect
in this “star” point stepper drivers (GND) and Arduino (GND). I think, that it will be too risky.
To install separate ground rod is not easy task.
What do you think about this situation ?
Best regards
PS: Excuse me for my too bad English language.
To be honest I am not sure what the best approach is in Bulgaria, I am not familiar with your electrical codes and standards. I bet a local electrician could probably provide more accurate information than me on what is allowed in your country. I do hope you figure out a good solution.
@@orangelabengineering2923 Thank you very much. I have looked for different opinion everywhere.
i have a plasma home made cnc table i built........everytime i go to cut out a part it moves around erratically and my x and y axis move completely off course and it messes up my work........i dont have my table grounded but how exactly can i ground it? theres a steel bean next to my table which goes into the ground, i was thinking of grounding into that but do i also have to utilize my ground pin built into my torodial power supply inside my electronics control box? will that help?
The behavior you are describing is more than likely caused from insufficient shielding of your power and control cables. You should have a ground rod sunk at least 8 ft deep. Make a ground bar and mount it in the panel. Land all your shield wires and equipment grounds there. A piece of brass cleaned up nicely with an assortment of tapped holes will be your ground bar.
I just replaced all my steppermotor- and endstop wires with shielded cables on my 6040 cnc.
I have a 24v powersupply witch has the only ground-connection on the cnc at the 220v side (mains).
Can i connect all the shielded cables of the steppermotors and endstops to the ground of the 220v connection?
i have a torodial power supply for my plasma cutter.....do you think if i connect my steel frame to the ground terminal on my power supply it will help with the noise ? im having issues with noise and my motors are moving very erratically.
Let me start off by saying I have zero experience with CNC plasma tables and I am not an electronics engineer, so take everything I say with a grain of salt. That being said let me ask a few questions. Do you have shielded signal wires to your stepper motors? Also is the cable from your plasma cutter to the torch cutting head shielded? If the answer to both of these are no, then I think those would be a good place to start. I think grounding your CNC frame would be good, but most likely wouldn't be the "fix all" solution for your problem.
As far as how to ground your CNC frame, I would think routing a ground wire from your frame to your stepper motor power supply ground terminal could work. Your power supply should come with some good literature on where to connect the ground wire. Hope this helps!
You need to measure the resistance before you do anything. Is the power supply grounded now?
No wonder why I get static shock when touching MPG hand wheel and frame gantry because not grounding properly. So I just need to connect / bonding the wire to the frame flow thru the control panel box earth is it.. thanks
Well you need to sink a ground rod and then there should be a ground bar in the panel. Connect them with a strap. Then find a clean spot to take a ground from the panel to the gantry. Don’t jump around. You run a cable out and land it and if you need another you start in the panel and run out again.
Very good Info thank you
How do you connect the ground from the cnc to the ground coming for the wall socket? Thanks in advance
In my design I made that bond inside the control panel using a terminal strip.
You don’t!!!!!! You drive a ground rod and run a strap from the rod to your ground bar in the panel. Your residential ground is bonded with nuetral.
What kind of shielded cable did you use. Are they flexible?
To be honest I am not sure, it has been so long since I installed the cable. All of the copper conductors are stranded and pretty flexible. I think the cable I used was made for security cameras, but I can't remember for sure.
How did you connect the three wires to the house earth ground? Via the control box?
Hey Mert Capkin. Yes you are 100% correct. I routed all of the ground wires to a terminal strip inside the control panel and terminated the "grounding conductor" (green wire) from my house on there as well.
@@orangelabengineering2923 so they are connected to the ground of the main power input of the control box? or is it a separate plug?
They are all connected to the ground of the main power input for the control box.
@@orangelabengineering2923 alright, thanks! :)
Hi, can I prevent interference if I put a ferrite core on the cables?
@Dave Tennes Thank you for your answer. You shared very useful information. My problem is solved for now. I connected a cable from the CNC case and the spindle motor to the grounding line, there is no problem now.
An electrical engineer told me aluminium foil shielding on wiring does nothing for emf problems. Remember it is an electrical magnetic problem. Aluminium will not block or shield against a magnetic field. I have had to separate stepper motor wiring and controller wiring with steal sheet metal partitions and ground the frame to get rid of hesitation problems.
I have to respectively disagree with the electrical engineer on this one. Based on my experience and research shielded cables are not 100% effective but do block most of the EMF from outside sources. The aluminum foil shield protects the signal conductors inside the shield from outside EMF fields as long as the shield is attached to ground. That is why all shielded cables have an inner aluminum foil lining. Maybe what the EE meant was that the outer aluminum shield does not protect the conductors inside of it from internal EMF interference, which I believe is true. Thanks for watching the video.
Ask your EE how eddy currents interact with aluminum (or any other nonferrous metal).
Please reply me back. Since i am facing the same issue. Are you using Sheilded wires for limit switches too?
Yikes, this is not a proper grounding application. You need a ground rod installed for the equipment ground. You don’t use your residential ground which has been bonded to nuetral. You always use a braided shield for any cable that will be flexing the foil shield will break. You absolutely never run high voltage in the same track as control voltage. If you insist on having them in proximity of each other you run them perpendicular never parallel. Also you are simply testing for continuity with your meter you are not comparing the potential. You did some nice work .... sink a ground rod and install it right. You don’t want to be fighting noise issues a couple years from now when that foil cracks and your shield is broken. Your grounding system should be capable of serving as a protection circuit and a location to disperse noise equally well! You seem pretty sharp. Look up Tpc cable they specialize in super flexing cables with any shielding option you might desire! Make a nice power cable and use that braided sleeve as a ground strap!
Thanks for watching the video Becky! While I agree an isolated ground rod would be ideal for reducing noise it is just not practical where I have my CNC set up. I also 100% agree with not running Line voltage next to low voltage in parallel...... but I am a sucker for clean install. Since I haven't seen any noise issues since making these changes I figured the SO cable's metal braided sleeve is blocking the noise well enough to allow the power cable to stay in the drag chain. I was not aware the foil shields have a tendency to break over time, thank you for the insight. I will need to look into the TPC cable. Thanks for the constructive feedback!
@@orangelabengineering2923 I’m a sucker for organized cable runs also! Check out the TPC. We have a certain type of machine that has multiple conduits running in a track that flexes with the axis . It’s all under a waycover and the conduit eventually always breaks and a wire will get damaged. We stopped running single conductors in a conduit and used one of their multi conductor flex cables NOT in conduit and it hasn’t even nicked the jacket!
steppers dont have encoders
You are 100% correct. I misspoke there.