Induction from spindle

Hi all,

I started seeing inductions that obviously come from spindle (happening only when spindle’s working). It’s a chinese 500W 12V DC spindle.

Spindle’s power cable runs clear off regular wiring.

So, during cutting operation head suddenly decides that current G1 command contains not for example Y61.0 but Y0.0 or whatever other XYZ or number. Also, sometimes navigation to Sdcard menu shows strange symbols that disappear when I navigate out & again in there. Obviously that’s an induction noise influence.

I have nothing grounded except dust collection hose and actually before it was operating OK. Induction started to happen recently.

Anyone having such problems?

How exactly is your spindle supply wired? A single 12V supply feeding both your ramps (or whatever) and also the spindle? Are you able to use a second supply for the spindle?

I had that exact same problem some time ago with the same spindle (Not sure I’ve corrected it, long time not tried). Do you use endstops ? I think endstops cables can transmit the induction spikes to the board.I’d test and twist them now that I think about it. I suppose you can also test and ensure the cables are far from each other if possible.

Jamie, it’s different power supplies for board and spindle.

Thesfreader, from what I know about endstops (yes I have) they only act when you home. During operation they are unfunctional. As to their ability to induce - well, they theoretically can.

Never mind guys. I disconnected laptop and operating only with LCD - everything is good now. Maybe if I reboot the laptop the problem will go… for a while… I decided to disconnect totally to be in full control of this matter.

If it works when the laptop is disconnected then it suggests maybe something through the ground of the USB compared to ground of 12V for steppers. A big loop could be susceptible to induction. I wouldn’t expect the impedance to be high enough to be a problem, but I’m just an amateur in that area so who knows.

Another thing you could try, since it’s a laptop, is disconnect the computer from power and operate on battery. It would cut the ground loop, if that is related to the problem. See if that makes a difference.

No I am fine with LCD. That was my initial plan to operate without laptop eventually since I am going to assemble several routers and will use laptop only for service, leveling and bug fixing.


Problem did not completely go away. Once in a couple hours during the progress it catches an induction and makes a stupid move thus spoiling the work.

Any ideas what and how to ground/earth in order to avoid this?

Je-sus! Did 8 hours work. During 5 hours it made 8 such stupid moves, spoiled all the work. I just wondered how many more mistakes it will do so didn’t stop. Now, after 5 hours (3 hours left) it put straight cut across the board (wasn’t mentioned to do that) and suspended where it was. Finito.

BTW, I have earthed spindle, Rapms, and I removed feeding wires away from endstop wires and any other wires. Nothing helped.

Any ideas?

What else is on that circuit? We’ve had refrigerators and microwaves do the same thing to the machines. I also had a wonky power supply do that for a while.

If you mean what else there is in the house - everything. The machine is in the basement.

Today I earthed steel frame of the router (upgraded from initial MPCNC legs into steel frame), and cases of both power supplies. All of them had 30 volts between earth and they gave little sparkles when touched. Well, I did it and it didn’t save from the glitch.

I remember that when I used initial MPCNC structure and regular wires - there were no such glitches. Then I installed steel frame and used LAN cable for steppers and endstops. That was the only change. Problem started after such upgrade.

Update. I found that metal objects placed in the vicinity of arduino box have 15-30 volts between them and earth. Removing off the box - potential decreases. Then I measured GND of arduino (actually Minus contact of power supply that goes to GND of RAMPS) and it’s 70 volts between earth. Not sure whether I need to earth that contact, is it safe at all?

That’s not right. You have a short somewhere. None of my machine’s frames are grounded, and I don’t think anyone else has them grounded unless they’ve been playing with plasma torches. There’s also quite a few folks, myself included, running the steppers off cat-5/6 cables with no issues.

Not sure what you mean by short. SC is when there is either a fountain of sparkles momentarily or something stops working. In my case all is working but sometimes brains of router glitch.

I have read that spindle makes noise for sure and that placing capacitor in parallel with spindle solves the problem. Placed one and got a SC - now I can waste one more power supply. This is total BS actually because a lot of people are doing that without problems, I just can’t get it why. Capacitor did not SC, it’s way beyond the safe margins for voltage and capacity - instead something SCed in PSU.

Then I followed another advice by wrapping brains in aluminium foil and grounding it. Done, did not work out.

I have no more ideas.

PS. Forgot to mention, in addition to stupid movements, brains sometimes just hang, which is also considered a glitch (not only by me).

Reminds me of a video I saw a while ago:

Are you running long extension cords? Multiple outlets? Also seems related:

It’s hard to really know what to suggest next because I don’t know the details of your wiring configuration. At this point I think induction or EMI through the air is unlikely. Through the wiring or perhaps originating from a cheap power supply seems more likely to me, and it’s probably worth checking the ground of your outlet is truly grounded.

There should be no voltage between dc negative and ground. If there is, your power supply is faulty, or there’s a short in the system somewhere else. Can we see a picture of your wiring between the power supply and the rambo?

I made ground myself. Hammered 1.5 meters if steel into the ground. Checked - 220 volts of potential with phase, should be ok.

Well, wires are long indeed, like 2-3 meters the longest one I guess.

You see, I would blame PSU too but before installation of steel base (see attachment, marked with red text) it was not happening.

So far I had only big frame (red text on the screenshot) earthed.

While each of pipes (green text on screenshot) had potential from 3 to 11 volts and each of them were not connected to anything. Now I have earthed them too. So not every massive/long metal detail in my MPCNC is connected and all is earthed. Plus the box is foiled and earthed. Testing further.

You’re seeing voltage on the pipes? You don’t have high tension electrical cables over you house do you?

It’s quite funny but I know for sure that voltage on metal objects (including MPCNC pipes) in that area comes from induction that is caused by arduino/RAMPS even if I wrap the brains in foil and earth it.


Update. So many words written about such a thing. Solution appeared to be simple and absolutely not obvious. Bugs came from operating the process with accelerated tuning. I started the job and then went to menu “tune” and increased speed to 160%. Using the tuning I was seeking for optimal speed of bit movement. So, when I operated with acceleration I got bugs. When I increased speed of bit in gcode and stopped using acceleration from tune menu - problem disappeared.

However, I must admit that connection to laptop worsened the case - bugs appeared more often when was connected (and being accelerated of course).

One more suggestion. I stopped using acceleration the same time when I earthed MPCNC pipes. So not completely sure what was the healing factor. However, bugs seem to be logical (programmatic nature) and I didn’t earth pipes long time ago when there were no bugs. This all makes be believe that acceleration is the main cause.

This sounds like a problem. True “earth” as in the dirt beneath you is not the same as the ground (usually green) wire in your outlets. Even if the green wire connects eventually to the dirt near your house (it should), you can’t treat them the same.

I dont know how your house is wired, (or if you even have 3-wire plugs) but you should be using the green ground wire in your outlets to ground everything. If you want to also connect that green wire to the dirt, that is fine, but the green wire is critical. That is the gist of the video I linked above.

From what you have described, in my opinion, the ground wiring is the most likely cause of your problem.

In our country we as a rule do not have third wire. It’s just national opportunist approach in everything and everywhere including houses construction. In my case also. So I have to make ground myself and only for MPCNC usage. And my setup shows 220 volts with phase so I consider it more than enough for the purpose.

Then why did I not have this problem when I operated 100% original MPCNC setup without my editions?

Ok this is helpful because my assumptions were very different based on what is most common here. I dont have the answer but I will think about what might help in your situation.