Current state of EMI on the shapeoko

I’ve had my S03 for many years and have had EMI issues with it basically forever (controller locks up if the load gets moderate). I found work arounds (different USB cable, ferrite chokes, splitting motors onto different electrical circuits, power filters, grounded vacuum hoses, USB optocoupler sent to me by C3D, etc etc) but all of them eventually fail. I’m in the market for an upgraded machine and would like to stick with carbide 3d, but I can’t do the EMI dance anymore. I’ve ruined way too much work.
Does anyone know anything about the shapeoko pro? I know it has new electronics and I thought I heard something about additional EMI shielding on it but it would be cool to more specifics about the controller.


Sounds like a strange issue and I’m sorry to hear of your problems. I’ve got a stock SO3 xxl with the Dewalt 611 from 2016 and maybe I’ve been lucky but I’ve been free from emi issues. I wonder what is different about your set up or environment? I’m going to ask some questions and I hope that’s okay.

Are any other devices on the same circuit experiencing issues? Are there any other devices plugged in that may be creating a heavy load? (Vacuum, Fridge, air compressor, etc). Are there any power cords running next to the usb cable to grbl board?

That’s all I can think of but maybe others can help. A picture of your setup may also be of use. I’m not sure if the pro is different but a normal SO3 should not have these issues and maybe we can save you having to upgrade!

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From the perspective of the great number of us that have had issues: Yes, you’ve been lucky.
I couldn’t get anything to work with my original 2015, white controller. Been ok with the 2.3, using separate circuits, and rerouting of router cable. Navy have had more severe issues.

That’s the problem with the “user friendly” USB connection in place of something more robust like Ethernet. I can see why Carbide went that way, but it would be much nicer to have an Ethernet option as well.

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Agreed 100%.

I had a lot of issues with the CM boards, Carbide 3D were very supportive in troubleshooting but ultimately I ended up changing to a CNCdrive UC300 over ethernet, running under UCCNC.

With this setup I can start and stop Shop Vacs, Mitre Saw, Circular Saw, dust collection and palm routers on the same power board as my shapeoko and control PC while running a job and have no issues with disconnects


It would be interesting, on a machine that shows the problem often enough to get good test data, to try a Raspberry Pi running CNCjs mounted next to the Shapeoko controller with a super short USB cable. The Pi can use an isolated PSU with no ground reference.

Then use WiFi to talk to CNCjs on the Pi.

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always ok to get more info. To be clear, C3D has been amazing and super helpful trying to work through the EMI issues which is why I really want to stick with them for my next machine. The customer service is outstanding but I believe there are some fundamental issues with at least a batch of our machines and I’m hoping the new controller fixes those. But the short summary is that when under a moderate load (say 4mm engagement, 3mm DOC into MDF with the makita set to 3 and various feedrates) the controller seems to lock up and requires a restart. The only thing that works is taking very light passes and hoping for the best. Over the years we’ve chased down just about every option you can think of from all the ones I listed to replacing darn near every supporting system, cable, I even bought a new dust collector (and stopped using dust collection entirely for awhile).

I don’t mean this post as C3d bashing at all, seriously I will pay for the new controller the moment it is available if it will fit the S3 and has better EMI rejection, I’m just looking to see if anyone knows more about it and what makes it different.

that’s actually what I’m doing currently. Just tonight I switched to a 6 inch cable, isobar dedicated power conditioner, grounded the bejesus out of everything in sight and running CNCJS on the Pi with an optoisolator on the USB port. CNCJS just sees the controller stop responding when loaded up.

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That’s a pretty extreme case, did you try it without the USB isolator?

Which board rev are you running?

How old is the PSU brick? (they can get low voltage or noisy with age)

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Did you try a Sinewave UPS?

yup, I’ve got the optical one sent to me by c3d. it’s fine really, it’s been something we’ve been working on for years without no real resolve. Mostly just trying to see if anyone knows anything about the new controller.

no but we’ve tried all sorts of other power filtering and isolation. sometimes it works, sometimes it doesn’t. Mostly just trying to track down if anyone knows anything about the new controller.

If your problem is a dirty power source, I believe a true Sinewave UPS should fix it, for around $220. I don’t know anything about electric so, just a suggestion.

Appreciate the suggestion . Power seems to be fine, it’s filtered, one distinct circuits and I’ve moved houses with the shapeoko a few times with the same issue. For those of us that have the issue, it seems to be the controller picking up interference somewhere during load that causes it to reset. I probably should just get out the oscope and probe the holy hell out of everything while I’m cutting at some point, but I’d honestly rather throw money instead of time at it if C3D has a better option.

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All of my EMI issues stemmed from two things:

  1. Turning on my DeWalt router and having a disconnect due to (I guess EMI or voltage surge or voltage drop - not sure) magic. I inadvertently solved this by buying the SuperPID controller and used it from the get-go. I found out my SO3 was susceptible to the router power-on EMI issue when I tried it out and removed the SuperPID controller from the system. At the time, I had a pre-order SO3 controller board without the large filter caps.

  2. Static from whatever I was cutting traveling through the vacuum hose. I first encountered the static disconnect during the winter, when the relative humidity of my shed was very low (when you warm up cold air, the relative humidity - RH - drops, and with low RH you get higher static buildup). I would get “random” disconnects when cutting wood.

One time, I was cutting some StarBoard (UHMW plastic) and I was moving the vacuum hose around trying to find a good way to anchor it over my SO3. When I touched the hose, I felt the static buildup and got a little tingle. I didn’t think too much about it at the time, and I then touched the frame of my SO3 for no real reason, just to rest my hand there to watch the machine cut, and it immediately lost connection.

Weird. That sucks. I was able to recover (PITA, but successful) and kept cutting the UHMW plastic. I could feel the static on the hose if I put my arm up next to the hose as it was sucking up the plastic shavings. It was pretty strong actually. That gave me the idea. I waited until the ctting was done for that project, then touched the hose and then touched the frame of my SO3. Disconnect.

Okay, so for me, it is a static issue.

I started by buying the USB opto-isolator. That did not work.

I tried using ferrite beads. That did not work.

I tried using an UPS - APC Smart UPS 1500. That did not work.

I bought some “anti nuisance hose” that is conductive. That did not work until I grounded it properly, and after that, I never had an issue with static disconnects again - unless I forgot to ground it before starting.

I sold that machine and I now have an XXL and a VFD/spindle. I use 4" flex hose with a steel wire in it and ground the wire, and the last time I had a static disconnect was when I forgot to ground the wire. I should ground the wire where it connects to the rest of the system, but I put a “temporary” ground wire and alligator clip right at the point where the hose hooks to my Suckit, so I have to hook/unhook each time I put the Suckit on. I put that “temporary” wire on 18 months or so ago. I’ll get it done right eventually.

Now, I did inadvertently test this not too long ago. I was cutting some wood, and the ground wire came undone. It must have run for ~5 minutes before I noticed, and when I went to hook the ground wire alligator clip back on the ground wire of the vacuum hose, it disconnected.

So, for me, my “random” disconnects were all related to static in the vacuum hose. Hopefully, this may assist you in identifying the nature of your disconnects.


ahh yes, I had a very similar experience back when I was on a plastic vac hose. I ended up buying the rockler grounded vac hose and I also got a dust collection grounding kit that I additionally ran through the vac line. It did help out a fair bit for awhile and I thought I had found my answer. I’m starting to wonder if I just have too much cumulative damage on this poor dude as I didn’t find that solution until fairly late in the game.

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For anyone interested, I ordered a 6-pack cnc controller last night ( and an rpi-cnc ( to see if I can get my SO3 back on its feet while I wait to hear more about the new controller. One of those hopefully will do the trick.


I ran a ground cable from the Dewalt 611 body to a grounded outlet in my table base and my edit problems went away. I still run my USB through a hub, which Ed helped in the beginning whilst sorting it all out.

My table rests on a base that I use for rigidity and electrical (router and vac control, safety kill switch) and I disconnected the ground when replacing a relay. I hadn’t reconnected it yet and the controller froze twice in two days before I realized I had forgotten it.

Might help if you haven’t grounded it yet. Brushed motors are noisy I think.

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I understand your frustration, I had the same issue with EMI when I first got my Shapeoko and I tried all the suggestions listed above with no results. Then somebody mentioned using metal screening (like from a screen door). I wrapped it around the top head of the Dewalt router, the control box on the Shapeoko, the USB cable going to my laptop, and because my laptop resides in a cabinet with a separate monitor, I lightly wrapped the screen around the laptop. It looks a little ridiculous but I went from having EMI issues every other cut to zero issues and it’s been running like that for around 2 years. It’s worth a try as it’s not very expensive.


You built a Faraday cage for it, nice.

You don’t have to be an enemy of the state to find a use for one :wink: