3rd Party VFD & DIY Retrofit

Hi all,

I am after a bit of information on the official Carbide3D VFD 6 pin logic cable, if anyone can help?

Can anyone confirm which pins are connected between the controller and the VFD?

I am currently installing a third party VFD as per all of the good tutorials on the forum (as it is too expensive to purchase, import and transform the official Carbide VFD). All of the tutorials make reference of connecting the “Shapeoko’s GND to VFD ACM (ground)” & “Shapeoko’s PWM to VFD VI (voltage input)” but I was wondering if anything additional could be wired between controller and VFD to mimic the setup of the official Carbide VFD?

Has anyone had the carbide VFD casing open to see whats inside??

If I can mimic the wiring on my third party retrofit then hopefully I caan flash the carbide motion VFD settings to my controller.

Thanks in advance.

Hi @nytram6,

the short answer is that there is nothing beyond the PWM signal / GND / 24V power on the BitRunner connector (that is used by the C3D VFD), nor is there any need for anything else: the PWM signal is the way to control a VFD, regardless of who made it.

VFD can also be controlled via digital interfaces, but that is not very useful in our context.

There is nothing very VFD-specific in the Shapeoko controller settings, beyond adjusting the GRBL max RPM setting (to 24.000, from the default 1000 value for folks who use a trim router), as is mentioned in the thread for setting up a third party spindle/VFD

Bottom line: don’t overthink it :slight_smile:

EDIT: bitrunner pinout is shown here

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Thanks @Julien -

Thought that would have been the case.

Any idea on what the 24v line is doing between the controller and BitRunner/VFD? The requirement for this is not identified in any of the third party installs?

Can the VFD dropdown in the carbide motion settings therefore be utilised on a third party install?

I suspect the 24V may be used to power the internal electronics (of the Bitrunner, or the power LED control part of the C3D VFD), but it’s not required when using a third party VFD that typically only takes the PWM as the external control signal.

I just checked and selecting the “VFD spindle” option in the dropdown list in CM only alters the $30 param (to 24000, from 1000, as I mentioned above), so you can safely use that (but you can also just type in $30=24000 in the MDI, same result)

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I am also looking forward in performing the VFD upgrade to our XXL pro. I purchased the VFD that everyone recommended in the 110V version and also ordered both the air cooled and water cooled spindle. I studied all the posts on programming the VFD so I should be good to go. Does anyone know what the Carbide 3D VFD box has internally? Looks like some type of 110V switching relay.

Got my install complete. VFD drop down from Carbide motion worked fine.

And guess what? I have EMI issues. Only tried cutting aluminium but getting disconnects when there is a heavy cut.

Read the forum, watched many a video on YouTube and provisioned as best as I could - EMI filters, shielded spindle cable, grounded both 4th spindle wire and shielding, ferrite cores on every cable……

Anyone got any further suggestions?

Shielded USB?
Raspberry pi instead of workstation?
Separate power line for VFD?

Would this be limited to carbide motion? Would CNCjs be better?

Any recommendations would be greatly received - invested quite a bit of cash (albeit less than carbides VFD) so want to get this working

@Julien - any recommendations?

Ouch. Not a fun situation. Did you check there everything is actually grounded? (Checking ground with a voltmeter in continuity check mode)
Are you using any dust collection ?
Adding an isolation stage on the PWM signal (and gnd) between the controller and VFD may help.
As to using Cncjs, it won’t make the EMI go away, it won’t “disconnect”, but if it’s the controller who resets it won’t work better. It’s worth trying if using cncjs changes anything, for the sake of testing.

Thanks @Julien

Hoping it’s not going to be a traumatic process identifying the issue.

I will knock up a schematic of what I have wired up and post later.

Haven’t physically tested the ground continuity - but I believe I have been pretty thorough with my install.

Not even started to test with dust extraction yet……

Isolation stage between Vfd and controller? How would I do this? The Vfd to controller cable is shielded but the drain wire isn’t grounded.

I will continue to use carbide motion until I see improvement.

Going to be a bit of trial and error I feel - I will post my schematic and maybe you can propose a list of things to try first? I would really appreciate it.

I’m afraid I’m not very competent when it comes to providing sound advice to keep the EMI gremlins away, when every precaution has already been taken, especially since I was lucky to never have such issues in mine, back when I used a third-party VFD.

You may have seen this thread and others from folks who struggled with EMI on thrid-party VFD setups. What I see being discussed often is adding a standalone EMI filter box either at the VFD power input (mains) or between the VFD and the spindle, and I suspect that the C3D VFD embeds one.

For the PWM itself I was referring to an opto-isolation adapter, I’m sure I have seen a few references on the forum over time but I can’t seem to find one right now

Anyway, let us know how troubleshooting goes, I’m happy to support any way I can, but the help will more likely come from someone in the community who actually struggled with EMI in their third-party VFD setup and finally found a way to address it.

What is the reason you did not ground the drain wire to the VFD?

I have grounded both the 4th spindle wire and the spindle cable shielding

What type of shielded cable did you use?

Did you use shielded wire for the PWM connection from the VFD to the bitrunner connector on the control board? I would also ground the shield for this connection also.

Good point, I didnt ground the drain wire nor the shielded foil.
I will look into this and feedback.
I used a single pair beldan equivalent cable for hte VFD to controller - this is wired to the PWM and GND connectors above the standard bit runner connections on the controller VFD to Controller


The stranded shield wire I found to be really inferior to aircraft quality shielded wire. Aircraft shield is solid core and performs much better. Shielded Wire MIL-C-27500 - White - Per Foot | Aircraft Spruce

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for the VFD to controller or for the VFD to spindle?

How to properly terminate ground shields Garmin G5 Wiring Fundamentals- Shield Termination Methods- Experimental Aircraft - YouTube

Both. Aircraft shield wires comes in all sizes and core counts.

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