How to connect an electronic touch probe?

Since, as far as I can tell, there are no working edge-finders or touch-probes for the Nomad, and I need one with high precision, I’d like to add this (note there’s a language switcher at the top right of the page) and I’m wondering how to go about connecting it.

There’s a manual here but I haven’t been able to find any documentation of the Nomad’s electronics so I’m not sure how exactly to wire it. I’ve seen this post which gives a good starting point but I’m not sure how to adjust for the 12V/24V power requirement of the probe I’d like to use, or its different “NPN” and “PNP” connection diagrams.

Anyone have any pointers?

Hooking up digitiser probes might not be the best - looks can be deceptive and they are usually too big for a Nomad style machine. Using one without fixed reference points will also lead to loosing your Z position and some are only designed to be used in fixed tool holders.

You can also use a manual edge finder or end mill to do edge finding. It’s pretty easy to get within 0.1mm with a 3.17mm end mill, edge finder or ground rod. I’d bet @WillAdams has more on this.

I would email and we the support team can run through the above with you.

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Hooking up digitiser probes might not be the best - looks can be deceptive and they are usually too big for a Nomad style machine.

I’ve noticed, I was looking at this one in particular because it seems it should fit. The dimensions are specified in the manual. It should stick out ~70mm from the collet with the short probe attached, so it’s a little shorter than my Mitutoyo dial test indicator, which fits (quite snugly however). Worst case I’ll make something to stick it firmly to the Z-carriage and measure the offset.

Using one without fixed reference points will also lead to loosing your Z position

I’m fine with adding a fixed reference point to the machine, e.g. a precise square cube somewhere near the tool probe.

You can also use a manual edge finder

I’m not able to source one that can tolerate the Nomad’s spindle RPM range.

or end mill to do edge finding

What do you mean by this? Moving towards the material until you see a small cut? Or hooking up an electrode and trying to close a circuit?

Regardless, I feel I’m going to end up doing a lot of multi-setup jobs so I’d really like something that can be accurately automated or at the very least done very rapidly.

There are some links on this sort of thing at:

The Nomad controller is the same as the Shapeoko’s (as of this writing) just with a spindle control board on it which is substantively the same as the opensource Stepoko board:

and if you let us know your board revision number we can send you some annotated diagrams which may help.

The edge finder which was bundled with the Nomad was a commercial one (the two I was sent were made by Fisher in Hawthorne, Ca.) which was labeled as “MAXIMUM 1500 RPM”) — which is probably part of why it is no longer available from Carbide 3D.

It will be interesting to see if this aspect of the machine is revisited for the new model (which is probably something which a current owner doesn’t want to hear).

Pop a small end mill or ground rod in the collet. Move this toward stock (with spindle off) 0.1mm towards the stock at a time, when you see no space/light or feel friction between the stock and rod set that axis on zero. Repeat for three axis.

On CAM set stock with half the end mill diameter on X/Y.

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Thanks, both!

The Nomad controller is the same as the Shapeoko’s (as of this writing) just with a spindle control board on it which is substantively the same as the opensource Stepoko board:

The main difference is that the Nomad already has the touch probe connected to the probe part of the board. Is it safe to connect two probes to the same connector somehow? Should a different connector be used instead?

or feel friction between the stock and rod set

To be clear, you mean by trying to rotate the rod/endmill by hand and seeing if it spins freely?

C3D uses a “Probe Adapter PCB” for a Probe+BitSetter combo (pg. 7). As there is no electrical components that I can see on the board, I imagine it is just wiring the two Normally Open (NO) probes in series, vs if they were Normally Closed (NC) in parallel, I’ve seen this type of wiring for example via multiple hard limit switches.

While I personally like to run my probes and switches NC, you can switch the Probe I linked on the other thread to operate in NO mode to simplify wiring (after had suggested their converter at first).


The nomad has its tool length sensor plugged into the probe port next to the limit switches BUT on a 2.4d/e board you can attach another probe to the “reserved” header and it works totally fine.

So satisfying :slightly_smiling_face:


How did you wire your probe to the reserved header? Do you know what the pinout is?

And any clue if the voltage of the probe matters and where on the board to draw power from?

So I’ve taken a multimeter to the machine and I think I understand what’s going one now.

The stock tool-length probe is a Normally Closed probe. When I put a voltmeter across its two pins, I see a 5V reading, which vanishes when I press in the probe (the circuit is flipped open). One of the pins (the one on the right) is GND, the other I assume is the switch.

The probe I intend to use is also a normally closed probe.

On the v2.4e board that I have, the pins for the reserved header appear to be, from top to bottom:

  1. GND
  2. 5V
  3. Switch

So I think I need to install my new probe on pins 1 and 3, same as the other probe.

The question now is whether the reserved header is wired in series (good, multiple probes can work) or parallel (bad, only one can be connected and useful at a time). I’ll check tomorrow by depressing the tool length probe with the multimeter across the reserved pins.

@DanStory I think you got your terminology mixed up the same way I did. I heard “closed”, which in non-electrical contexts (e.g. a door) means “separating two things”, and thought “closed” meant the circuit wasn’t connected. In electrical contexts, “closed” means that the circuit forms an unbroken (“closed”) loop, i.e. works and electricity flows.

If you hooked up a bunch of Normally Open sensors in series, as long as one of them is open, no electricity would flow through the circuit, so it’d only function if all the probes were activated at once.

You want series for Normally Closed probes, so that if any one probe activates, the circuit breaks and the switch is “activated”. You want parallel for Normally Open probes, so that if any switch is closed, energy flows and the switch is “activated”.

And the mystery is solved, the switch pins on the Z-axis probe and reserved header are wired in series, so two NC switches can be connected to them simultaneously.

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Aaand the plot thickens. I think I’m an idiot and you can disregard pretty much all of my conclusions so far.

I tried to install my probe and discovered that the pins are not wired in series. If they were, the circuit would always be open, as the reserved header is usually unpopulated.

I’m not yet sure how things are supposed to work. While I was poking around with the multimeter I shorted something that shouldn’t have been shorted and now the board seems to be fried.

And I did what I should have done in the first place: probed the Z-probe switch directly. It’s not NC after all, it’s NO. I apparently don’t know how to use a multimeter.

@Moded1952 So, less self-flagellation and ask some questions! :smiley:

My question right now is whether it’s worth keeping the Carbide Motion controller board at all.

I can either:

  • Pay a currently unknown price to ship another black box from the US, that the manufacturer doesn’t want me screwing with.
  • Pay ~half the price for something locally available, open source and well-documented.

TinyG for example seems to be very closely related to the Carbide Motion board. It uses the same drivers laid out in a very similar way. It’s open-source, very well documented and more widely available.

I’m not sure if I want to go that far right now though. I know that at least if I buy the Carbide Motion board replacement, I can make it mostly work without too much effort. If I buy another controller, I’ll have to configure everything myself.

Its really up to how much your time is worth imo.

TinyG is pretty cool because it’s a little more advanced in the motion department. I have a Bantam Tools mill that runs it and man is it smooth. Its more like programming a 3d printer.

Hard to go wrong with the C3D controller because its plug and play unless the shipping is really gonna be crazy high. Sucks to hear you blew one, in my experience they have been exceptionally rugged. I’ve done quite a bit of tig welding (with high frequency starts) on the machine and they have been solid, no issues.

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Can you be more specific about the board being “fried”. What’s not working?

Also, grbl is open source as well, and there are open source controllers.

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@neilferreri I’ve elaborated elsewhere and I’m in touch with support about it. The short of it is when I turn on the power, the LEDs light up then fade to nothing. The machine never connects via USB.

True about Grbl. I’m aware of that but Carbide Motion isn’t open source. That’s the problem, I have to use my extremely poor electronics skills to figure out how the board works.

The board is much like a Stepoko:

and if you write in to us at with your board revision information from the silk screen we can send you some annotated EDIT: board diagrams which may help.

One board which seems to work well is the Gradus M1 Pro from Panucatt:

and if Carbide Motion doesn’t suit how you wish to work with the machine, there are other options:


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