Edge Finding without BitZero (on metal)

Hey all!

Is there a generally accepted process for finding the edge of a material without using the BitZero v2?

I have some pieces I’d like to work on where it doesn’t stick up above the jaw high enough to use BitZero, but if I could probe the edges, I could set my work coordinate to the center of the piece.

Curious whats folks have come up with for this, especially when working with a SMW mod vise.

The manual method works. For instance you are using a 1/4" bit. You jog up to a side until you just touch it. Then you would subtract 1/8" from that position to find the edge and set the X and/or Y coordinate. Having the edge of the bit touch you would offset 1/8" because you want the center of the bit to be on the edge.

So jog to touch the edge, jog up to clear the material, jog over half the distance of the bit and set your X/Y zero.

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with CM there isnt a method to probe the edges of stock, as far as I am aware.

Actually, onecan do thus (probe the edge of the stock) if one uses the probe method affordrd by a BitZero.

yes, i believe OP was looking to probe the edge of metal stock without a BitZero.

Do you mean using the BitZero v2 itself? I’m not following.

The v1 BitZero sits aligned on the edge of material and prompts for tool diameter, so will work as expected.

And for Center of stock, I assume one could do:

  • Touch back and zero
  • Touch Front

Set Y to half of the measured value from the front touch off (this would give you exactly middle, including the diameter of the probe).

I was hoping I could somehow do a conductive probing vs paper method, but if I need to do paper, thats fine.

This is what finally drove me away from Carbide Motion and it’s a real shame more probing options aren’t available in CM. I switched to gSender (a derivative of CNCjs, which offers great macro support enabling lots of probing options) and use a probe like:

which is great because you can probe even relatively small holes to indicate a part for second (or later) side machining which works great in conjunction with the SMW vises.

Hopefully, gradually, enough people will keep making similar requests and providing support for 3d probes makes it onto the CM roadmap (or even better, Carbide3D offers their own 3d probe!).


That probe looks excellent!

Do you have a good resource for gSender? I’ve been thinking about trying something like that, but have not had a good resource for it.

Also, do you have configs/macros you could share for the Nomad 3? (Or do you have a Shapeoko?)


I have a Shapeoko Pro so I’m not sure how that changes things for probing. I think that you have a tool length probe for the Nomad so I’ll assume that’s the case. Either way, my macros are all here in case they help:

The probing macros are derived from the @neilferreri ones which would also be a good starting point. Probing X/Y with the 3d probe is pretty straight-forward but the Z probing was actually a bit of challenge because I cannot simply probe the bitsetter button.

In my case, I also have a simple inductive probe (my Carbide3D router is not grounded so I grounded the bed and used that as a probe) and I used that to establish the height of a known surface. My “known surface” is the case of the bitsetter quite close to the button that the tools use for probing the bit length. To get the height of this surface I (essentially) probed the point using a tool loaded with the normal tool changing and probed the same point with the 3d probe to establish what it’s height would have been had it been able to push the button.

If you don’t have a second probe to use to equate the two, you can always do that by hand with a piece of paper.

Once that height is established, I can use one macro to load the probe and another macro to load a tool using the same offsets and therefore use the probe to establish z=0 and the tool will be in kept in sync with that z=0 plane.


I’ll take a look. Thanks so much!

Hey @crpalmer, I’ve had one of those probes in my aliexpress cart for at least a year. I mostly want one to play around with as I find the automation of these machines fascinating, but zeroing by eye is good enough for most things I do.
I was curious…do you know anything about the internal circuit? Is the 5v just to drive LEDs or is there something more interesting going on? Does the probe work with just the signal and ground connections?

Sorry, @neilferreri but I have no idea what the internal circuitry looks like. Based on 3d printed probes I once looked at, I’d imagine the insides are just contact points and no logic which would probably not need the 5V, but again I have no actual knowledge.

A probe like this isn’t really necessary for rough stock setup but it is absolutely necessary when you are doing multi setup (e.g. flipping) jobs where you really can see even a minute difference in the zeroing.

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For this Probe, I wonder if I could wire it up to the BitZero port on my Nomad and use it instead of the BitZero. Hrmmmm :smiley: I need to figure out more about how the BitZero is wired and how this probe works…

Oh, right, I forgot that part.

For the Shapeoko Pro, I have it wired in where you would connect the bit zero. The pinout of the bit zero on the pro is (+V, gnd, signal) which is what is needed for the probe. I forget exactly how the shapeoko pins are ordered, but I figured it out with a multimeter (identify ground then use it to identify +V and that leaves the signal pin).

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with what machine are you using that probe? id love to use one of those with my Nomad 3

Thanks so much for the help!

Here it is in action: Nomad 3 3DTouchProbe Test - YouTube

Now I need to wire it up in a more permanent manner, then configure the probe so the material edges are correct.

Alright, I now have the 3D Probe working for XYZ as well as BitSetter with gSender.

I did the following routine to make sure BitSetter was working as expected:

  1. Homed
  2. Measured 3D Probe with bit setter
  3. Probed XYZ
  4. Changed to an end mill
  5. Moved to Z=1 and put a cig rolling paper under it
  6. Moved to Z=.02, no grab
  7. Moved to Z=0 and it grabbed

I think tomorrow I might swap a few different end mill lengths and re-check Z after using the BitSetter macro.

So far, I am extremely pleased. This is a much nicer workflow when using a modvise, although I’ll probably continue to use the BitZero for non-conductive materials and anything I tape down.

You are measuring the 3d probe with the bit setter?

I have to admit I didn’t actually try that because I assumed it wouldn’t trigger at the right height. The bit setter is a button that has a certain amount of force before it is triggered and the probe has a certain amount of give as it is triggered.

Do you trust the zero probing with your bit zero and do you have it setup in gSender? If so, I’d be curious what happens if you probe Z with the bit zero and then switch tools to the 3d probe and then measure the height at which the probe is triggered on the stock (aka, run a z probe cycle but don’t have it change z=0, just stop when it is triggered).

If they seem to differ, I would also be curious if they differed by a constant amount or if it varied each time you performed the tool change with the probe.