Zero Method using card stock

As I wait for the Unicorn Touch Probe to become available again I’ve found another way to zero the Z axis.

The other day a politician was campaigning and handed me a flyer while I was in the shop. I happened to be near the CNC and measured it and it’s exactly 0.2mm thick. I now lower the bit until it touches the card; pull it out and lower the bit 0.2mm more than zero. The card holds up better than paper too.

At least the politicians visit was worth something :rofl: I’m voting for the other guy too…


A better way is to use a feeler gauge - they’re super cheap and their thickness is printed right on them.

I use a piece of plastic cigarette pack wrap. Old machinists trick. Lower Z while sliding it under the end mill till it gets stuck at the lowest increment/speed. It’s so thin it’s pretty much zero by the time it’s stuck, no rezeroing unless you need space shuttle tolerances.


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Use a block of metal known thickness and a multimeter. Set it to beep when it has continuity or Ohms, clip the metal piece and the bit. Lower until you hear it beep but don’t go to fast to avoid damage.


Once you’re at this point, you have a probe. Wire it to your controller instaed of the meter, and use a G38.2 command.

Yes but i have not done the research to learn the pins on the board to connect.

I bought a Carbide touch probe not too long ago from the robot shop. Works great. I understand they have a new manufacturer and a stable supply chain now.

The new manufacturer is a robot and has been working on the Probes steadily since arrival:

You’re board likely says “probe” on it. that’s the ones.
Edit: And if it doesn’t it will say “reserved”


So say I hooked it up how do i change the thickness of my plate in the back ground? Also how does the program know the diameter of the bit? I have upgraded to 1.1 and V4 as of today. Do I need to switch away from carbide motion? And which one should I use?


If your plate is the same as the carbide probe, you don’t have to do anything. Setting the diameter of the endmill is done when you’re on the probe screen. That won’t work unless your probe is the same dimensions as the carbide one. There are plans on here (and some people sell) passive probes that are the same size.

If you don’t want to do that, you can use your sheet metal for Z only, and then adjust the Z after the probe cycle (by the delta between your probe and carbides probe).

If you don’t want to do that, you can use another sender, like UGS, which lets you set the thickness of your probe.


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