Z Probe for 3018 Pro




Introduction: Z Probe for 3018 Pro


I wanted to mill PCBs on mei 3018 Pro but it had no Z Probe Pin.
Because I couldn't find any Instructions how to do it, i made in myself.


  • Solder Iron
  • Wire Stripper
  • Wire Cutter
  • Thin wire (or better an enamelled copper wire)

Step 1: Z Probe Pin

The CNC runs on GRBL 1.1 so I found the right Pin where the Z Probe should be connectet to.
My CNC Controller Board had an ATMega328 so the Z Probe should be connected on Pin 28 (SDA)

Step 2: Pull Up

To prevent the Z-Probe from triggering in an undefined way, a pull up resistor is needed.

I used an 4,7kOhm Resistor. The Resistor is Solderd between Pin 28 and VCC of the ATMega. (see Picture)

Step 3: Connect

The Z Probe can be connected between Pin28 and GND. There is no need to change the Firmware.

Only on GRBLControl I needed to add a command for the Z-Probe: "G38.2 Z-1 F1; G92 Z0"

The last fracture of the command sets the Z Axis of the Machine on zero. There you can change the thickness of your Probe.

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    Question 1 year ago

    Hi, have similar board however slightly different. There are X-lmt, Y-lmt and Z-X-lmt sockets like yours however mine seems populated (tracks go DIRECTLY to the atmel 328p chip - see photo #2) as follows:
    X-lmt +/- to pin PB1
    Y-lmt +/- to pin PB2
    Z-lmt +/- to pin PB4

    I think you have to check if these are populated (maybe on the other side of the board because of some vias - with or without resistor) at your version and use these pins instead of hacking a wire to a pin. I am still not sure how to use it because on the socket there is a ground pin and connecting a wire between gnd and the pin doesn't seem to do anything. I am also not sure these pins are used in the firmware because I have an older firmware 0.9. Where did you find the firmware update 1.1? I prefer the Arduino code to see how it is configurated and to be able to change something.



    Reply 1 year ago

    I've read the parameters of the old Firmware of mei board. I think the command $$, just wrote it in candle software and then flashed the grbl 1.1 from github on it and just the parameters with the g commands.
    I've desolderd the Atmega328 and there were no tracks visible. But I havent measured it with the multimeter.


    2 years ago

    Working perfectly, thx!


    Question 2 years ago on Introduction

    Hello, how can i connect the limit switch. I can't find any wiring diagrams for this motherboard. Thanks in advance.