View Full Version : CNC3040 Z Probe problem.

22-03-2018, 12:30 AM

I wonder if anyone can help with a z probe issue I have.

I have a Chinese CNC3040 cnc machine, with a arduino to db25 adapter - basically converting grbl to mach3.

I have the A5 and GND pins wired for a z probe in GRBL.

I am using BCNC software and when i short the 2 z probe wires - I get confirmation that the zero point has been reached.

When I carry out a z probe routine on the actual cnc (gnd to chassis and z probe to milling bit) - the probe stops short of the zero point and I have to run the routine 2 or 3 times before it actually get to the correct zero point.

I have checked all the wiring on my 3040 - as they are known for bad GND`s. I have also checked the continuity from the chassis to the milling bit to make sure its open circuit.

Does anyone have any ideas how to solve this problem?

Do I need a resistor or capacitor to smooth the z probe line?

Many thanks in advance.


23-03-2018, 12:09 AM
Hi Iain have a look at my blog. Copy and paste the code and forget to put the height of your code in. All is explained in the text

23-03-2018, 12:12 AM
Sorry here’s the link

23-03-2018, 12:14 AM
Hi Kev,

Many thanks for the info. I literally just found the solution to my problem :)

I put a 100nf cap between the probe pin and ground and now it all works great :)

Itching to do some milling, but got work at 6am :(