How do I disable Z axis homing when printing from gcode?


Hi everyone,

I currently have a polar 3d 2.5 printer that has a broken Z-stop mosfet and supposedly polar3d has stopped support for it as of september 20th, 2018. I've tried the instructions regarding the bad z mosfet but nothing happens when plugging the usb with the hex file (no lights,etc). In addition, during a firmware update over my local ip I had a power outage which left a lot of functionalities broken (why i now use octopi).

What is the problem?

Aside from the backstory... I'm trying to get around my mishap by printing without a z endstop but whenever i upload gcode through octopi it still homes the z axis when starting.

What did you do already to try and solve it?

I've tried changing some of the gcode to only home to the x and y axis (which are still functioning) with G28 X0 Y0. Then I manually set the Z axis to zero with G92 Z0 when the extruder is comfortably touching a piece of paper at the base plate.

Attached below is the gcode I used. Sorry I'm new to all this :slight_smile:

Additional information about your setup
Octopi version 1.3.9

CFFFP_calibration key.gcode (268.2 KB)


Unless you have told OctoPrint in your GCODE scripts to home on start of a print job or have a plugin installed that does that forever reason, this must be originating from your uploaded files. OctoPrint never just moves your printhead anywhere without either you (manually or through a configured GCODE script), your to-be-printed GCODE file or some third party plugin you installed tells it to do so.


Another exception are Delta printers, they cannot home individual axes so the xyz parameters for the G28 command are ignored ...


That's a problem. Try working on getting a good properly-configured firmware completely flashed to your printer first. It might not be the MOSFET at all.

Open up your part's GCODE file with a file editor and look at the first 30 lines of it and know what they do. Look for a naked G28 without arguments (home all axes) or one specifically which has G28 ... Z0 in it. Edit out the Z part or if it's just G28 Z0 then prepend it with a semicolon to turn it into a comment.