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

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1

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)

2

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.

3

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

4

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.