Cura: set z-offset

  • I'm having a Prusa i3 derivative printer with a capacitive sensor for the z-axis. It switches a tiny bit before the nozzle hits the print bed and hence needs a z-offset to be configured.

    In Slic3r I have configured the z-offset to -0.1 on the General page of the Printer Settings, but currently I'm evaluating Cura and can't find such a setting. Slic3r seems to apply this setting directly to the generated z-values in the g-code, so it does not use a short version at the beginning of the g-code. My current (except of the auto-bed-leveling part default) g-code:

    G28 ;Home
    G29 ; auto-bed-leveling
    G1 Z15.0 F6000 ;Move the platform down 15mm
    G92 E0
    G1 F200 E3
    G92 E0

    Is there a way to configure Cura, e.g. using the Start Gcode options, to apply the z-offset?

  • You can trick the printer into applying an offset using the G92 command:

    G0 Z0

    G92 Z0.1

    First, we move the nozzle to Z=0. Next, through the G92 command, we tell the printer to, from now on, treat the current position as Z=0.1. This effectively applies an offset of -0.1 to the Z-axis, since if we now executed G0 Z0 again, the nozzle would move down 0.1mm.

    Note that this needs to be done after homing and leveling to be effective.

    Of course, you don't necessarily need to move the nozzle to Z=0 for this to work. You could also just insert G92 Z15.1 after G0 Z15 to get the same effect.

    Should I add the line `G92 Z15.1` after the `G1 Z15.0 F6000` line (you write about G0 while G1 is there)?

    Yes. `G0` and `G1` are the same thing. Formally, `G0` denotes a rapid move and `G1` a coordinated move, but Marlin doesn't make this distinction. It's just "move".

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Content dated before 7/24/2021 11:53 AM