Oxplow Nozzle Z Offset Search - Generic Version

This gcode will help find the correct z offset for a 3D printer's nozzle. It is a back and forth square (hence “oxplow”) that begins at -0.1 mm below the current nozzle offset and raises it each row until it ends at +0.1 mm above the current nozzle offset.

I find this is easier than my previous test squares method as well as being faster, covering a wider range of nozzle offsets, and having a finer resolution.

The gcode was generated by altering the height of a Cura slice with a Python script. Should anyone wish to do this themselves in Cura, change the orientation of the bottom layers to be 90 degrees, and then set the outer walls to zero to yield the back and forth pattern.

The bed and nozzle temperatures are 60 C and 200 C respectively. The retraction distance is set to 1.25 mm (that's a direct drive appropriate value, but not much retraction is done in this gcode).

To use, print and then measure with some calipers how far from the bottom edge (where the nozzle is the lowest) the ideal first layer offset is. You want no gaps without too much squish (you can actually see the width of the lines vary a little with the raising of nozzle height).

0.4 mm and 0.6 mm nozzle versions are included.

The new nozzle offset adjustment formula for the 0.4 mm nozzle version is:

adjustment_0.4 = (-0.1 mm) + (0.1mm)*(dist from bottom) / (9.4 mm)

simplifying and omitting units:

adjustment_0.4 = (dist from bottom) / 94 - 0.1

The new nozzle offset adjustment formula for the 0.6 mm nozzle version is:

adjustment_0.6 = (-0.1 mm) + (0.1mm)*(dist from bottom) / (9.3 mm)

simplifying and omitting units:

adjustment_0.6 = (dist from bottom) / 93 - 0.1

Here is an example, using the 0.6mm version:

If the best looking row is 5.2 mm from the bottom edge, the adjustment would be

adjustment_0.6 = (5.2) / 93 - 0.1 = -0.044086021505376

I find it easiest to just paste the formula in a web browser bar and have it compute the value.

This is a generic version, just add your printer's specific initialization and finalization gcode. If you create a test pattern for your model of machine, please post it as a remix so others can use it too. Thanks!

Before using this, make sure your nozzle's height has been approximately dialed in. Otherwise, in theory it could hit the bed if your nozzle is set much too low. Additionally, it is presumed that your printer's ABL has been set up properly so the minor Z offsets will be useful for refining the nozzle height.