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Are you probing enough points?

If your bed is curved or particularly warped you can increase the number of points the probe measures in order to create a more detailed correction matrix (at the expense of time – more probes means G29 takes longer).

Try a 5×5 or 7×7 grid by changing this line in the Configuration.h file of the Unified Firmware:

#define EZABL_POINTS 5

Are your X and Y offsets correct?

For EZABL™ to work correctly it is essential that the printer knows the exact offset from the nozzle to the probe, otherwise, any correction is not going to be applied in the right place, and it may look like the printer isn’t correcting at all.

If you downloaded the Unified Firmware and used one of the mounts we supply these are correct already as we have printed, mounted, and measured them all for you already.

It is absolutely vital that you check the sensor offsets once your probe is installed, and update the values in configuration.h accordingly, you will need to uncomment #define CUSTOM_PROBE and enter them in the configuration.h file.

These are the relevant lines:

#define X_PROBE_OFFSET_FROM_EXTRUDER 10  // X offset: -left  +right  [of the nozzle]

#define Y_PROBE_OFFSET_FROM_EXTRUDER 10// Y offset: -front +behind [the nozzle]

Typically, sensors are most sensitive in the center, so we need to know the offset from the tip of the nozzle to the center of the probe. Here is an approach you can use to measure it:

Measuring X and Y offsets

  1. Home X and Y then move your Z down until the nozzle is on the bed
  2. Move the nozzle to roughly center on the bed and mark where the nozzle was
  3. Cycle the power on the printer to reset the XY position, it should show 0 for each
  4. Now move the head using the Prepare > Move Axis on the LCD (or you can also use your computer to move the axes) until the center of the probe is over where the nozzle was
  5. Look at your X and Y position, these are your offsets.
    1. If the sensor is LEFT of the nozzle the offset is negative (Ex: -10). If it is to the right then the offset is positive (Ex: 10)
    2. If the sensor is in FRONT the nozzle on Y then the offset is negative (Ex: -5). If it is BEHIND the nozzle on Y then the offset is positive (Ex: 5).

The offset parameters are integers, so round your results to whole numbers before updating configuration.h