Z_offset isn't respected

Basic Information:

Printer Model: Ender 3 Pro
MCU / Printerboard: MKS Robin E3
klippy(15).log (383.1 KB)

I did the bed leveling (bltouch) and the paper test with the resulting z_offest equal to 0.9. After that, I start printing and hotend scratches the bed. This is very strange if a z_offset is correct, so I performed another test changing the z_offest to 2.4 to check if something might change. The result is the same, hotend still scratches the bed.

The klippy.log shows the correct z_offset value (first 0.9 and 2.4 after manual change) and I don’t know what’s wrong. It looks like at the beginning of printing, the hotend is not adjusted to z_offset and bed leveling values.

You increased the offset, so it will try to go even lower. 2.4 means it moves another 2.4mm down after the sensor triggered.

Also make sure the z_offset isn’t also set in the grayed out area at the bottom of the file. That one will take priority over the one in the main config above.

So, why the 0.9 (result from the paper test) doesn’t work?

If I change it to 0, the hotend starts printing around 1-2 mm over the bed which is incorrect.

If I set it to 0.1, the hotend scratches the bed.

For me, it looks like any value (other than 0) doesn’t work at all.

I have a Creality BLTouch, and it’s mounted with an 8mm height difference as described in the instructions.

I’m so confused about it.

This seems odd. A genuine BLTouch has the following parameters that should be closely followed or otherwise it will deliver crappy results:


In my instructions, the mentioned 8mm is measured from a plastic corpus to the end of the hotend so this picture is pretty similar. If you add a 4 mm probe height to 4.3 mm it’s around 8 mm.

Do you have a link?

It was a paper one, I don’t have it anymore. But the dimensions are the same as on the above picture

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