How to lower the nozzle height by 0.2 mm?

Question

Here are the details of my printer:

• Creality Ender 5
• STM32F103RET6
• CR Touch: - Model: ALT04 - CX: 231120001838
• Mainboard: v4.2.7

I’m trying to adjust the nozzle height on my Creality Ender 5 (4.2.7 + CR Touch) to -0.2 mm, so that it’s closer to the bed and the filament adheres properly. However, I haven’t been able to achieve this. I’ve tried several firmwares, both from Creality and compiled from YouTube tutorials, but nothing has worked. Additionally, I haven’t found any specific tutorials for my printer; I’ve only found versions for the Ender 5 PRO and Ender 5 PLUS, but mine is the standard Ender 5. Some people say that the Ender 5 PRO is nearly identical, just with better construction materials, so I’ve also tried several firmwares for that version, but still no success.

Here are the steps I’ve tried:

1. Perform an Auto Home.
2. Run G1 Z0 to check the current position. Normally, it should be X0 Y0 Z0, but I change the Z to Z-0.2, then save it with M500 or through the printer’s screen to store it in the EPROM.
3. To apply this adjustment permanently, I configure M851 Z-0.2, save it, and verify it with M503. Everything seems fine up to this point. I’ve even stopped the printer and reloaded the configuration from the EPROM, which keeps the changes. When I run G1 Z0 again, the nozzle moves to -0.2. However, when I start printing, the nozzle returns to the default position.
4. I’ve also tried leveling the bed using Bed Leveling, creating a mesh to apply height adjustments during printing and saving the settings.
5. When the nozzle is still too high during printing, I’ve tried using the BabyStep Z feature, but it doesn’t seem to work.

What is this??

Current config file: https://github.com/viikktorr/ENDERv5

Answer 1

If you have a touch sensor, using M851 Z-0.2 will not lower the nozzle by 0.2 mm.

If you look into this question and answer: Automatic Bed Leveling (ABL) with a sensor (BLTouch, inductive, capacitive), how does it work?, and this answer: Z Offset on autoleveling sensor setup, you will learn that an offset is used between the trigger point of the sensor and the level of the nozzle height. Probing, especially the triggering, takes place at a distance typically having an offset of 1-3 mm from the nozzle; this offset is set by the M851 G-code, and hence can never have a value of -0.2 mm!

There are far more simpler methods than redefining the offset through the M851 G-code, but this may well be regarded as the best solution if the offset is incorrect. E.g. when no print sticks to the plate because of the too large gap. Sometimes you only need a closer or wider gap for a specific filament.

Simple solutions would be:

• lower the complete G-code of your sliced object through an option in your slicer
• redefine the level in your start G-code with

    G0 Z0   ; Move the head to 0 mm (which is 0.2 mm too far from the bed)
    G92 Z0.2  ; Redefine this to Z = 0.2

However, you now have seem to have created an incorrect Z-offset, so it is advised to first determine the correct Z-offset from the triggering point to the nozzle level. The flashing of firmware versions was totally unnecessary, a simple G-code trick or slicer setting could have saved you a lot of work.