G28 Z Homing Problem on MK3S (Nozzle Crashing Into Build Plate

[semih12ysnck-sketch]

Hello — I’m a Prusa MK3S user and I can’t solve this problem.

When I send the G28 command, X and Y are fine, but on Z the nozzle presses too hard into the bed. I can’t calibrate it correctly — each time it measures it presses extra into the bed and the system keeps giving warnings and stopping. I haven’t been able to figure out how to fix it.

Below I give information about my systems and I’m attaching printer.cfg.

Operating system: Debian GNU/Linux (bullseye)
Distribution: MansailOS 1.3.2 (bullseye)

DO NOT EDIT THIS FILE, IT IS A TEMPLATE. THAT YOU NEED TO COPY
Prusa MK3s Klipper Config

The first thing you'll need to do is go through this file and comment out / uncomment
the files and/or settings you need.

You'll be able to print just fine with this config as it is, but it is recommended
that you follow these steps to properly calibrate your printer:

0. Sanity check and PID Tuning: https://www.klipper3d.org/Config_checks.html
1. Pressure Advance: https://www.klipper3d.org/Pressure_Advance.html
2. Skew Correction: https://www.klipper3d.org/skew_correction.html
3. Resonance Compensation: https://www.klipper3d.org/Resonance_Compensation.html

Read more about klipper here: https://www.klipper3d.org/Overview.html

UI
[include mainsail.cfg]
[include fluidd.cfg]

[mcu]
serial: /dev/serial0 # If you are using internal RPI serial port
serial: /dev/ttyACM0 # If you are using RPI via USB connection to printer
restart_method: command

CONTROL BOARD
[include klipper-prusa-mk3s/mk3s/einsy-rambo.cfg]

BASE SETUP
[include klipper-prusa-mk3s/mk3s/display.cfg]
[include klipper-prusa-mk3s/mk3s/steppers.cfg]
[include klipper-prusa-mk3s/mk3s/tmc2130.cfg]

EXTRUSION

Extruder
[include klipper-prusa-mk3s/extruders/prusa.cfg]
[include klipper-prusa-mk3s/extruders/bmg.cfg]

Hotend
[include klipper-prusa-mk3s/hotends/v6.cfg]
[include klipper-prusa-mk3s/hotends/dragon-standard-flow.cfg]
[include klipper-prusa-mk3s/hotends/rapido.cfg]

[extruder]
To tune Pressure Advance see https://www.klipper3d.org/Pressure_Advance.html
default is already set based on hotend, but you can further improve prints by calibrating it to your nozzle and material
pressure_advance: 0.05
nozzle_diameter: 0.4 # Remember to change this if you change nozzle diameter.
pid_Kp: 23.862
pid_Ki: 1.020
pid_Kd: 139.595

copy this from your current setting on Prusa, but make it absolute (removing -)
[probe]
z_offset = 0.945

For faster printing enable
[printer]
max_accel: 3500
max_velocity: 500
#max_accel_to_decel: 2000
max_z_velocity: 30
max_z_accel: 1000

For stealth mode enable

[tmc2130 stepper_x]
interpolate: True
stealthchop_threshold: 80
[tmc2130 stepper_y]
interpolate: True
stealthchop_threshold: 80
[tmc2130 stepper_z]
interpolate: True
stealthchop_threshold: 80

Custom bed mest probes
Prusa has 3x3 or 7x7, you can do any variation you want
[bed_mesh]
speed: 100
probe_count: 4,4

[delayed_gcode bed_mesh_init]
initial_duration: .01
gcode:
BED_MESH_PROFILE LOAD=default

Linear correction
Check extruders/linear-correction for more informations.
[include klipper-prusa-mk3s/extruders/linear-correction/linear-correction-0.cfg] # Default Prusa linear correction optimized for LDO motors

MACROS
[include klipper-prusa-mk3s/macros.cfg]

FIRST RUN:
Execute these sequentially in the console, let PID tuning finish before saving
PID_CALIBRATE HEATER=extruder TARGET=170
SAVE_CONFIG
PID_CALIBRATE HEATER=heater_bed TARGET=60
SAVE_CONFIG

You can also skip the above setting for stock Prusa and use
[extruder]
control: pid
min_temp: 0
max_temp: 305
min_extrude_temp: 170

[stepper_x]
step_pin: PC0
dir_pin: !PL0
enable_pin: !PA7
microsteps: 16
rotation_distance: 32
endstop_pin: tmc2130_stepper_x:virtual_endstop
position_endstop: 0
position_max: 255
homing_speed: 50
homing_retract_dist: 0

[stepper_y]
step_pin: PC1
dir_pin: PL1
enable_pin: !PA6
microsteps: 16
rotation_distance: 32
endstop_pin: tmc2130_stepper_y:virtual_endstop
position_endstop: -4
position_max: 212.5
position_min: -4
homing_speed: 50
homing_retract_dist: 0

[stepper_z]
step_pin: PC2
dir_pin: !PL2
enable_pin: !PA5
microsteps: 16
rotation_distance: 8
endstop_pin: probe:z_virtual_endstop
position_max: 215
position_min: -2
homing_speed: 13.333

[extruder]
step_pin: PC3
dir_pin: PL6
enable_pin: !PA4
microsteps: 16

The end, on the end the printer will store it's tuning data, so do not edit it.

## <---------------------- SAVE_CONFIG ---------------------->
## DO NOT EDIT THIS BLOCK OR BELOW. The contents are auto-generated.
##
## [bed_mesh default]
## version = 1
## points =
## -0.295833, -0.110000, -0.211667, -0.384583
## -0.157500, 0.055000, -0.010833, -0.314167
## -0.187500, 0.046667, 0.020000, -0.108333
## -0.401667, -0.126667, -0.126667, -0.363333
## x_count = 4
## y_count = 4
## mesh_x_pps = 3
## mesh_y_pps = 3
## algo = bicubic
## tension = 0.2
## min_x = 24.0
## max_x = 228.0
## min_y = 6.0
## max_y = 210.0
##
## [probe]
#*# z_offset = 0.500