Need a G30 / Probe then APPLY_PROBE_TO_Z_OFFSET in Start_Print Macro

General Discussion
1

Basic Information:

Printer Model: Custom Delta Printer
MCU / Printerboard: BTT SKR Pico
Host / SBC: Pi Zero 2 W
klippy.log: NA

Describe your issue:

I am looking for help or a macro to simulate the G30 command, or in Klipper, HOME then PROBE then APPLY_PROBE_TO_Z_OFFSET, then begin printing on my delta printer.

I would like to add this to my START_PRINT macro so that no matter what build plate I have, the printer will always probe the bed (Bl Touch) before starting a print job to set Z=0.

It seems my Z=0 drifts slightly (+/- 0.1 mm) due to ambient air temperature changes. This would help getting a good first layer. I use 3 different build plates and the meshes are almost identical, just at different heights due to the thickness differences.

I came across this post that seems like exactly what I am looking for, I just don’t know enough about macros to implement it properly.

I keep my macros in a separate folder and NOT in the printer.cfg folder. Any help on where to set the PROBE macro and the APPLY_PROBE_TO_Z_OFFSET macro would be much appreciated.

Thanks!!!

2

You didn’t provide the basic info requested in the template. “In all cases” does not mean “in all cases except for mine, because I’m special.”

1 Like
3

Hi,

I’m not sure what you mean. If your are referring to the Klippy Log, I didnt think that is relavant since my delta printer works fine, I get no errors. If I create3 a new bed mesh, it will print fine until the ambient air temps change; last two weeks were really hot in Southern California. This is when i started having the issue with nozzle too close to the bed.

Thanks.

4

With help from a great member, I got a macro that does what I was looking for:

I am sharing a macro developed by a very helpful member here ( gaolst):

gcode_macro MEASURE_AND_SET_Z_ZERO

What this macro does is probe the bed in the center only, with a BL Touch prior to each print job; it is embedded in my START_PRINT macro (it does not create a bed mesh) .

I have it set to probe the bed 10 times then average the results, once bed and nozzle are at temp, the print begins.

I have this running on a delta printer using a BL Touch probe. I wanted this macro to verify bed height before printing because I would get Z-height drift and have to baby-step at the start of each print. this macro eliminates that. This macro can be modified to use different probe type such as a micro switch.

Here is the macro:

[gcode_macro MEASURE_AND_SET_Z_ZERO]
gcode:
  G90
  #pre position toolhead for probing
  G0 X0 Y0 Z80 F2000
  PROBE
  QUERY_PROBE
  ALIGN_PROBE_TO_Z_OFFSET

[gcode_macro ALIGN_PROBE_TO_Z_OFFSET]
description: Query last probe result and align Z height to configured probe.z_offset
gcode:
    {% set z_probe = printer.probe.last_z_result|float %}
    {% set z_offset = printer.configfile.settings.bltouch.z_offset|float %}
    {% set z_delta = z_probe - z_offset %}
    {% set z_position = printer.toolhead.position.z|float %}
    {% set new_z_position = z_position - z_delta %}

    {action_respond_info(
        "Probe result: %.2f \n"
        "Configured Z_offset: %.2f \n"
        "Delta: %.2f \n"
        "Current Z:%.2f \n"
        "New Z:%.2f " % (
            z_probe,
            z_offset,
            z_delta,
            z_position,
            new_z_position))}

    G92 Z{new_z_position}
    #SET_GCODE_OFFSET Z={z_delta}

Here it is referenced in my START-PRINT macro:

[gcode_macro START_PRINT]
gcode:
    # For PLA
    {% set BED_TEMP = params.BED_TEMP|default(70)|float %}
    {% set EXTRUDER_TEMP = params.EXTRUDER_TEMP|default(205)|float %}
    M140 S{BED_TEMP}
    # Use absolute coordinates
    G90
    # Reset the G-Code Z offset (adjust Z offset if needed)
    SET_GCODE_OFFSET Z=0.0
    # Home the printer
    G28
    # default bed mesh is PEI_BuildTak plate
    BED_MESH_PROFILE LOAD=default
    MEASURE_AND_SET_Z_ZERO
    # Move the nozzle near the bed
    G1 Z20 F3000
    # Wait for bed to reach temperature
    M190 S{BED_TEMP}
    # Set and wait for nozzle to reach temperature
    M109 S{EXTRUDER_TEMP}

And here are my printer.cfg BL Touch settings (BTT Pico board):

[bltouch]
sensor_pin: ^gpio22
control_pin: gpio29
pin_move_time: 0.680
stow_on_each_sample: True
probe_with_touch_mode: False
x_offset: 0.0
y_offset: 30.0
#z_offset: 1.090
speed: 3.0
lift_speed: 3.0
samples: 10
sample_retract_dist: 4.0
samples_result: average
samples_tolerance: 0.100

If you need help setting this up, feel free to reach out to me.