Saving and adjusting per-build-surface Z offsets

Macros
1

I have a couple of different build surfaces I use, and they require different Z offsets. On one side of my flex plate I have a textured PEI surface, and on the other a smooth PEI sheet. I found setting and storing the Z offset to be really tedious. Fortunately I was able to use the menu system to build a system for choosing a build surface from a preconfigured list, save the Z offset during live tuning, and apply the offset automatically at the start of a print. I’m using the save_variables config option; modification to these variables via the SAVE_VARIABLE command are applied immediately and accessible when referencing the printer.save_variables.variables dict.

Changing the bed surface and applying its stored Z offset is as simple as going to the Setup menu on your attached display and choosing from the Bed: list.

setup

printer.cfg 

[save_variables]
filename: ~/klipper_config/saved_vars.cfg

saved_vars.cfg

Populate bed_surfaces with a list of your print surfaces. These need to be variables, not friendly names; if you’ve got multiple smooth surfaces, name them something like smooth_01 and smooth_02. Note the format: the value needs to be an eval-able Python string that returns a list of strings.

Set the selected_bed_surface key to one of the entries in the bed_surfaces list, and note the quotes around the value.

For each item in the bed_surfaces list, create a saved variable prefixed with bed_surface_offsets.: these will store the per-surface offset values.

Below is a slightly-formatted version of my current vars file:

[Variables]
bed_surfaces = ['smooth', 'textured']

selected_bed_surface = 'smooth'

bed_surface_offsets.smooth = -0.185
bed_surface_offsets.textured = -0.17

menus

;; choose a bed surface from a pre-configured list
[menu __main __setup __bed_surface]
type: input
name: Bed: { printer.save_variables.variables.bed_surfaces[menu.input | int] }
input: { printer.save_variables.variables.bed_surfaces.index(printer.save_variables.variables.selected_bed_surface) | float }
input_min: 0.0
input_max: { ((printer.save_variables.variables.bed_surfaces | length) - 1) | float }
input_step: 1.0
gcode:
    SAVE_VARIABLE VARIABLE=selected_bed_surface VALUE="'{ printer.save_variables.variables.bed_surfaces[menu.input | int] }'"

;; tunes the Z offset from the setup menu, saves the offset
;; can be performed while not actively printing
[menu __main __setup __offsetz]
type: input
name: Offset Z:{ '%05.3f' % menu.input }
input: { printer.save_variables.variables["bed_surface_offsets." + printer.save_variables.variables.selected_bed_surface] | float }
input_min: -5
input_max: 5
input_step: 0.005
realtime: True
gcode:
    RESPOND TYPE=command MSG="{ 'bed surface: %s, offset: %r' % (printer.save_variables.variables.selected_bed_surface, menu.input) }"
    SET_GCODE_OFFSET Z={ '%.3f' % menu.input } MOVE={ 1 if printer.toolhead.homed_axes == 'XYZ' else 0 }
    SAVE_VARIABLE VARIABLE=bed_surface_offsets.{ printer.save_variables.variables.selected_bed_surface } VALUE={ '%.3f' % menu.input }

;; tunes the Z offset from the tune menu, saves the offset
[menu __main __tune __offsetz]
type: input
name: Offset Z:{ '%05.3f' % menu.input }
input: { printer.gcode_move.homing_origin.z }
input_min: -5
input_max: 5
input_step: 0.005
realtime: True
gcode:
    RESPOND TYPE=command MSG="{ 'bed surface: %s, offset: %r' % (printer.save_variables.variables.selected_bed_surface, menu.input) }"
    SET_GCODE_OFFSET Z={ '%.3f' % menu.input } MOVE=1
    SAVE_VARIABLE VARIABLE=bed_surface_offsets.{ printer.save_variables.variables.selected_bed_surface } VALUE={ '%.3f' % menu.input }

PRINT_START gcode

gcode:
    {% set svv = printer.save_variables.variables %}

    …

    ;; apply Z offset for configured bed surface
    RESPOND TYPE=command MSG="{ 'bed surface: %s, offset: %r' % (svv.selected_bed_surface, svv['bed_surface_offsets.' + svv.selected_bed_surface]) }"
    SET_GCODE_OFFSET MOVE=1 Z={ '%.3f' % (svv["bed_surface_offsets." + svv.selected_bed_surface] | float) }

    …
2

Great to see save_variables being used in the real world. This was my first python project :smile:

3 Likes
3

I love it! I find it super useful and it’s a much more flexible system than writing bytes to eeprom! I do kind of wish it was using json for storage, but this format is certainly consistent with the other config files. Thank you for your work!

4

Glad you like it. Could not have done it without Kevin’s help though.

5

So the way you have this set up, are the values (both negative) listed in the Variables being added to the existing Z offset value already set in printer.cfg?

6

Yes. The offset is fed directly to SET_GCODE_OFFSET: G-Codes - Klipper documentation

7

Will this work if you don’t have an attached display?
I have a v0.1 with no display, but use an old phone to access the Mainsail web interface while at the printer.

8

What’s posted here is kind of tied to the display, unfortunately. I did do some refactoring, however, after I had to yank the display off my printer.

[gcode_macro SET_BED_SURFACE]
description: stores and optionally activates the gcode offset for a given bed surface
gcode:
    {% set svv = printer.save_variables.variables %}

    {% set BED_SURFACE = params.NAME | default(svv.selected_bed_surface) %}
    {% set Z_OFFSET    = params.OFFSET | default(printer.gcode_move.homing_origin.z) | float %}
    {% set MOVE        = params.MOVE | default(0) | int %}

    {% set OLD_Z_OFFSET = svv['bed_surface_offsets.' + BED_SURFACE] | default("unknown") %}

    SAVE_VARIABLE VARIABLE=selected_bed_surface VALUE="'{ BED_SURFACE }'"
    SAVE_VARIABLE VARIABLE=bed_surface_offsets.{ BED_SURFACE } VALUE={ '%.3f' % Z_OFFSET }

    RESPOND TYPE=command MSG="{ 'bed surface: %s, offset: %r -> %05.3f' % (BED_SURFACE, OLD_Z_OFFSET, Z_OFFSET) }"

    SET_GCODE_OFFSET Z={ '%.3f' % Z_OFFSET } MOVE={ MOVE }

With SET_BED_SURFACE you can just use the standard baby-stepping buttons/macros to set the offset, and then call SET_BED_SURFACE NAME=smooth to save the current offset value for the smooth surface, and it sets the smooth surface as the selected one. You can run that macro from your Klipper/Moonraker interface of choice.

2 Likes
9

It will be added to the existing offset? So it will not be set to this absolute value, whatever the current value is?

10

I made a version of this that works like the Prusa firmware. I missed the way my MK3S worked. Build Sheet Manager & "Adjust Live Z" - #2 by garethky
It’s similar to this macro but with some important differences:

  • you don’t have to edit the save variables file, everything, including creating a new sheet is through commands.
  • you can use human readable names for build sheets
  • a macro overrides SET_GCODE_OFFSET to capture baby stepping moves. This works with all of the front ends.
  • baby stepping moves are auto saved to the sheet. No need to remember to save or run an additional command. (This is the Prusa magic)
  • it knows the difference between baby stepping and regular z offset adjustments and it only records baby stepping.
  • it works with CALIBRATE_Z because it’s not an absolute offset. Think of it as storing the amount of “squish” you want per sheet.
  • I worked out the right JINJA incantation to store the values as JSON objects.
2 Likes