Why am I getting "! Unable to infer active extruder stepper" when trying a pressure advance tuning tower?

Basic Information:

Printer Model: (heavily modified Tronxy x5s)
MCU / Printerboard: (MKS-SKIPR, SKR 1.4)
klippy.log @bottom

I have my extruder defined

TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=.020 EXTRUDER=extruder_three

It gets all the way to the point where it prints the first line of the tower (even prints the prime line just fine) and it gives me this error:

!! Unable to infer active extruder stepper
!! Unable to infer active extruder stepper

printer.cfg

gcode:

SET_VELOCITY_LIMIT SQUARE_CORNER_VELOCITY=1 ACCEL=500

TUNING_TOWER COMMAND=SET_PRESSURE_ADVANCE PARAMETER=ADVANCE START=0 FACTOR=.020 EXTRUDER=extruder_three

G92 E0
G90
G21
M83 ; use relative distances for extrusion


;_FORCE_RESUME_FAN_SPEED
T2 ;removed this, still didn't work
M104 S210 ; set nozzle temperature
; filament start gcode
M106 S0
;LAYER_CHANGE
;Z:0.2
;HEIGHT:0.2
;BEFORE_LAYER_CHANGE
;0.2

G1 E-3.5 F3000
;_SET_FAN_SPEED_CHANGING_LAYER
SET_VELOCITY_LIMIT ACCEL=500
; printing object tower_with_seam.stl id:0 copy 0
EXCLUDE_OBJECT_START NAME=tower_with_seam.stl_id_0_copy_0
G1 X196.978 Y168.016 F12000
G1 Z.4
G1 Z.2
G1 E3.5 F1200 ;<---- FAILS HERE
;TYPE:Inner wall
;WIDTH:0.499999
G1 F3000

Relevant Klippy.log:

toolhead: max_velocity: 300.000000
max_accel: 500.000000
max_accel_to_decel: 1250.000000
square_corner_velocity: 1.000000
Ending tuning test mode
Starting tuning test (start=0.000000 factor=0.020000)
Extruder 'extruder' now syncing with ''
Extruder 'extruder_two' now syncing with ''
Extruder 'extruder_four' now syncing with ''
Extruder 'extruder_three' now syncing with 'extruder'
toolhead: max_velocity: 300.000000
max_accel: 500.000000
max_accel_to_decel: 1250.000000
square_corner_velocity: 1.000000
Unable to infer active extruder stepper
Unable to infer active extruder stepper
bed_mesh fade complete: Current Z: 10.2000 fade_target: 0.0000 

Try:

TUNING_TOWER COMMAND="SET_PRESSURE_ADVANCE EXTRUDER=extruder_three" PARAMETER=<name> START=<value> FACTOR=<value>

Wow, it (seems to be) working, Thanks.
What is the explanation for this? It would accept E movements in my LOAD command even though it wouldn’t print.

  • The SET_PRESSURE_ADVANCE command needs to have the EXTRUDER specified
  • The quotes make sure that SET_PRESSURE_ADVANCE EXTRUDER is interpreted as one command
  • The other arguments like PARAMETER etc belong to the TUNING_TOWER command

Gotcha’, makes sense
Thanks again

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