Magnetic Filament Monitor for Automatic E-Step Calibration

[T3P3Tony]

@timschneider this is great! Thanks for sharing it

[timschneider]

@T3P3Tony
I was even able to push it a little further. The most pain four our customers is the non-linear-extrusion calibration.

And what should I say, it is even possible to do that with the MFM

non_linear_extrusion_calibration.gcode

if exists(global.nlecalibration)
  set global.nlecalibration = true
else
  global nlecalibration = true

G10 P0 S235 ; sets the temperature
M140 P0 S90 ; set bed temp

M107                                        ; fan off
M144 P0 S1                                  ; activate bed 1 heater
T0                                          ; select tool 0
M98 P"0:/sys/meltingplot/home_if_necessary" ; check homing
G29 S1                                      ; load stored hight map

M83 ; use relative distances for extrusion
G90 ; use absolute coordinates
G21 ; set units to millimeters

M116                                        ; wait for all heaters

G11 ; unretract

G1 Z300                                      ; raise z=20mm

G53 G1 X50 Y50 F14400                       ; move printhead to center

G92 E0                                       ; reset e-steps

M572 D0 S0.0                                 ; disable pressure advance
M592 D0 A0.0 B0.0                            ; disable non-linear-extrusion

M591 D0 P3 C"e1stop" S0 R98:102 E0.2 L25.3           ; enable MFM, but do not trigger event

G4 S5 ; wait for restart of MFM

G91 ; relative moves
; 15mm
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30

; the mfm should be calibrated now

if sensors.filamentMonitors[0].calibrated == null
	echo "Cannot calibrate filament monitor within 15mm - error!"
	M99

G4 S1 ; wait for filament monitor send timeout

var totalCommandedBase = move.extruders[0].rawPosition
var totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F60
G1 X50 E50 F60

G4 S1 ; wait for filament monitor send timeout
echo "F60 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F90
G1 X50 E50 F90

G4 S1 ; wait for filament monitor send timeout
echo "F90 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F120
G1 X50 E50 F120

G4 S1 ; wait for filament monitor send timeout
echo "F120 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F150
G1 X50 E50 F150

G4 S1 ; wait for filament monitor send timeout
echo "F150 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X-50 E50 F180
G1 X-50 E50 F180

G4 S1 ; wait for filament monitor send timeout
echo "F180 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X-50 E50 F210
G1 X-50 E50 F210

G4 S1 ; wait for filament monitor send timeout
echo "F210 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X-50 E50 F240
G1 X-50 E50 F240

G4 S1 ; wait for filament monitor send timeout
echo "F240 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X-50 E50 F270
G1 X-50 E50 F270

G4 S1 ; wait for filament monitor send timeout
echo "F270 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F300
G1 X50 E50 F300

G4 S1 ; wait for filament monitor send timeout
echo "F300 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F330
G1 X50 E50 F330

G4 S1 ; wait for filament monitor send timeout
echo "F330 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F360
G1 X50 E50 F360

G4 S1 ; wait for filament monitor send timeout
echo "F360 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G10                                          ; retract
G10 P0 R0 S0                        ; disable hotend
M140 S0 R0                          ; set bed heater to 0°
M140 P0 S-273.1                     ; disable bed heater
T-1                                          ; unselect tool

set global.nlecalibration = false

The variable nlecalibration is for further use.

non_linear_extrusion_check.gcode

if exists(global.nlecheck)
  set global.nlecheck= true
else
  global nlecheck= true

G10 P0 S235 ; sets the temperature
M140 P0 S90 ; set bed temp

M107                                        ; fan off
M144 P0 S1                                  ; activate bed 1 heater
T0                                          ; select tool 0
M98 P"0:/sys/meltingplot/home_if_necessary" ; check homing
G29 S1                                      ; load stored hight map

M83 ; use relative distances for extrusion
G90 ; use absolute coordinates
G21 ; set units to millimeters

M116                                        ; wait for all heaters

G11 ; unretract

G1 Z300                                      ; raise z=20mm

G53 G1 X50 Y50 F14400                       ; move printhead to center

G92 E0                                       ; reset e-steps

M572 D0 S0.0                                 ; disable pressure advance
M592 D0 A0.003 B0.011 L0.2                   ; enable non-linear-extrusion

M591 D0 P3 C"e1stop" S0 R98:102 E0.2 L25.3           ; enable MFM, but do not trigger event

G4 S5 ; wait for restart of MFM

G91 ; relative moves
; 15mm
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30

; the mfm should be calibrated now

if sensors.filamentMonitors[0].calibrated == null
	echo "Cannot calibrate filament monitor within 15mm - error!"
	M99

G4 S1 ; wait for filament monitor send timeout

var totalCommandedBase = move.extruders[0].rawPosition
var totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F60
G1 X50 E50 F60

G4 S1 ; wait for filament monitor send timeout
echo "F60 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F90
G1 X50 E50 F90

G4 S1 ; wait for filament monitor send timeout
echo "F90 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F120
G1 X50 E50 F120

G4 S1 ; wait for filament monitor send timeout
echo "F120 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F150
G1 X50 E50 F150

G4 S1 ; wait for filament monitor send timeout
echo "F150 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X-50 E50 F180
G1 X-50 E50 F180

G4 S1 ; wait for filament monitor send timeout
echo "F180 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X-50 E50 F210
G1 X-50 E50 F210

G4 S1 ; wait for filament monitor send timeout
echo "F210 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X-50 E50 F240
G1 X-50 E50 F240

G4 S1 ; wait for filament monitor send timeout
echo "F240 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X-50 E50 F270
G1 X-50 E50 F270

G4 S1 ; wait for filament monitor send timeout
echo "F270 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F300
G1 X50 E50 F300

G4 S1 ; wait for filament monitor send timeout
echo "F300 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F330
G1 X50 E50 F330

G4 S1 ; wait for filament monitor send timeout
echo "F330 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G1 X50 E50 F360
G1 X50 E50 F360

G4 S1 ; wait for filament monitor send timeout
echo "F360 " ^ {(1.0-((sensors.filamentMonitors[0].calibrated.totalDistance-var.totalDistanceBase)/(move.extruders[0].rawPosition-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = sensors.filamentMonitors[0].calibrated.totalDistance

G10                                          ; retract
G10 P0 R0 S0                        ; disable hotend
M140 S0 R0                          ; set bed heater to 0°
M140 P0 S-273.1                     ; disable bed heater
T-1                                          ; unselect tool

set global.nlecheck = false

We have a tool which takes the values from that script and will aproximate the A and B factors of the non-linear-extrusion - but it can be done with excel as well. It will safe you alot of measurements

[timschneider]

ok, the above code is not correct.

I thought that sensors.filamentMonitors[0].calibrated.totalDistance is the total measured distance, but in fact, it is just the total commanded distance and the difference between sensors.filamentMonitors[0].calibrated.totalDistance and move.extruders[0].rawPosition is for example the non linear extrusion correction.

I think it is possible to get the current measured distance in mm with the following line:

(sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

and the new code looks like the following:
0:/gcodes/non_linear_extrusion_calibration.gcode

if exists(global.nlecalibration)
  set global.nlecalibration = true
else
  global nlecalibration = true

G10 P0 S235 ; sets the temperature
M140 P0 S90 ; set bed temp

M107                                        ; fan off
M144 P0 S1                                  ; activate bed 1 heater
T0                                          ; select tool 0
M98 P"0:/sys/meltingplot/home_if_necessary" ; check homing
G29 S1                                      ; load stored hight map

M83 ; use relative distances for extrusion
G90 ; use absolute coordinates
G21 ; set units to millimeters

M116                                        ; wait for all heaters

G11 ; unretract

G1 Z300 F3600                               ; raise z=20mm

G53 G1 X50 Y50 F14400                       ; move printhead to center

G92 E0                                       ; reset e-steps

M572 D0 S0.0                                 ; disable pressure advance
M592 D0 A0.0 B0.0                            ; disable non-linear-extrusion

M591 D0 P3 C"e1stop" S0 R98:102 E0.2 L25.3           ; enable MFM, but do not trigger event

G4 S5 ; wait for restart of MFM

G91 ; relative moves
; 15mm
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30

; the mfm should be calibrated now

if sensors.filamentMonitors[0].calibrated == null
	echo "Cannot calibrate filament monitor within 15mm - error!"
	M99

G4 S1 ; wait for filament monitor send timeout

; sensors.filamentMonitors[0].calibrated.totalDistance is including extrusion correction like pressure advance, non linear extrusion and so on ...
; move.extruders[0].rawPosition is the extrusion without correction values
; sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev is the number of measured revolutions

var totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
var totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F60
G1 X50 E50 F60

G4 S1 ; wait for filament monitor send timeout

var currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
var currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F60 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F90
G1 X50 E50 F90

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F90 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F120
G1 X50 E50 F120

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F120 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F150
G1 X50 E50 F150

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F150 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F180
G1 X-50 E50 F180

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F180 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F210
G1 X-50 E50 F210

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F210 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F240
G1 X-50 E50 F240

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F240 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F270
G1 X-50 E50 F270

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F270 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F300
G1 X50 E50 F300

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F300 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F330
G1 X50 E50 F330

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F330 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F360
G1 X50 E50 F360

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = sensors.filamentMonitors[0].calibrated.totalDistance
set var.currentMeasured = (var.currentCommanded / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F360 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = sensors.filamentMonitors[0].calibrated.totalDistance
set var.totalDistanceBase = (var.totalCommandedBase / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G10                                          ; retract
G10 P0 R0 S0                        ; disable hotend
M140 S0 R0                          ; set bed heater to 0°
M140 P0 S-273.1                     ; disable bed heater
T-1                                          ; unselect tool

set global.nlecalibration = false

The output looks like the following:

So i was able to correct the extrusion up to F300 with 2.85mm filament or up to 31.9mm³/s.

[timschneider]

and the code of

0:/gcodes/non_linear_extrusion_check.gcode

if exists(global.nlecheck)
  set global.nlecheck = true
else
  global nlecheck = true

G10 P0 S240 ; sets the temperature
M140 P0 S90 ; set bed temp

M107                                        ; fan off
M144 P0 S1                                  ; activate bed 1 heater
T0                                          ; select tool 0
M98 P"0:/sys/meltingplot/home_if_necessary" ; check homing
G29 S1                                      ; load stored hight map

M83 ; use relative distances for extrusion
G90 ; use absolute coordinates
G21 ; set units to millimeters

M116                                        ; wait for all heaters

G11 ; unretract

G1 Z300 F3600                               ; raise z=20mm

G53 G1 X50 Y50 F14400                       ; move printhead to center

G92 E0                                       ; reset e-steps

M572 D0 S0.0                                 ; disable pressure advance
M592 D0 A0.0 B0.0035 L0.2                       ; enable non-linear-extrusion

M591 D0 P3 C"e1stop" S0 R98:102 E0.2 L25.3           ; enable MFM, but do not trigger event

G4 S5 ; wait for restart of MFM

G91 ; relative moves
; 15mm
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30

; the mfm should be calibrated now

if sensors.filamentMonitors[0].calibrated == null
	echo "Cannot calibrate filament monitor within 15mm - error!"
	M99

G4 S1 ; wait for filament monitor send timeout

; sensors.filamentMonitors[0].calibrated.totalDistance is including extrusion correction like pressure advance, non linear extrusion and so on ...
; move.extruders[0].rawPosition is the extrusion without correction values
; sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev is the number of measured revolutions

var totalCommandedBase = move.extruders[0].rawPosition
var totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F60
G1 X50 E50 F60

G4 S1 ; wait for filament monitor send timeout

var currentCommanded = move.extruders[0].rawPosition
var currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F60 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F90
G1 X50 E50 F90

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F90 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F120
G1 X50 E50 F120

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F120 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F150
G1 X50 E50 F150

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F150 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F180
G1 X-50 E50 F180

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F180 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F210
G1 X-50 E50 F210

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F210 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F240
G1 X-50 E50 F240

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F240 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F270
G1 X-50 E50 F270

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F270 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F300
G1 X50 E50 F300

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F300 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F330
G1 X50 E50 F330

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F330 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F360
G1 X50 E50 F360

G4 S1 ; wait for filament monitor send timeout

set var.currentCommanded = move.extruders[0].rawPosition
set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F360 " ^ {(1.0-((var.currentMeasured-var.totalDistanceBase)/(var.currentCommanded-var.totalCommandedBase)))*100.0} ^ "% error."

set var.totalCommandedBase = move.extruders[0].rawPosition
set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G10                                          ; retract
G10 P0 R0 S0                        ; disable hotend
M140 S0 R0                          ; set bed heater to 0°
M140 P0 S-273.1                     ; disable bed heater
T-1                                          ; unselect tool

set global.nlecheck = false

[OwenD]

@timschneider
Nice work
The only issue I can imagine is if at higher speeds the change in the extrusion is due to the extruder skipping steps rather than just changes in extrusion efficiency that M592 is attempting to compensate for.
That problem exists no matter if you measure with a tape or using the filament monitor, but I think using your automatic system users are less likely to pay close attention and will just accept the readings on face value.
It probably doesn't matter as you'll get bad results when printing above the extruders max flow rate.
Maybe just a warning to the user if the error rate is above X% that the max flow rate may have been exceeded or the nozzle is jammed?
I've always wondered on the value of the MFM because I see a few people struggling with them, but this has me thinking it's time to throw out my simple switch

[o_lampe]

Over at the simpleFOC forum, we also use the 'AS5xxx' mag sensors a lot and there we struggle with a dead-zone around the turning point (0-360°) where the sensor has an hiccup.
I wonder if RRF has the same issue and found a way to deal with it?
In simpleFOC dev-branch we are experimenting with an interpolating smoothingSensor module, also because the I2C sensor is pretty slow /lags behind.
That's maybe not so relevant for slow extruder moves, though.

[timschneider]

@OwenD said in Magnetic Filament Monitor for Automatic E-Step Calibration:

The only issue I can imagine is if at higher speeds the change in the extrusion is due to the extruder skipping steps rather than just changes in extrusion efficiency that M592 is attempting to compensate for.

That is exactly what happened with the F360 values. My rule of thumb is: try to compensate up to about 10%, because that means the extruder has to push at least 10% more, but in reality it's more like 15-20% more.

As for your other thoughts. I use a different technique to make the sensor more robust, as explained here

[timschneider]

The above code will only work in standalone mode firmware 3.4.6.

It seems that the G4 S1 is somehow breaking the var scope from time to time (it will stop working at F150 for the first time with unknown variable ) @dc42

so I use global variables for sbc setup.

if exists(global.nlecheck)
  set global.nlecheck = true
else
  global nlecheck = true

G10 P0 S245 ; sets the temperature
M140 P0 S90 ; set bed temp

M107                                        ; fan off
M144 P0 S1                                  ; activate bed 1 heater
T0                                          ; select tool 0
M98 P"0:/sys/meltingplot/home_if_necessary" ; check homing
G29 S1                                      ; load stored hight map

M83 ; use relative distances for extrusion
G90 ; use absolute coordinates
G21 ; set units to millimeters

M116                                        ; wait for all heaters

G11 ; unretract

G1 Z300 F3600                               ; raise z=20mm

G53 G1 X50 Y50 F14400                       ; move printhead to center

G92 E0                                       ; reset e-steps

M572 D0 S0.0                                 ; disable pressure advance
M592 D0 A0 B0                       ; disable non-linear-extrusion

M591 D0 P3 C"io3.in" S0 R98:102 E0.2 L25.3           ; enable MFM, but do not trigger event

G4 S5 ; wait for restart of MFM

G91 ; relative moves
; 15mm
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30

; the mfm should be calibrated now

if sensors.filamentMonitors[0].calibrated == null
	echo "Cannot calibrate filament monitor within 15mm - error!"
	M99

M400
G4 S1 ; wait for filament monitor send timeout

; sensors.filamentMonitors[0].calibrated.totalDistance is including extrusion correction like pressure advance, non linear extrusion and so on ...
; move.extruders[0].rawPosition is the extrusion without correction values
; sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev is the number of measured revolutions

global totalCommandedBase = move.extruders[0].rawPosition
global totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F60
G1 X50 E50 F60

M400
G4 S1 ; wait for filament monitor send timeout

global currentCommanded = move.extruders[0].rawPosition
global currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F60 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F90
G1 X50 E50 F90

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F90 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F120
G1 X50 E50 F120

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F120 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F150
G1 X50 E50 F150

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F150 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F180
G1 X-50 E50 F180

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F180 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F210
G1 X-50 E50 F210

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F210 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F240
G1 X-50 E50 F240

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F240 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X-50 E50 F270
G1 X-50 E50 F270

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F270 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F300
G1 X50 E50 F300

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F300 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F330
G1 X50 E50 F330

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F330 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X50 E50 F360
G1 X50 E50 F360

M400
G4 S1 ; wait for filament monitor send timeout

set global.currentCommanded = move.extruders[0].rawPosition
set global.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "F360 " ^ {(1.0-((global.currentMeasured-global.totalDistanceBase)/(global.currentCommanded-global.totalCommandedBase)))*100.0} ^ "% error."

set global.totalCommandedBase = move.extruders[0].rawPosition
set global.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G10                                          ; retract
G10 P0 R0 S0                        ; disable hotend
M140 S0 R0                          ; set bed heater to 0°
M140 P0 S-273.1                     ; disable bed heater
T-1                                          ; unselect tool

set global.nlecheck = false

[timschneider]

ok it took me a little longer to get this up, but this is my current version of the initial automatic filament calibration script.
It will automatically calibrate the e-steps and the non linear extrusion.

It will only run in 3.5 and as a macro.

The copyright of the script is

Tim Schneider
Meltingplot GmbH
CC BY-SA

content of 0:/macros/meltingplot/filament-extrusion-calibration

if !exists(global.ignoreMFMevents)
  global ignoreMFMevents = true
else
  set global.ignoreMFMevents = true

var filamentMonitorPin = "e1stop"
var filamentMonitorCircumference = 25.3

var extrusionDistance = 20                  ; distance for e-step calibration

; speeds in mm/s for NLE to test
var extrusionSpeeds = {0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0}

M107                                        ; fan off
T0                                          ; select tool 0
M98 P"0:/sys/meltingplot/home_if_necessary" ; check homing
G29 S1                                      ; load stored hight map

M83 ; use relative distances for extrusion
G90 ; use absolute coordinates
G21 ; set units to millimeters

var currentTool = state.currentTool
var currentHeater = tools[0].heaters[var.currentTool]
var currentTemp = heat.heaters[var.currentHeater].active

if var.currentTemp < 180 || var.currentTemp > 355
  set var.currentTemp = 180 

M291 P"Please set desired filament temperature" R"Filament Temp" S6 L180 H355 F{var.currentTemp}
set var.currentTemp = input
G10 P0 S{var.currentTemp}

M116                                        ; wait for all heaters

G11 ; unretract

G1 Z300 F3600                               ; raise z=20mm

G53 G1 X50 Y50 F14400                       ; move printhead to center

G92 E0                                       ; reset e-steps

M220 S100                                    ; Set speed factor override percentage
M221 S100                                    ; Set extrude factor override percentage
M572 D0 S0.0                                 ; disable pressure advance
M592 D0 A0.0 B0.0                            ; disable non-linear-extrusion

M591 D0 P0
G4 S1
M591 D0 P3 C{var.filamentMonitorPin} S2 R98:102 E0.2 L{var.filamentMonitorCircumference}    ; enable MFM on all moves

G4 S5 ; wait for restart of MFM

G91 ; relative moves
; 15mm
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30

; the mfm should be calibrated now

if sensors.filamentMonitors[0].calibrated == null
  echo "Cannot calibrate filament monitor within 15mm - error!"
  set global.ignoreMFMevents = false
  M99

G4 S1 ; wait for filament monitor send timeout

; start e-step calibration
var totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X{var.extrusionDistance} E{var.extrusionDistance} F30

G4 S1 ; wait for filament monitor send timeout

var currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

var newESteps = {floor(move.extruders[0].stepsPerMm / ((var.currentMeasured-var.totalDistanceBase)/var.extrusionDistance)*100)/100}

set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X{var.extrusionDistance} E{var.extrusionDistance} F30

G4 S1 ; wait for filament monitor send timeout

set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

set var.newESteps = var.newESteps + {floor(move.extruders[0].stepsPerMm / ((var.currentMeasured-var.totalDistanceBase)/var.extrusionDistance)*100)/100}

set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

G1 X{var.extrusionDistance} E{var.extrusionDistance} F30

G4 S1 ; wait for filament monitor send timeout

set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)

echo "Current E-Steps: " ^ {move.extruders[0].stepsPerMm}
set var.newESteps = (var.newESteps + {floor(move.extruders[0].stepsPerMm / ((var.currentMeasured-var.totalDistanceBase)/var.extrusionDistance)*100)/100})
set var.newESteps = floor(var.newESteps / 3.0 * 100)/100
echo "New E-Steps: " ^ var.newESteps

echo >{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-esteps.g"} "; calibration temperature: " ^ var.currentTemp
echo >>{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-esteps.g"} "M92 E" ^ var.newESteps

M92 E{var.newESteps} ; activate new e-steps

; start non linear calibration

G92 E0                                       ; reset e-steps

; https://www.bragitoff.com/2018/06/polynomial-fitting-c-program/
; speed to test
var x = var.extrusionSpeeds
; number of data points
var N = #var.x
; degree of polynomial
var n = 2
; echo "x: " ^ var.x
; echo "N: " ^ var.N
; echo "n: " ^ var.n

; array to store the y-axis data points
var y = vector(var.N, 0.0)

; gather y data points
;set var.y = {0.0, 0.0, 0.0118, 0.0207, 0.0247, 0.0356, 0.0507, 0.0613, 0.0751, 0.0922, 0.1234, 0.1438}

M591 D0 P0
G4 S1
M591 D0 P3 C{var.filamentMonitorPin} S2 R98:102 E0.2 L{var.filamentMonitorCircumference}    ; enable MFM on all moves

G4 S5 ; wait for restart of MFM

G91 ; relative moves
; 15mm
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30
G1 X1 E1 F30

; the mfm should be calibrated now

if sensors.filamentMonitors[0].calibrated == null
  echo "Cannot calibrate filament monitor within 15mm - error!"
  set global.ignoreMFMevents = false
  M99

G4 S1 ; wait for filament monitor send timeout

; sensors.filamentMonitors[0].calibrated.totalDistance is including extrusion correction like pressure advance, non linear extrusion and so on ...
; move.extruders[0].rawPosition is the extrusion without correction values
; sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev is the number of measured revolutions

var i = 0

var first = true
var check = false
var nle_a = 0
var nle_b = 0
var nn = var.n
var success = false
var mean_error = 0.0
var min_error = 100.0
var max_error = 0.0
var s = 0.0

while true
  ; gather y-values for the compensated x-values
  set var.i = 0
  set var.n = var.nn
  set var.mean_error = 0.0
  set var.min_error = 100.0
  set var.max_error = 0.0
  var errors = vector(var.N, 0.0)

  while {var.i < var.N}
    set var.totalDistanceBase = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)
    var comp_f = var.x[var.i] * 60
    if var.check == false && var.first == false
      set var.comp_f = var.comp_f * (1 + var.y[var.i])
    
    var currentCommanded = 100
    G1 X{mod(var.i,2)=0?100:-100} E{var.currentCommanded} F{var.comp_f}
    
    G4 S1 ; wait for filament monitor send timeout
    
    set var.currentMeasured = (sensors.filamentMonitors[0].calibrated.totalDistance / sensors.filamentMonitors[0].calibrated.mmPerRev * sensors.filamentMonitors[0].configured.mmPerRev)
  
    var error = (1.0-((var.currentMeasured-var.totalDistanceBase)/var.currentCommanded))
    set var.min_error = min(var.min_error, var.error)
    set var.max_error = max(var.max_error, var.error)
    set var.errors[var.i] = var.error

    echo "F" ^ {var.comp_f} ^ ": " ^ {var.error*100.0} ^ "% error."

    if var.comp_f < 60 && var.error >= 0.1
      echo "The filament error exceeds the expected value at low speed. This may be due to grinding. Repeating!"
      G1 E-10 F60 ; backoff some filament
      G1 E15 F60 ; extrude some material to get pass the grinding
      continue

    if var.check == false
      set var.y[var.i] = var.error
      if var.y[var.i] < 0.01
        if var.first == true && var.i < 1 && var.y[var.i] < -0.01
          echo "Calibrate E-Steps first."
          M99
        set var.y[var.i] = 0.01

      ; if the error is larger than 10% or more than twice as the previous value - stop 
      if var.y[var.i] > 0.1 || ( var.i > 0 && var.y[var.i-1] > 0.025 && var.y[var.i] > (var.y[var.i-1] * 2))
        if var.first == true && var.i < 1
          echo "Calibrate E-Steps first."
          M99
        set var.N = var.i
        echo "New N: " ^ var.N
        break

    set var.i = var.i + 1
  
  set var.first = false

  var k = 0
  while {var.k < var.N}
    set var.mean_error = var.mean_error + var.errors[var.k]
    set var.k = var.k + 1

  set var.mean_error = var.mean_error / var.N
  echo "mean error:" ^ var.mean_error

  set var.k = 0
  set var.s = 0.0

  while {var.k < var.N}
    set var.s = pow(var.errors[var.k] - var.mean_error, 2.0)
    set var.k = var.k + 1

  set var.s = sqrt(var.s / var.N)
  echo "standard deviation: " ^ var.s

  if var.check
    set var.check = false
    if var.s <= 0.005
      set var.success = true
      break
    elif var.s > 0.005 && var.s < 0.25
      M592 D0 A0 B0
      continue
    else
      set var.success = false
      break

  ; echo "y: " ^ var.y
  
  ; an array of size 2*n+1 for storing N, Sig xi, Sig xi^2, ...
  var X = vector(2*var.n+1, 0.0)
  ; echo "X: " ^ var.X
  
  set var.i = 0
  while {var.i <= (2*var.n)}
    var j = 0
    while {var.j < var.N}
      set var.X[var.i] = var.X[var.i] + pow(var.x[var.j], var.i)
      set var.j = var.j + 1
    set var.i = var.i + 1
  ; echo "X: " ^ var.X
  
  ; the normal argumented matrix
  
  var B = vector(var.n+1, vector(var.n+2, 0.0))
  var Y = vector(var.n+1, 0.0)
  ; echo "B: " ^ var.B
  ; echo "Y: " ^ var.Y
  
  set var.i = 0
  while {var.i <= var.n}
    var j = 0
    while {var.j < var.N}
      set var.Y[var.i] = var.Y[var.i] + pow(var.x[var.j], var.i) * var.y[var.j]
      set var.j = var.j + 1
    set var.i = var.i + 1
  ; echo "Y: " ^ var.Y
  
  set var.i = 0
  while {var.i <= var.n}
    var j = 0
    while {var.j <= var.n}
      set var.B[var.i][var.j] = var.X[var.i+var.j]
      set var.j = var.j + 1
    set var.i = var.i + 1
  ; echo "B: " ^ var.B
  
  set var.i = 0
  while {var.i <= var.n}
    set var.B[var.i][var.n+1] = var.Y[var.i]
    set var.i = var.i + 1
  ; echo "B: " ^ var.B
  
  var A = vector(var.n+1, 0.0)
  ; echo "A: " ^ var.A
  
  ; gaussEliminationLS
  
  var m = var.n + 1
  set var.n = var.n + 2
  
  set var.i = 0
  while {var.i < (var.m-1)}
    ;Partial Pivoting
    set var.k = var.i + 1
    while {var.k < var.m}
      ;If diagonal element(absolute vallue) is smaller than any of the terms below it
      if abs(var.B[var.i][var.i]) < abs(var.B[var.k][var.i])
        ;Swap the rows
        var j = 0
        while {var.j < var.n}
          var temp = var.B[var.i][var.j]
          set var.B[var.i][var.j] = var.B[var.k][var.j]
          set var.B[var.k][var.j] = var.temp
          set var.j = var.j + 1
      set var.k = var.k + 1
  
    ;Begin Gauss Elimination
    set var.k = var.i + 1
    while {var.k < var.m}
      var term = var.B[var.k][var.i] / var.B[var.i][var.i]
      var j = 0
      while {var.j < var.n}
        set var.B[var.k][var.j] = var.B[var.k][var.j] - var.term * var.B[var.i][var.j]
        set var.j = var.j + 1
      set var.k = var.k + 1
    set var.i = var.i + 1
  
  ;Begin Back-substitution
  set var.i = var.m - 1
  while {var.i >= 0}
    set var.A[var.i] = var.B[var.i][var.n-1]
    var j = var.i + 1
    while {var.j < (var.n - 1)}
      set var.A[var.i] = var.A[var.i] - var.B[var.i][var.j] * var.A[var.j]
      set var.j = var.j + 1
  
    set var.A[var.i] = var.A[var.i] / var.B[var.i][var.i]
    set var.i = var.i - 1
  
  set var.nle_a = var.A[1]
  set var.nle_b = var.A[2]

  M592 D0 A{var.A[1]} B{var.A[2]} L0.2
  echo "Test: M592 D0 A" ^ var.nle_a ^ " B" ^ var.nle_b ^ " L0.2"
  set var.check = true

if var.success
  echo "NLE calibration finished!"
  echo "M592 D0 A" ^ var.nle_a ^ " B" ^ var.nle_b ^ " L0.2"
  echo >{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"} "; max F" ^ var.x[var.N-1] * 60 ^ " mm/min or " ^ var.x[var.N-1] * 6.38 ^ "mm³/s"
  echo >>{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"} "; temp: " ^ var.currentTemp ^ " °C"
  echo >>{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"} "; mean error: " ^ var.mean_error
  echo >>{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"} "; min error: " ^ var.min_error
  echo >>{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"} "; max error: " ^ var.max_error
  echo >>{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"} "; standard deviation: " ^ var.s
  echo >>{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"} "M592 D0 A" ^ var.nle_a ^ " B" ^ var.nle_b ^ " L0.2"
else
  echo "NLE calibration falied!"

; end calibration

G10                                          ; retract
G10 P0 R0 S0                                 ; disable hotend
M140 S0 R0                                   ; set bed heater to 0°
M144 P0                                      ; disable bed heater
T-1                                          ; unselect tool

M591 D0 P0                                   ; reset filament sensor
M98 P"0:/sys/meltingplot/machine-override"              ; Load Machine specific overrides

set global.ignoreMFMevents = false

add the following lines to your 0:/sys/filament-error.g

if exists(global.ignoreMFMevents) && global.ignoreMFMevents == true
  M99

and the following to your filament config

if fileexists({"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-esteps.g"})
  M98 P{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-esteps.g"}

if fileexists({"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"})
  M98 P{"0:/filaments/" ^ {move.extruders[0].filament} ^ "/config-auto-nle.g"}

the macro M98 P"0:/sys/meltingplot/machine-override" will reset the filament monitor to its default, so you need to adapt this.

sample output

Another thing I would like to add is pressure advance calibration, as I think, it should be possible to determine the stiffness of the filament with the filament monitor and predict the pressure advance value. Maybe somesome can help here?

Btw. this script helped me to write a simple adaptive temp control in correlation to the extrusion speed, which will crank up the extrusion flow rate upto 30% and make the NLE look linear. Maybe something for the firmware @dc42

content of daemon.g

while true
  if exists(global.initial_temp) == false
    global initial_temp = 0

  if !exists(global.compensated_temp)
    global compensated_temp = 0

  if !exists(global.is_compensated)
    global is_compensated = false

  if !exists(global.filament_extrusion_temp_compensation_factor)
    global filament_extrusion_temp_compensation_factor = 1

  if exists(global.filament_extrusion_temp_compensation) && global.filament_extrusion_temp_compensation
    if ( {move.currentMove.extrusionRate} > 0 )
      if global.initial_temp == 0 || global.compensated_temp != {heat.heaters[1].active}
        set global.initial_temp = {heat.heaters[1].active}

      set global.compensated_temp = global.initial_temp + min({move.currentMove.extrusionRate} * global.filament_extrusion_temp_compensation_factor, 100)
      G10 P0 S{global.compensated_temp} R{global.initial_temp-50}
      set global.is_compensated = true
    elif (global.initial_temp != 0 && {heat.heaters[1].active} != 0 && global.is_compensated)
      G10 P0 S{global.initial_temp} R{global.initial_temp-50}
      set global.is_compensated = false

if you want to use the temp compensation add the following to your filament config and rerun the auto filament calibration

set global.filament_extrusion_temp_compensation_factor = 8

if !exists(global.filament_extrusion_temp_compensation)
  global filament_extrusion_temp_compensation = true

[AndyE3D]

I created this macro to use the mfm to calibrate non linear extrusion. Have done nearly no print tests to see if it actually have a print quality improvement though so feedback would also be appreciated.

; Inputs
var tool = param.T
var maxSpeed = exists(param.S) ? param.S : 20
var dist = exists(param.D) ? param.D : 20
var minExtrusionThreshold = exists(param.E) ? param.E : 0.85

var force = exists(param.F) ? param.F : 0   ; if > 0, will run macro without confirming with user

; Configuration
var baseSpeed = 1
var debug = false

; Internal variables
var originalTool = state.currentTool
var speeds = {1 ,1 ,1 ,1 ,1 ,1 ,1 ,1 ,1 ,1}
var speedInc = var.maxSpeed / #var.speeds
while (iterations < #var.speeds)
    set var.speeds[iterations] = var.speedInc * (iterations + 1)

var drive = tools[var.tool].filamentExtruder
var flows = var.speeds ; must be same length as var.speeds
var eMulti = var.speeds ; must be same length as var.speeds
var numMeasurements = 0

; Check with user
if (var.force <= 0)
    var msg = "Would you like to calibrate non linear extrusion for T"^{var.tool}^"? Current coefficients: Base="^move.extruders[var.drive].factor * 100^"%, A="^move.extruders[var.drive].nonlinear.a^", B="^move.extruders[var.drive].nonlinear.b
    M291 S4 R{"Calibrating Extrusion: T"^var.tool} P{var.msg} K{"Yes", "No", "Reset Coefficients"}

    if (input == 1)
        M99                         ; exit
    if (input == 2)
        M221 D{var.drive} S100
        M592 D{var.drive} A0 B0
        M99                         ; exit

; Calibrate default extrusion percentage
if (#var.speeds != #var.eMulti)
    abort "var.speeds must have the same length as var.eMulti"

echo "Calibrating extrusion rate for T"^var.tool^" using filament \""^move.extruders[tools[var.tool].filamentExtruder].filament^"\""
echo "Settings: distance = "^var.dist^"mm, base speed = "^var.baseSpeed^"mm/s, min extrusion threshold = "^{var.minExtrusionThreshold * 100}^"%"
echo "Speeds: "^var.speeds^" mm/s"

if (sensors.filamentMonitors[var.drive].type != "rotatingMagnet")
    abort "Must be a rotating magnet encoder"
if (sensors.filamentMonitors[var.drive].enableMode != 2)
    abort "Encoder mode must be S2"
if (sensors.filamentMonitors[var.drive].configured.allMoves != true)
    abort "Encoder must be active for all moves (A2)"

T-1
T{var.tool} P0      ; don't run tpre, tfree, tpost
M703
if (tools[var.tool].active[0] == 0)
    M568 P{var.tool} S{global.defaultFilamentTemperature}
M116 P{var.tool}
M220 S100                   ; reset speed
; M221 D{var.drive} S100      ; reset base extrusion
M592 D{var.drive} A0 B0     ; reset non linear extrusion
; G1 X334 Y100 F30000
M591 D{var.drive} S2 A1  ; set magnetic encoder to record during all moves
M400
G1 E{var.dist} F{var.baseSpeed * 60}
M400
var flow = sensors.filamentMonitors[var.drive].lastPercentage / 100
var baseFlowModifier = {100 / var.flow}
echo "Setting base extrusion factor override for drive "^var.drive^" = "^var.baseFlowModifier
M221 D{var.drive} S{var.baseFlowModifier}

; Collect non linear data
while iterations < #var.speeds
    ; clear encoder data
    M591 D{var.drive} S0
    M591 D{var.drive} S2

    G1 E{var.dist} F{var.speeds[iterations] * 60}
    M400
    set var.flow = sensors.filamentMonitors[var.drive].lastPercentage / 100
    set var.flows[iterations] = var.flow
    set var.eMulti[iterations] = 1 / var.flow
    echo "Flow at "^var.speeds[iterations]^"mm/s = "^{var.flow * 100}^"%, requires extrusion multiplier of "^{var.eMulti[iterations] * 100}^"%"

    set var.numMeasurements = iterations + 1
    if (var.flow < var.minExtrusionThreshold)
        break

echo "Number of measurements = "^var.numMeasurements
echo "Flows: "^var.flows
echo "Required extrusion multipliers: "^var.eMulti

; Quadratic regression
; https://www.statisticshowto.com/quadratic-regression/
var x = 0
var y = 1
var x2 = 0
var x3 = 0
var x4 = 0
var xy = 0
var x2y = 0

while (iterations < var.numMeasurements)
    set var.x = var.x + var.speeds[iterations]
    set var.y = var.y + var.eMulti[iterations]
    set var.x2 = var.x2 + (var.speeds[iterations] * var.speeds[iterations])
    set var.x3 = var.x3 + (var.speeds[iterations] * var.speeds[iterations] * var.speeds[iterations])
    set var.x4 = var.x4 + (var.speeds[iterations] * var.speeds[iterations] * var.speeds[iterations] * var.speeds[iterations])
    set var.xy = var.xy + (var.speeds[iterations] * var.eMulti[iterations])
    set var.x2y = var.x2y + (var.speeds[iterations] * var.speeds[iterations] * var.eMulti[iterations])

if var.debug
    echo "x = "^var.x
    echo "y = "^var.y
    echo "x2 = "^var.x2
    echo "x3 = "^var.x3
    echo "x4 = "^var.x4
    echo "xy = "^var.xy
    echo "x2y = "^var.x2y

; add 100% flow at 0 speed
set var.numMeasurements = var.numMeasurements + 1

; a*var.x4 + b*var.x3 + c*var.x2 = var.x2y
; a*var.x3 + b*var.x2 + c*var.x = var.xy
; a*var.x2 + b*var.x + c*var.numMeasurements = var.y

; Because we have normalised the base extrusion multiplier with a slow extrusion rate
; c ~= 1
var c = 1

; Therefore
; a*var.x4 + b*var.x3 = var.x2y - var.x2
; a*var.x3 + b*var.x2 = var.xy - var.x
; a*var.x2 + b*var.x = var.y - var.numMeasurements

; a = (var.y - var.numMeasurements - b*var.x) / var.x2

; ((var.y - var.numMeasurements - b*var.x) / var.x2)*var.x3 + b*var.x2 = var.xy - var.x
; ((var.y - var.numMeasurements - b*var.x)*var.x3 / var.x2) + b*var.x2 = var.xy - var.x

var b = ((var.xy - var.x) - (((var.y - var.numMeasurements)*var.x3)/var.x2))/(var.x2 - ((var.x * var.x3)/var.x2))
var a = ((var.y - var.numMeasurements) - (var.b * var.x))/var.x2

if var.debug
    echo "a = "^var.a
    echo "b = "^var.b
    echo "c = "^var.c

; Note var.a and var.b are flipped because M592 uses the equation (1 + min(L, Av + Bv^2)) which has different coefficients to that uses to solve the quadratic regression
echo "Setting non linear extrusion multiplier with: M592 D"^var.drive^" A"^var.b^" B"^var.a
M592 D{var.drive} A{var.b} B{var.a}

T-1 P0
T{var.originalTool}

; M591 D{var.drive} S1 A1  ; only monitor filament during prints

The main issue I have identified, which I don't think can easily be solved, is that it doesn't account for how much the filament expands coming out of the nozzle from die swell and foaming. So the extruder might be moving the correct quantity of filament, but the filament becomes a lower density once it leaves the nozzle which effectively produces overextrusion. I think a visual based method would be the most comprehensive way to measure this.

[timschneider]

@AndyE3D
Hi, thank you for sharing this alternative method for calibrating the non-linear extrusion with the MFM based on quadratic regression. In any case, your macro looks quite clean and well thought out.

It seems that the macro collects the errors only once, without reevaluating the applied coefficients. Based on my experience, I can say that this approach is insufficient to achieve good values that result in an error of less than 1% across the entire speed range. That’s why I follow this process with my macro:

• The minimum extrusion distance for the measurements should be at least twice as long as the melting zone.
• First, I collect the errors.
• I discard speeds with errors greater than 10%, as corrections would require at least a 20% adjustment, which is not feasible due to slip and grinding.
• I calculate the coefficients using least squares.
• I apply the coefficients.
• I test whether the errors are within acceptable limits.
• If the errors are within limits, I finish.
• If not, I adjust the speed values based on the corrected errors (e.g., an error of 2.5% at 2 mm/sec).
• I recollect errors with the adjusted speeds (e.g., 2.05 mm/sec).
• I recalculate the coefficients.
• I apply the coefficients again.
• I test if the errors are within limits.
• If the errors are within limits, I finish.
• If not, I drop the fastest speed and repeat the process.

Regarding your concerns about die swell or foaming, I can clarify that this is simply an extrusion multiplier in the slicer or filament profile when the non-linear extrusion is calculated using that method.

I am excited to see where the development of the MFM will lead.

Btw. you can find the latest macro of my MFM calibration at https://github.com/Meltingplot/BigPrint/blob/duet-3.5.3-sbc/duet-config/macros/meltingplot/filament-extrusion-calibration