Extruder resetting after purging

taconite

Hey guys,

in the start-g.code of my sliver (Cura version 4.6). I would like to purge the Hot-End. This why I call a script called "purge_print"
After the filament is pushed the extruder is moving backwards the amount that was pushed in the macro. Setting the extruder to 0 with G92 is not working - now is the big question: Why?

Thank you for your help!

;this file is for purging at start of the print
G1 X-154 Y-83 F10000
G92 E0
G1 E25 F300
G92 E0
G4 P1500


;Brush
G1 X-148 Y-82 F2000
while iterations<0
	G1 X-141 Y-69 F10000
	;G1 X-139 Y-76 F10000
	G1 X-148 Y-82 F15000
G1 X-102 Y-57 F15000

Phaedrux

I suggest you switch Cura to use relative extruder moves instead of absolute if you haven't already. Then no need to reset the extruder position at all.

What do you have in the rest of your slicer start code? Can you share the first 50 lines or so of a sliced file?

taconite

@phaedrux Thank you for your answer

M291 P"Heating up bed than nozzle" R"Preparing Print" T5 ; Display message
G28
M106 P10 S0.25
M190 S{material_bed_temperature}
M106 P10 S0.4
M109 S{material_print_temperature}
G29 S1
M98 P"Alarmsound.g"
G1 Z30 F15000
M98 P"print_purge"
G1 X0 Y0 F18000
G92 E0
M106 P10 S0.5
M291 P"Printing" R"Print..." T5 ; Display message

Cura is on relative extruder moves already. I thought maybe it could be fixed with G92
it is independent from the sliced file, I tried it with multiple files

taconite

;Layer height: 0.1
;MINX:-70.881
;MINY:42.231
;MINZ:0.3
;MAXX:-39.606
;MAXY:72.174
;MAXZ:5
;POSTPROCESSED
;Generated with Cura_SteamEngine 4.6.1
T0
M82 ;absolute extrusion mode
M291 P"Heating up bed than nozzle" R"Preparing Print" T5 ; Display message
G28
M106 P10 S0.25
M190 S80.0
M106 P10 S0.4
M109 S230
G29 S1
M98 P"Alarmsound.g"
G1 Z30 F15000
M98 P"print_purge"
G1 X0 Y0 F18000
G92 E0
M106 P10 S0.5
M291 P"Printing" R"Print..." T5 ; Display message
M83 ;relative extrusion mode
G1 F4200 E-5
;LAYER_COUNT:48
;TYPE:CUSTOM
; Movement of the Toolchanger with every layer
G91 ;relative positioning
G1 U0.1
G90 ;back to absolute positioning
;LAYER:0
M107
G0 F7200 X-44.974 Y45.591 Z0.3
;TYPE:SKIRT
G1 F4200 E5
G1 F3600 X-44.667 Y45.934 E0.02297
G1 X-43.962 Y46.85 E0.05767
G1 X-43.488 Y47.604 E0.04443
G1 X-40.948 Y52.11 E0.25806
G1 X-40.668 Y52.655 E0.03057
G1 X-40.512 Y52.991 E0.01848
G1 X-40.136 Y53.969 E0.05227
G1 X-40.001 Y54.405 E0.02277
G1 X-39.806 Y55.17 E0.03939
G1 X-39.72 Y55.687 E0.02615
G1 X-39.674 Y56.034 E0.01746
G1 X-39.606 Y57.145 E0.05553
G1 X-39.611 Y57.597 E0.02255
G1 X-39.66 Y58.385 E0.03939
G1 X-39.779 Y59.158 E0.03902
G1 X-40.058 Y60.291 E0.05821
G1 X-40.198 Y60.718 E0.02242
G1 X-40.599 Y61.707 E0.05324
G1 X-41.011 Y62.495 E0.04436
G1 X-43.687 Y67.029 E0.26266
G1 X-44.009 Y67.53 E0.02971
G1 X-44.222 Y67.835 E0.01856
G1 X-44.925 Y68.702 E0.05569
G1 X-45.237 Y69.035 E0.02277
G1 X-45.805 Y69.583 E0.03938
G1 X-46.459 Y70.104 E0.04172
G1 X-47.367 Y70.705 E0.05432
G1 X-47.761 Y70.928 E0.02259
G1 X-48.467 Y71.282 E0.0394
G1 X-49.238 Y71.581 E0.04126
G1 X-50.322 Y71.892 E0.05626
G1 X-50.769 Y71.986 E0.02279
G1 X-51.916 Y72.14 E0.05774
G1 X-52.812 Y72.174 E0.04473
G1 X-57.998 Y72.12 E0.25874
G1 X-58.588 Y72.091 E0.02947
G1 X-58.947 Y72.06 E0.01798

Phaedrux

@taconite said in Extruder resetting after purging:

M82 ;absolute extrusion mode M291 P"Heating up bed than nozzle" R"Preparing Print" T5 ; Display message G28 M106 P10 S0.25 M190 S80.0 M106 P10 S0.4 M109 S230 G29 S1 M98 P"Alarmsound.g" G1 Z30 F15000 M98 P"print_purge" G1 X0 Y0 F18000 G92 E0 M106 P10 S0.5 M291 P"Printing" R"Print..." T5 ; Display message M83 ;relative extrusion mode
G1 F4200 E-5

Cura starts with absolute extrusion enabled regardless of what you have configured and only changes to relative extrusion right before it starts the main print.

As you can see from the gcode it starts with M82 and M83 only shows up at the end after your macro has been called followed by a 5mm retraction. So add M83 to the start of your purge macro to ensure it's relative there.

Are you sure it's retracting the full 25mm and not just the -5mm move?

deckingman

@taconite Another thing you can try is adding M400 after the extruder move. This will ensure the move finishes before any other commands are executed.

taconite

@phaedrux ah perfect - thank you! I will try that. I guess in this file I reduced the purging from 25 to 5 so with the skirt I will get material to flow again.

@deckingman alright - will add the M400 aswell!