Hi all, as this thread was recently poped out, I wanted to give what I have used for monthes now, I did not have the wanted free time to update & publish all things I would like to, including this filament change g-code, hope soon to have some more free time.
I may have done some tests & posts elsewhere, but this one work fine for me and is pretty short :
M620 S[next_extruder]A
M204 S9000
{if toolchange_count > 1 && (z_hop_types[current_extruder] == 0 || z_hop_types[current_extruder] == 3)}
G17
G2 Z{z_after_toolchange + 0.4} I0.86 J0.86 P1 F10000 ; spiral lift a little from second lift
{endif}
G1 Z{max_layer_z + 3.0} F1200
; Save/Pullback XX mm filament before cut (as this small part of filament is not yet in the melting area)
; This value may need to be adjusted or removed and I cant guarantee that it will be good choice for all situation
; If modified search and replace all occurrences of "flush_length_1 - xx" by "flush_length_1 - yy (and flush_length_2 3 4 ...)"
G1 E-10 F1800 ;May need to be low as it can make random clog/underextrusions
;Set fan 1 (part cooling) to 100%
;- try to reduce filament spillage while cutting filament and until hotend reach purge bucket;
;- this also make the filament purged more brittle
;- I was not able to determine the best value :
; * lower value make could sticky blobs, more chance that they pop out of the purge bucket orclog it
; * higer value make purged filament like spagetti, and took a lots more space
M106 P1 S256
M106 P2 S0 ; Auxiliary fan set to zéro
;Using M104 rather than M109 make that printer will not wat for the nozzle to reach its final temperature
;Why is it safe ?
;- because hotend is heating very fast
;- because changing filament take ages
;- because temperature for purging do not need to be set precisly
{if new_filament_temp > 142 && next_extruder < 255}
M104 S[new_filament_temp] ; Nozzle will change its temperature while doing other stuff
{endif}
;Fastly go near the filament cutter pusher
G1 X54 F24000
G1 Y0 F24000
{if toolchange_count == 2}
; get/set travel path for change filament
M620.1 X[travel_point_1_x] Y[travel_point_1_y] F24000 P0 ;X=54 Y=0 => probably cutter
M620.1 X[travel_point_2_x] Y[travel_point_2_y] F24000 P1 ;X=54 Y=0 => probably cutter
M620.1 X[travel_point_3_x] Y[travel_point_3_y] F24000 P2 ;X=54 Y=245 (travel_point_3_y = 245) => probably purge bucket
{endif}
M620.1 E F{old_filament_e_feedrate * 3} T{new_filament_temp}
T[next_extruder] ; Cut the filament, purge the remaining old filament, unload old filament & load new filament
M620.1 E F{new_filament_e_feedrate * 3} T{new_filament_temp}
M400
; Purge filament by pulse : the main change from original code is that here :
; - we are using constante time pause between pulse rather than a proportional time based on purge volume. Constant pulse pauses use a lot less time.
; - we use purge filament flow rate higher, it is safe as we are making little pause that let the plastic get molted more before extruding each pulse
{if next_extruder < 255}
; I have always wondering why this part was split in four blocks ?
G92 E0
{if (flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4) > 10}
{if (flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4 - 10) > 10}
; FLUSH_START
{if (flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4 - 10) > 23.7}
G1 E22.7 F{old_filament_e_feedrate * 1.5} ; do not need pulsatile flushing for start part
G1 E0.2 F120
G1 E{((flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4 - 10) - 22.7) * 0.25} F{old_filament_e_feedrate * 1.5}
G1 E0.2 F120
G1 E{((flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4 - 10) - 22.7) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.2 F120
G1 E{((flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4 - 10) - 22.7) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.2 F120
G1 E{((flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4 - 10) - 22.7) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.2 F120
{else}
G1 E{(flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4 - 10)} F{old_filament_e_feedrate * 1.5}
{endif}
{else}
G1 E{(flush_length_1 + flush_length_2 + flush_length_3 + flush_length_4)} F{old_filament_e_feedrate * 1.5}
{endif}
; FLUSH_END
{endif}
;The main change here is that we are extruding very slowly to let time for pressure to be released from the nozzle in addition to the 1 mm extrusion
;This help (IMHO and based on my tests) in making using a purge tower useless
G1 E1 F30 ; Compensate/slow down for filament spillage / pressure during two second
; FLUSH_END
M400
M106 P1 S256
G92 E0
G1 E-[new_retract_length_toolchange] F1800
G1 E-0.5
;I have no clue of what S3 parameter means
M400 S3; this one is required : if it is missing time will be counted as "Sparse/Wall or other Print" time, if it is present time will be couted as "Travel" time
;The followng comment is a TEST COMMENT
;The following line make mess on Bambu Lab printer so it is commented, I don't know why but all
; following moves speed goes down to a very slow speedwhen using this "G1 Y245 F18000"
;G1 Y245 F18000; Actually nozzle seems to be already there but to have a right preview on Bambu Studio it is required to add this move
;/END TEST COMMENT
;The main change here is that as the filament is cooled and brittle we can (try) to break it before wiping the nozzle
;try to break the filament before wiping
G1 Y250 F18000
G1 Y235 F18000
G1 Y250 F18000
G1 Y235 F18000
G1 Y265 F18000
; shake to put down garbage
G1 X80 F18000
G1 X60 F18000
G1 X70 F18000
G1 X90 F18000
G1 X100 F10000 ;wipe and shake
G1 X70 F10000
G1 X100 F10000
G1 X70 F10000
G1 X100 F10000
G1 X125 F10000
G1 Z{max_layer_z + 3.0} F3000
{if layer_z <= (initial_layer_print_height + 0.001)}
M204 S[initial_layer_acceleration]
{else}
M204 S[default_acceleration]
{endif}
{else}
G1 X[x_after_toolchange] Y[y_after_toolchange] Z[z_after_toolchange] F18000
{endif}
M621 S[next_extruder]A
G1 E0.5