Here is a result on a simple box :
Filament change time : 99 (with 400mm³ filament volumetric purge)
With original “Filament change g-code” and original PTFE length : 4h40m
With modified “Filament change g-code” and reduced PTFE length : 3h00m
This is 1h40m less, nearly 35% of printing time reduction 
@DzzD - I would bet that you could sacrifice material and decrease printing time by eliminating the purge tower all together and increasing the amount of flushing if needed, since it poops faster than it can print.
Modified even further to a M6 CHT clone nozzle, you might be able to double that flushing speed, but the CHT may have it’s own problems cleaning out completely with 3 ports.
Of the few multi color prints that I have done, even modified at 50% less flushing volume with the OEM .4mm nozzle, I have not had color bleed even from dark colors to white or clear in PLA.
ETA I have effectively stopped doing multi color prints due to waste, especially if the flushing and purge quantities is triple or more the printing volume. My first lesson was the BL Christmas Cabin and I ended up doubling the number of plates to reduce the number of color changes to only two colors on one plate.
Ok, I have made the pull request to Bambustudio.
EDIT: sorry there was an error in gcode… will post it later
Yes, purge tower is not always requiere when you print large area and when the print start in a non visible area (inner walls), but if you print just a tiny area of one color, like a thin letter on a face) it is requiered to make the nozzle as clean as possible to begin printing with the new filament, would be nice to be able to bumbed the purge tower speed, for now it is 2.5/3s, it could be one second only I think
Ok, here is the new working g-code for “Change filament G-code” in printer settings :
Paste here :
Obviously, no warranty
g-code removed / obsolete, see below for new optimized version
I tried your new gcode, definitely faster but leaves a blob on the print right after the change. Maybe a little to aggressive.
Did you use a purge tower ?, I did not make any test without
Probably it requiere more wipe at the end, (and a retraction that I have maybe removed by error)
No purge tower, usually don’t use them. Just a simple block with two color changes for a test.
Yes I think the added wipe would work.
You can use the smaller one, 1mm³ 2mm width, but I am gonna try to improve the g-code to take care of what you pointed out.
@everybody : having some feedbacks as @leenanj did, from this g-code would be great, as I wont be able to make all requiered tests myself, so I will be able to make the g-code fully reliable/usable and will update my MR/PR to Bambulab Studio accordingly
Please, give me more feedback, printing mutli-color twice faster is a big step forward !
Been using your fast filament changer gcode now on several prints.
Added a purge tower (width 10mm volume 1mm) to catch and blobs.
Along with my shorter PTFE run from the AMS changing filament is now about 50 seconds.
This has been working great.
Probably not anywhere to go from here as far as speeding the change up.
Maybe there are some few things still doable:
(I have posted an issue on Git about this T g-code)
Maybe 10 secondes could be gained again.
And choice between multi-color and monchrome would become definitivly much more easy.
New version, that should not requiere Purge tower !
I did some tests and results seems equivalent as using a purge tower or not, my fault I forget to set back a necessay g-code…
The good news is that is is not slower so without purge tower overall print time wshould be even better happy
I have tried small black text written on white, wich is not the easiest, without any problem.
g-code removed obsolete, please view below for the new one
Thanks for the work on this, will give a test out.
Tried out your newer fast gcode filament changer.
Without a prime tower there was no blobs at all, color transition looked excellent.
Speed was slightly faster than previous gcode.
Had flushing volumes at 1.0 and saw little to no bleeding.
I printed a cone going from clear filament to black and back again.
95s to go from black to clear, 45s from clear to black.
Running flushing volume at 0.5 will yield about 4s more savings in time.
This ones a keeper, Thank You
Many thanks for you feedback, I have done some tests and get good results tool
I did a last modification, here is probably the latest version (I have also updated my MR to Bambu Github) :
I cant post any new images now on the forum … forum block it, but I tried lite green text thinner than 0.4mm over a black backgroung and I cant see any default !
EDIT: now I can post
Printed without purge tower and new filament g-code
What’s your overall PTFE length ?
50 seconds spunds good, but 100 seconds look very slow, did you have to purge more than 650mm³ ? I think that the maximum I have used from black to white was 650mm³
Printer : Change Filament g-code
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 ;** only requiered when printing by object ?! otherwise going + 0.5mm should be enought
M106 P1 S0
M106 P2 S0
;M104 S[nozzle_temperature_range_high] ;** Change temp to max without waiting, waiting would take age for nothing
;M104 S275 ;** Change temp to 275°c without waiting, waiting would take age for nothing
;** Go to cutting current filament position
;**G1 X20 Y50 F24000 ;**doing in two path to avoid problem on cutter actuator
G1 X20 F18000
G1 Y50 F18000
G1 Y-3
{if toolchange_count == 2}
; get travel path for change filament
M620.1 X[travel_point_1_x] Y[travel_point_1_y] F24000 P0
M620.1 X[travel_point_2_x] Y[travel_point_2_y] F24000 P1
M620.1 X[travel_point_3_x] Y[travel_point_3_y] F24000 P2
{endif}
M620.1 E{old_filament_e_feedrate * 3} T{new_filament_temp}
M104 S[new_filament_temp] ; Nozzle will change its temperature while filament is loaded/unloaded
T[next_extruder] ;Cut and change filament
M620.1 E{new_filament_e_feedrate * 3} T{new_filament_temp}
{if next_extruder < 255}
G92 E0 ;** reset extruder pos, perfect after T
{if flush_length_1 > 1}
; FLUSH_START 1
{if flush_length_1 > 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 - 22.7) * 0.25} F{old_filament_e_feedrate * 1.5}
G1 E0.2 F120
G1 E{(flush_length_1 - 22.7) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.2 F120
G1 E{(flush_length_1 - 22.7) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.2 F120
G1 E{(flush_length_1 - 22.7) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.2 F120
{else}
G1 E{flush_length_1} F{old_filament_e_feedrate * 1.5}
{endif}
; FLUSH_END
{endif}
{if flush_length_2 > 1}
; FLUSH_START 2
G1 E{(flush_length_2 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_2 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_2 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_2 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
; FLUSH_END 2
{endif}
{if flush_length_3 > 1}
; FLUSH_START 3
G1 E{(flush_length_3 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_3 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_3 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_3 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
; FLUSH_END 3
{endif}
{if flush_length_4 > 1}
; FLUSH_START 4
G1 E{(flush_length_4 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_4 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_4 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
G1 E{(flush_length_4 - 1) * 0.25} F{new_filament_e_feedrate * 1.5}
G1 E0.25 F120
; FLUSH_END 4
{endif}
;**G1 E2 F{new_filament_e_feedrate} ;Compensate for filament spillage during waiting temperature
G1 E1 F30 ;Compensate for filament spillage during two second
M109 R[new_filament_temp]
M106 P1 S255
G92 E0
G1 E-[new_retract_length_toolchange] F1800
G1 Y255 F18000
G1 X80 F18000
G1 X60 F18000
G1 X80 F18000
G1 X60 F18000;shake to put down garbage
G1 X70 F18000
G1 X90 F18000
G1 Y255 F18000
G1 X100 F5000
G1 Y265 F5000
G1 X70 F18000
G1 X100 F18000
G1 X70 F18000
G1 X100 F18000
G1 X165 F18000;wipe and shake
G1 Y256 ; move Y to aside, prevent collision
G1 Z{max_layer_z + 3} 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
EDIT : g-code updated 26/04/2023
EDIT : g-code updated 28/04/2023
EDIT : g-code updated 08/05/2023
EDIT : g-code updated 24/09/2023
PR made for Bambustudio, if you want to vote
Hi all,
Very interesting topic! (with the same fantastically mad people at work:)
Will give it a go to speed up PLA prints with PETG support interface.
Any recommendations for the purge volume, multiplier and purge tower or not for this combo?
I would advice low because you dont care that PETG melt a little with PLA.
I have exacly the same idea to test PETG as a PLA support or vice-versa let keep us informed of the results
My first tests will be with 100m³
I will start with another little test to get an idea for the best starting point:
https://www.printables.com/model/370605-bambu-lab-x1c-p1p-flushing-volume-calibration
and then focus on getting a clean change from PETG to PLA.
I just did a try and it works perfeclty ! the only donwsiden but that much annoying is that PETG layers interfaces stick better to the part than to the supports.
So after removing suport you have to remove the interfaces that stay a little sticked to the part, easy job, leave a perfect layer, like a first layer on a flat surface
PLA white, PETG green (Obviously interface Z gap == 0), I wouldn’t have believed this works as well as support-W
