M620 / m621?

Bambu Lab A1 Series
1

I’m going thru the A1 mini start gcode to build a prusaslicer profile, but I’m not entirely sure about these m620 & m621 commands. This all looks like AMS stuff, which I do not have.

Just hoping someone can tell me exactly what I’m seeing with these weird custom bambu gcodes

M620 M ;enable remap
M620 S[initial_no_support_extruder]A ; switch material if AMS exist
G392 S0 ;turn on clog detect
M1002 gcode_claim_action : 4
M400
M1002 set_filament_type:UNKNOWN
M109 S[nozzle_temperature_initial_layer]
M104 S250
M400
T[initial_no_support_extruder]
G1 X-13.5 F3000
M400
M620.1 E F{filament_max_volumetric_speed[initial_no_support_extruder]/2.405360} T{nozzle_temperature_range_high[initial_no_support_extruder]}
M109 S250 ;set nozzle to common flush temp
M106 P1 S0
G92 E0
G1 E50 F200
M400
M1002 set_filament_type:{filament_type[initial_no_support_extruder]}
M104 S{nozzle_temperature_range_high[initial_no_support_extruder]}
G92 E0
G1 E50 F{filament_max_volumetric_speed[initial_no_support_extruder]/2.405360}
M400
M106 P1 S178
G92 E0
G1 E5 F{filament_max_volumetric_speed[initial_no_support_extruder]/2.4053*60}
M109 S{nozzle_temperature_initial_layer[initial_no_support_extruder]-20} ; drop nozzle temp, make filament shink a bit
M104 S{nozzle_temperature_initial_layer[initial_no_support_extruder]-40}
G92 E0
G1 E-0.5 F300

G1 X0 F30000
G1 X-13.5 F3000
G1 X0 F30000 ;wipe and shake
G1 X-13.5 F3000
G1 X0 F12000 ;wipe and shake
G1 X0 F30000
G1 X-13.5 F3000
M109 S{nozzle_temperature_initial_layer[initial_no_support_extruder]-40}
G392 S0 ;turn off clog detect

M621 S[initial_no_support_extruder]A

2

You will need to change these G-codes for the A1 edits.

…

M140 S[first_layer_bed_temperature] ;set bed temp

M190 S[first_layer_bed_temperature] ;wait for bed temp

M109 S{first_layer_temperature[initial_extruder]}

M104 S[first_layer_temperature[initial_extruder]] ;set extruder temp

M109 S{first_layer_temperature[initial_extruder]-20} ; drop nozzle temp 20c

…

{if filament_type[initial_tool]==“PLA”}
{if (bed_temperature[current_extruder] >45)||(first_layer_bed_temperature[current_extruder] >45)}
M106 P3 S180
{elsif (bed_temperature[current_extruder] >50)||(first_layer_bed_temperature[current_extruder] >50)}
M106 P3 S255
{endif};Prevent PLA from jamming
{endif}

…

M620 S[initial_tool]A ; switch material if AMS exist

M621 S[initial_tool]A

T[initial_tool]
…

Turn off the texture bed plate G-code

;{elsif (curr_bed_type==“Textured PEI Plate”)}
; G29.1 Z{-0.04} ; for Textured PEI Plate
;{else}
; G29.1 Z{0.00} ; for High Temp or Engineering Plate
;{endif}

You can turn stuff off by commenting relative lines like the bed plate above.

…

Filament Settings Start G-code you might want to do something like this also.

M106 P3 S127 ; Chamber fan 0 to 255 on/off by commenting the line
;M106 P2 S78 ; Aux fan 0 to 255 on/off by commenting the line
;G29.1 Z-0.04 ; Textured bed plate on/off by commenting the line

This will get you started if you get any errors on other G-codes just post them.

Bambu Lab Specific G-Code

3

So um what do these actually do though? I’m trying to write my own, more logical startup sequence and I want to make sure I include them correctly (and see if they’re really needed because a lot of things aren’t).

Also, my stock A1 gcode includes the variables like the original, not like these. Do either work then?

And why does the texture plate gcode need to be turned off? I’ve heard that changing the G29.1 Z number from -0.04 to 0.03 helps with PETG and so that’s what I’ve been using and its worked great.

And finally, I thought the A1 and A1 Mini only had one fan that’s controlled by either M106 SXXX or M106 P1 SXXX and not P2 or P3?