New A1 skipping extruder during prep phase of print

Bambu Lab A1 Series Troubleshooting
1

Hi there! I recently got an A1 during the sale and love it, but it’s been doing something weird at the start of every print; the extruder skips as if it’s trying to feed filament before the hotend heats up. Basically identical to what’s happening in this post on reddit (not my post, exact same issue): https://www.reddit.com/r/BambuLab/comments/1abzl56/extruder_skips_during_the_prep_phase_of_a_print/

Is this a startup gcode issue of some sort? Bambu studio and A1 FW are both the latest, full calibration done after FW update. My mini doesn’t do this, also on current FW.

Thanks in advance for any help!

Here’s the start gcode:

;===== machine: A1 =========================
;===== date: 20240606 =====================
G392 S0
M9833.2
;M400
;M73 P1.717

;===== start to heat heatbead&hotend==========
M1002 gcode_claim_action : 2
M1002 set_filament_type:{filament_type[initial_no_support_extruder]}
M104 S140
M140 S[bed_temperature_initial_layer_single]

;=====start printer sound ===================
M17
M400 S1
M1006 S1
M1006 A0 B10 L100 C37 D10 M60 E37 F10 N60
M1006 A0 B10 L100 C41 D10 M60 E41 F10 N60
M1006 A0 B10 L100 C44 D10 M60 E44 F10 N60
M1006 A0 B10 L100 C0 D10 M60 E0 F10 N60
M1006 A43 B10 L100 C46 D10 M70 E39 F10 N80
M1006 A0 B10 L100 C0 D10 M60 E0 F10 N80
M1006 A0 B10 L100 C43 D10 M60 E39 F10 N80
M1006 A0 B10 L100 C0 D10 M60 E0 F10 N80
M1006 A0 B10 L100 C41 D10 M80 E41 F10 N80
M1006 A0 B10 L100 C44 D10 M80 E44 F10 N80
M1006 A0 B10 L100 C49 D10 M80 E49 F10 N80
M1006 A0 B10 L100 C0 D10 M80 E0 F10 N80
M1006 A44 B10 L100 C48 D10 M60 E39 F10 N80
M1006 A0 B10 L100 C0 D10 M60 E0 F10 N80
M1006 A0 B10 L100 C44 D10 M80 E39 F10 N80
M1006 A0 B10 L100 C0 D10 M60 E0 F10 N80
M1006 A43 B10 L100 C46 D10 M60 E39 F10 N80
M1006 W
M18 
;=====start printer sound ===================

;=====avoid end stop =================
G91
G380 S2 Z40 F1200
G380 S3 Z-15 F1200
G90

;===== reset machine status =================
;M290 X39 Y39 Z8
M204 S6000

M630 S0 P0
G91
M17 Z0.3 ; lower the z-motor current

G90
M17 X0.65 Y1.2 Z0.6 ; reset motor current to default
M960 S5 P1 ; turn on logo lamp
G90
M220 S100 ;Reset Feedrate
M221 S100 ;Reset Flowrate
M73.2   R1.0 ;Reset left time magnitude
;M211 X0 Y0 Z0 ; turn off soft endstop to prevent protential logic problem

;====== cog noise reduction=================
M982.2 S1 ; turn on cog noise reduction

M1002 gcode_claim_action : 13

G28 X
G91
G1 Z5 F1200
G90
G0 X128 F30000
G0 Y254 F3000
G91
G1 Z-5 F1200

M109 S25 H140

M17 E0.3
M83
G1 E10 F1200
G1 E-0.5 F30
M17 D

G28 Z P0 T140; home z with low precision,permit 300deg temperature
M104 S{nozzle_temperature_initial_layer[initial_extruder]}

M1002 judge_flag build_plate_detect_flag
M622 S1
  G39.4
  G90
  G1 Z5 F1200
M623

;M400
;M73 P1.717

;===== prepare print temperature and material ==========
M1002 gcode_claim_action : 24

M400
;G392 S1
M211 X0 Y0 Z0 ;turn off soft endstop
M975 S1 ; turn on

G90
G1 X-28.5 F30000
G1 X-48.2 F3000

M620 M ;enable remap
M620 S[initial_no_support_extruder]A   ; switch material if AMS exist
    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-48.2 F3000
    M400

    M620.1 E F{filament_max_volumetric_speed[initial_no_support_extruder]/2.4053*60} 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]}
M621 S[initial_no_support_extruder]A

M109 S{nozzle_temperature_range_high[initial_no_support_extruder]} H300
G92 E0
G1 E50 F200 ; lower extrusion speed to avoid clog
M400
M106 P1 S178
G92 E0
G1 E5 F200
M104 S{nozzle_temperature_initial_layer[initial_no_support_extruder]}
G92 E0
G1 E-0.5 F300

G1 X-28.5 F30000
G1 X-48.2 F3000
G1 X-28.5 F30000 ;wipe and shake
G1 X-48.2 F3000
G1 X-28.5 F30000 ;wipe and shake
G1 X-48.2 F3000

;G392 S0

M400
M106 P1 S0
;===== prepare print temperature and material end =====

;M400
;M73 P1.717

;===== auto extrude cali start =========================
M975 S1
;G392 S1

G90
M83
T1000
G1 X-48.2 Y0 Z10 F10000
M400
M1002 set_filament_type:UNKNOWN

M412 S1 ;  ===turn on  filament runout detection===
M400 P10
M620.3 W1; === turn on filament tangle detection===
M400 S2

M1002 set_filament_type:{filament_type[initial_no_support_extruder]}

;M1002 set_flag extrude_cali_flag=1
M1002 judge_flag extrude_cali_flag

M622 J1
    M1002 gcode_claim_action : 8

    M109 S{nozzle_temperature[initial_extruder]}
    G1 E10 F{outer_wall_volumetric_speed/2.4*60}
    M983 F{outer_wall_volumetric_speed/2.4} A0.3 H[nozzle_diameter]; cali dynamic extrusion compensation

    M106 P1 S255
    M400 S5
    G1 X-28.5 F18000
    G1 X-48.2 F3000
    G1 X-28.5 F18000 ;wipe and shake
    G1 X-48.2 F3000
    G1 X-28.5 F12000 ;wipe and shake
    G1 X-48.2 F3000
    M400
    M106 P1 S0

    M1002 judge_last_extrude_cali_success
    M622 J0
        M983 F{outer_wall_volumetric_speed/2.4} A0.3 H[nozzle_diameter]; cali dynamic extrusion compensation
        M106 P1 S255
        M400 S5
        G1 X-28.5 F18000
        G1 X-48.2 F3000
        G1 X-28.5 F18000 ;wipe and shake
        G1 X-48.2 F3000
        G1 X-28.5 F12000 ;wipe and shake
        M400
        M106 P1 S0
    M623
    
    G1 X-48.2 F3000
    M400
    M984 A0.1 E1 S1 F{outer_wall_volumetric_speed/2.4}
    M106 P1 S178
    M400 S7
    G1 X-28.5 F18000
    G1 X-48.2 F3000
    G1 X-28.5 F18000 ;wipe and shake
    G1 X-48.2 F3000
    G1 X-28.5 F12000 ;wipe and shake
    G1 X-48.2 F3000
    M400
    M106 P1 S0
M623 ; end of "draw extrinsic para cali paint"

;G392 S0
;===== auto extrude cali end ========================

;M400
;M73 P1.717

M104 S170 ; prepare to wipe nozzle
M106 S255 ; turn on fan

;===== mech mode fast check start =====================
M1002 gcode_claim_action : 3

G1 X128 Y128 F20000
G1 Z5 F1200
M400 P200
M970.3 Q1 A5 K0 O3
M974 Q1 S2 P0

M970.2 Q1 K1 W58 Z0.11
M974 S2

G1 X128 Y128 F20000
G1 Z5 F1200
M400 P200
M970.3 Q0 A10 K0 O1
M974 Q0 S2 P0

M975 S1
G1 F30000
G1 X0 Y5
G28 X ; re-home XY

G1 Z4 F1200

;===== mech mode fast check end =======================

;M400
;M73 P1.717

;===== wipe nozzle ===============================
M1002 gcode_claim_action : 14

M975 S1
M106 S255 ; turn on fan (G28 has turn off fan)
M211 S; push soft endstop status
M211 X0 Y0 Z0 ;turn off Z axis endstop

;===== remove waste by touching start =====

M104 S170 ; set temp down to heatbed acceptable

M83
G1 E-1 F500
G90
M83

M109 S170
G0 X108 Y-0.5 F30000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X110 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X112 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X114 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X116 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X118 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X120 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X122 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X124 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X126 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X128 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X130 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X132 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X134 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X136 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X138 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X140 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X142 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X144 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X146 F10000
G380 S3 Z-5 F1200
G1 Z2 F1200
G1 X148 F10000
G380 S3 Z-5 F1200

G1 Z5 F30000
;===== remove waste by touching end =====

G1 Z10 F1200
G0 X118 Y261 F30000
G1 Z5 F1200
M109 S{nozzle_temperature_initial_layer[initial_extruder]-50}

G28 Z P0 T300; home z with low precision,permit 300deg temperature
G29.2 S0 ; turn off ABL
M104 S140 ; prepare to abl
G0 Z5 F20000

G0 X128 Y261 F20000  ; move to exposed steel surface
G0 Z-1.01 F1200      ; stop the nozzle

G91
G2 I1 J0 X2 Y0 F2000.1
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5

G90
G1 Z10 F1200

;===== brush material wipe nozzle =====

G90
G1 Y250 F30000
G1 X55
G1 Z1.300 F1200
G1 Y262.5 F6000
G91
G1 X-35 F30000
G1 Y-0.5
G1 X45
G1 Y-0.5
G1 X-45
G1 Y-0.5
G1 X45
G1 Y-0.5
G1 X-45
G1 Y-0.5
G1 X45
G1 Z5.000 F1200

G90
G1 X30 Y250.000 F30000
G1 Z1.300 F1200
G1 Y262.5 F6000
G91
G1 X35 F30000
G1 Y-0.5
G1 X-45
G1 Y-0.5
G1 X45
G1 Y-0.5
G1 X-45
G1 Y-0.5
G1 X45
G1 Y-0.5
G1 X-45
G1 Z10.000 F1200

;===== brush material wipe nozzle end =====

G90
;G0 X128 Y261 F20000  ; move to exposed steel surface
G1 Y250 F30000
G1 X138
G1 Y261
G0 Z-1.01 F1200      ; stop the nozzle

G91
G2 I1 J0 X2 Y0 F2000.1
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5
G2 I1 J0 X2
G2 I-0.75 J0 X-1.5

M109 S140
M106 S255 ; turn on fan (G28 has turn off fan)

M211 R; pop softend status

;===== wipe nozzle end ================================

;M400
;M73 P1.717

;===== bed leveling ==================================
M1002 judge_flag g29_before_print_flag

G90
G1 Z5 F1200
G1 X0 Y0 F30000
G29.2 S1 ; turn on ABL

M190 S[bed_temperature_initial_layer_single]; ensure bed temp
M109 S140
M106 S0 ; turn off fan , too noisy

M622 J1
    M1002 gcode_claim_action : 1
    G29 A1 X{first_layer_print_min[0]} Y{first_layer_print_min[1]} I{first_layer_print_size[0]} J{first_layer_print_size[1]}
    M400
    M500 ; save cali data
M623
;===== bed leveling end ================================

;===== home after wipe mouth============================
M1002 judge_flag g29_before_print_flag
M622 J0

    M1002 gcode_claim_action : 13
    G28

M623

;===== home after wipe mouth end =======================

;M400
;M73 P1.717

G1 X108.000 Y-0.5 F30000
G1 Z0.300 F1200
M400
G2814 Z0.32

M104 S{nozzle_temperature_initial_layer[initial_extruder]} ; prepare to print

;===== nozzle load line ===============================
;G90
;M83
;G1 Z5 F1200
;G1 X88 Y1.0 F20000
;G1 Z0.3 F1200

;M109 S{nozzle_temperature_initial_layer[initial_extruder]}

;G1 E2 F300
;G1 X168 E4.989 F6000
;G1 Z1 F1200
;===== nozzle load line end ===========================

;===== extrude cali test ===============================

M400
    M900 S
    M900 C
    G90
    M83

    M109 S{nozzle_temperature_initial_layer[initial_extruder]}
    G0 X128 E8  F{outer_wall_volumetric_speed/(24/20)    * 60}
    G0 X133 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)/4     * 60}
    G0 X138 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)     * 60}
    G0 X143 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)/4     * 60}
    G0 X148 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)     * 60}
    G0 X153 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)/4     * 60}
    G91
    G1 X1 Z-0.300
    G1 X4
    G1 Z1 F1200
    G90
    M83
    M400

M1002 judge_flag extrude_cali_flag
M622 J1

    M900 R
    G90
    G1 X108.000 Y1.0 F30000
    G91
    G1 Z-0.700 F1200
    G90
    M83
    G0 X128 E4  F{outer_wall_volumetric_speed/(24/20)    * 60}
    G0 X133 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)/4     * 60}
    G0 X138 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)     * 60}
    G0 X143 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)/4     * 60}
    G0 X148 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)     * 60}
    G0 X153 E.3742  F{outer_wall_volumetric_speed/(0.3*0.5)/4     * 60}
    G91
    G1 X1 Z-0.300
    G1 X4
    G1 Z1 F1200
    G90
    M400
M623

G1 Z0.2

;M400
;M73 P1.717

;========turn off light and wait extrude temperature =============
M1002 gcode_claim_action : 0
M400

;===== for Textured PEI Plate , lower the nozzle as the nozzle was touching topmost of the texture when homing ==
;curr_bed_type={curr_bed_type}
{if curr_bed_type=="Textured PEI Plate"}
G29.1 Z{-0.02} ; for Textured PEI Plate
{endif}

M960 S1 P0 ; turn off laser
M960 S2 P0 ; turn off laser
M106 S0 ; turn off fan
M106 P2 S0 ; turn off big fan
M106 P3 S0 ; turn off chamber fan

M975 S1 ; turn on mech mode supression
G90
M83
T1000

M211 X0 Y0 Z0 ;turn off soft endstop
;G392 S1 ; turn on clog detection
M1007 S1 ; turn on mass estimation
G29.4
2

Same with me, doesn’t do it during print just the start. FW 01.03.00.00.

3

Does your start gcode look the same as mine? I have another A1 on the way so I’ll update if that one does it as well.

4

Pasted yours and mine in online text comparer. Absolutely the same.

5

I had the same thing, which seems to me like a problem.
The lines in the G-Code which causing this extruder movements are:

M17 E0.3
M83
G1 E10 F1200
G1 E-0.5 F30
M17 D

which located in the “cog noise reduction” phase.

So I just commented the G1 command lines and now it does not do that.
That is, I changed it to:

M17 E0.3
M83
; G1 E10 F1200
; G1 E-0.5 F30
M17 D

After that change everything seems to work okay.
I have no idea what is the purpose of these commands, if someone have an idea or have an official response from Bambu, I’ll be happy to hear.

2 Likes
6

Much appreciated, thanks!

7

I think it is actually normal mine did it out of the box.

8

It shouldn’t be normal though; why have the extruder purposely try to extrude filament if the nozzle isn’t hot enough to do so? Neither of my two A1 minis do that; they use the same extruder/printheads.

Like @Haruki posted, it’s likely an error in the start gcode.

9

Hello.

My A1 did the same thing, and I commented out the 2 digits in the gCode. However, I have always wondered what these 2 steps are supposed to do and what Bambu Lab was thinking.
For anyone wondering what this step in the initialization is for, I found an official statement from Bambu Lab in another forum and that sheds some light.

"Hello

Thank you for your patience. Our R&D department gave the following response. Before bed leveling, the extruder tried to extrude but could not extrude due to insufficient temperature. This is a normal process.

This aim is to extrude a filament section against the hot end, so that the bed auto-leveling data is more accurate. The relatively large print area of the A1 requires better pre-tightening of the hot end, which will not damage the gear after internal testing.

The clicking sound we hear is the sound of the extrusion motor losing step, which is a normal phenomenon.

I hope my answer will help you with the problem you are experiencing.

Please let me know if you have other questions or if I can assist you with anything else. We are here to help you!

Kind RegardsBambu Lab Support"

So, after knowing this finally I use the original Start gCode now again… seems to make sense :wink:

2 Likes
10

Not a problem, but a feature, the printer its checking filament

11

My interpretation of/assumptions about (MIA) above Bambu Lab Support (BLS) response:

From the wiki (A1):
“The eddy current sensor above the hotend will detect whether the nozzle has made contact with the heatbed.”

BLS:
“This aim is to extrude a filament section against the hot end, so that the bed auto-leveling data is more accurate. The relatively large print area of the A1 requires better pre-tightening of the hot end”

MIA:
Not larger than the other Bambu printers but larger than the A1 Mini’s print area (which also uses the eddy current sensor for Z-homing/bed leveling).
Apparently more accurate bed leveling (‘contact’) data is more important for the A1 than the A1 mini (?) because of the larger print area.
The pre-tightening of the hot end is caused by putting pressure (with extruder) on cold filament. This can only be done while the filament is cold and stiff and not when it is hot and soft/molten.

BLS:
“which will not damage the gear after internal testing”

MIA:
While this is probably a clever way to achieve that the hot end stays under some pressure (so the Eddy-current sensor gets more accurate bed leveling data), in general for the extruder it is not advisable to try feeding filament through a cold hot end.
Every time I hear this ticking/grinding extruder sound, it feels unnatural and unhealthy to me. But apparently this is ‘normal’ for how the A1 works.

3 Likes