Start sequence way too long (and redundant?)

Bambu Lab A1 Series General Discussions
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Hello,

This is my first post in this forum.
I have had my A1 for a week now. But it is not my first 3D printer. That was an Elegoo Neptune 3 Pro connected to an Octo.

First conclusion: The A1 is of course worlds better, but I felt more in control with the Neptune.

My biggest question mark is the start Gcode. Even if you switch off flow control and bed leveling, the start phase takes around 4 minutes. Once you’ve set up your filament properly, that’s not such a problem. But the Neptune with its simple Marlin was quicker. You printed a test obje (I use my own, as they fit my usage profile better than the usual temp and retract towers) and if something didn’t look good, you printed the next round again with new settings in the slicer.) The A1 always runs its entire start sequence and if you look at how often the temperature of the nozzle is regulated up and down, you can see that there is a lot of redundancy. Setting up the seam properly will therefore take a long time as every run needs 4 minutes for the start sequence alone.

Unfortunately, the start G-code is not easy to understand as Bambu uses a lot of proprietary G/M codes.

How do you deal with this?

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How do you deal with this?

With the art of relaxation and tranqility meditation. Calming music.

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You will come to realize that the start sequence doesn’t need to be observed, as it is generally uneventful. You’ll get used to sending a job and walking away, it just takes a little time to adjust. Kinda like the pain of waiting for an inkjet printer to waste half a tank of ink every time you turn it on :slight_smile:

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@yo.marc I agree with you. I recently got my A1 and it is not my first 3D printer either. Compared to my previous printer, the A1 needs really a long time for preparing and creates also a lot of waste, like the inkjet printers mentioned in the previous comment. Some steps might be necessary and appropriate to achieve the good print quality, but my impression is also that the A1 overdoes it. My previous printer reached almost the same quality (I upgraded because of the larger print volume), did much less of preparation and I had no issues in years. The bigger pain point for me is the created waste and noise, not the invested time.

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You might want to read through this thread then, about some optimised startup g-code, and explanation of what each phase does. :wink:

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I also would like to print faster but don’t really have that deep level of knowledge of g-code but here is my 2c

The default purge amount is 50 mm. In the original post it was changed to 20 whit great succes. Some people in the comments even changed it to 10 or 5 with succes.

But to keep the reliable nature of the Bambu lab printers alive I chose 20mm

I don’t know what the second g1 e50 was for but in the original this value was also changed to 20 so I will do as wel.

I have not tested the g-code on my machine but it does work on p1 and x1 machines. so why not on the a1 series

so to reduce the purge at the start for the a1 series I found the following lines had to be changed:

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 E20 F200 ; was 50 originally

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 E20 F200 ; was 50 originally

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

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Thanks for the hint, I will have a look at the linked thread.

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Thanks for the modified g-code and your post. I had a look at the thread that @pfeerick posted and also had a look at the machine start g-code of the A1.

Even before your post, I also spotted the G1 E50 F200 commands for extrusion. I have changed them on my printer to G1 E10 F200, but only with very limited success. As the extrusion length has changed to 20%, I would expect that the extruded material (“poop”) also reduces approximately to 20%. However, in my case - I am guessing and have not weighed - the extruded volume is still way more than 50%. Not acceptable in my opinion.

@BambuLab
Why do you flush so much material? Even if the material has not been changed. This is really a waste of material (and time)!!

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Lol, no one has time for that haha

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I tested the firmware on my machine aswel and saw the same.
But only when the “use AMs” Button was pressed.
Not using the ams in the settings would lead to less purging.

Maybe the ams has some other setting it is revering to?

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I deal with it by spending more time in the slicer :stuck_out_tongue:

  • cramming as many parts on a single plate as possible
  • optimising the print settings for speed

What helps a tiny bit is having your next plate sliced and ready to print before the printer cools down too much. Pull your print off, flip the plate, hit print.

Other than that, you’re stuck with this unless you modify the start-up gcode in your profile as others suggested