Feature Request - Ability to disable initial purge at print start


It would be very nice if there was an additional option “Purge filament before print yes/no” (like “Use AMS yes/no” or “Flow calibration yes/no” which we currently can select at the start of a print). With this we could easily avoid too much waste even though we didn’t change the filament between prints. Let’s say last print was green PLA from Bambu and I do want to print the next item(s) with the same filament, then there is definitely no need for purging the old filament and creating waste at all. Or introduce a new print option “Purge always or ask” so that one can decide if being asked or not about this.

Besides, keep up the great work! The machine and software experience is absolutely awesome!



So there are multiple things that happen at start.

  • purge for color change
  • purge and wipe to clean nozzle
  • nozzle load line (across the front of the plate) to make sure there is good flow before starting the print
  • flow calibration using lidar on the X1

All of these can be controlled by editing the start gcode. There is also another discussion about this type of thing, and a related issue logged on GitHub.

I know I can edit the Gcode, but I simply don‘t want to mess with the profiles! Simple as that. Bambu has done a great job in simplifying the whole process and I think, a simple and manufacturer based solution to this would be the best for every user, the newbie and the advanced :wink:


Totally agree. Wasting filament is unnecessary and not really in line with looking after the planet.
Love the printer but please fix this.


3D Printing is entirely the wrong hobby for people concerned about wasting plastic. If you want to save plastic, unplug your printer.

I don’t know how this doesn’t trigger everyone’s self-reflection. I’m all for trying to reduce spool waste, and all that massive industrial-scale stuff, but like a quarter of a gram of purge is nothing compared basically everything you’ve ever printed.

The overwhelming majority of 3D printers out there aren’t saving lives. They’re printing trinkets. I’m sorry, but the sanctimoniousness is tiresome.

We’ve all chosen to work with plastic. Anyone interested in saving the world, probably should have chosen woodworking.


I’m just a cheapskate and trying to save a few cents where I can

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I’m trying to save my time, not plastic. I use the modified start g-code from Nairod and it works great when trying to dial something in. You can save it as a separate printer profile so you only use it when you want to.

I recently printed the same little ASA test piece with 65° overhangs like 30 times in a row trying to dial in the slicer settings. This drops the startup time from 7-10min to less than 1min. I tweaked the original code a bit to keep the bed heater on as well so it starts printing almost immediately.

Highly recommend this but I would consider it intermediate to advanced usage. I doubt that Bambu will ever make this option as there is just way to much chance of a user screwing it up. They have to make the default work in all situations.

Hi, I’ve downloaded the FastStart.3mf file from printables but I am not sure what to with it! I see in the Metadata folder there are several 'machine_settings.config files which include “machine_start_gcode” and “machine_end_gcode” lines. Do I copy and paste one of these into the machine G-code when I make a new ‘fast start’ printer setting? Many thanks.

So I’m able to get rid of the L line at the back of the build plate by disabling the last 5 lines of the start gcode. Now I’m just trying to figure out how to get rid of the line at the front of the build plate too.

I know these purge/load/prime lines help ensure a smooth start to the print, but my prints aren’t that picky and I want to avoid the extra work of scraping these thin lines from the build plate (they adhere too well for me and don’t pop away like a big part)…

Any thoughts on getting rid of the line at the front of the plate too? Can it be done by commenting out some more lines in the gcode?

In the “Preview” tab of BS, the bottom slider will show you ever line of gcode for the layer that you select on the vertical right hand layer slider. Very handy for understanding what the printer is doing and learning about gcode.


Thanks JonRymond, got me pointed in the right direction I think.

The gcode line in question seems to be:
G0 X240 E25 F{outer_wall_volumetric_speed/(0.3*0.5) * 60}

But perhaps I should comment out the entire block (below). A bit scary for me as I don’t want to do something that would mess up the machine. Not even sure how to comment out properly. Do I put semicolon or colon (; or :slight_smile: at the beginning of each line or something else? Think this will work?

;===== noozle load line ===============================
M975 S1
G1 X18.0 Y1.0 Z0.8 F18000;Move to start position
M109 S{nozzle_temperature[initial_no_support_extruder]}
G1 Z0.2
G0 E2 F300
G0 X240 E25 F{outer_wall_volumetric_speed/(0.30.5) * 60}
G0 Y15 E1.166 F{outer_wall_volumetric_speed/(0.3
0.5)/ 4 * 60}
G0 X239.5
G0 E0.2
G0 Y1.5 E1.166
G0 X18 E25 F{outer_wall_volumetric_speed/(0.3*0.5) * 60}

Yes a semicolon will comment out the line.

Do be careful commenting out the G1 Z0.2 line as the next section might of code might assume that the nozzle is already in that position.


worked, thanks JonRaymond!

Yes and no. Mostly no. 3D printing’s waste depends greatly on what you print, how well you design, your skill with the slicer and the settings. Please don’t discourage people from minimising waste. 3D printing doesn’t have to be excessively wasteful.

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I’d like to disable the purge between colors too. I tend to not mind mixing up my colors and find it fun.

Is that in the code as well?

this also helps to free up more space on the plate for large prints… i am printing bases to mount art on and need to fill up the plate with as many as possible. Removing the front/right purge lines by commenting out the 5 lines at the bottom of the startup gcode and disabling flow calibration gives me precious extra space.

There is still the nozzle load line at the front of the plate but its useful so I leave it there - however a option to “purge filament before print” would be helpful :)) i understand the issues however as it would have to be a setting thats applied before slicing.

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After carefully reading your post along with Jon’s responses, I’m still not sure specifically which lines of Gcode you commented out. Did you start with G0 X240 E25…? What lines of code other than that? Thank you.
Never mind. I found the lines I need to comment out. For me, it’s 598 and 599. But how do I edit the Gcode. I see it, but how do I open it to edit it? Thanks

In Studio, just type in the window and save as a User preset.

OrcaSlicer is similar, but it has an additional Edit icon that opens a larger window some explanations of the placeholders.

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