Introduction

Printer Side

My investigations in how to print and get to a mid-print filament change such that I could change colour led me to have to put some more configs in the printer. My printer being an Elegoo Neptune 4 Pro, it runs Klipper. Apparently it does not natively come with support for the G-code M600 which instructs the printer to do a filament change. And thus it ignores the code and continues.

Reddit led me to this video that explains in more detail. Summary would be that one adds a macro into the printer configs that is then triggered when the M600 is present.

There are many more macros that the community has created. In my case, I have no need just yet for the rest of them. The GitHub is here. The relevant code to add to printer.cfg is below (as of post date).

######################################################################
# Filament Change
######################################################################

# M600: Filament Change. This macro will pause the printer, move the
# tool to the change position, and retract the filament 50mm. Adjust
# the retraction settings for your own extruder. After filament has
# been changed, the print can be resumed from its previous position
# with the "RESUME" gcode.

[pause_resume]

[gcode_macro M600]
gcode:
	{% set X = params.X|default(50)|float %}
	{% set Y = params.Y|default(0)|float %}
	{% set Z = params.Z|default(10)|float %}
	SAVE_GCODE_STATE NAME=M600_state
	PAUSE
	G91
	G1 E-.8 F2700
	G1 Z{Z}
	G90
	G1 X{X} Y{Y} F3000
	G91
	G1 E-50 F1000
	RESTORE_GCODE_STATE NAME=M600_state

Slicer

There are plenty of resources online, but for my printer, I have to add in post-processing commands in.

Under Extensions > Post-Processing > Modify G-Code
Add script of Filament Change
The main thing is to remember is that the layer change number is when it requests the filament change prior to printing that layer

Another thing to consider is that a shall purge tower is useful such that the tiny bit of built up filament on the head whilst the physical switch over of the reel is happening. I used a small 20mm ring of 1mm thickness to do so successfully.

Mid-Print Filament Change

Introduction

Printer Side

Slicer