Geeetech

Do you want to print with 8 colors using 3 extruders? It is possible with simple gcode post-processing.

There are three steps:
1. Add printer to Cura profile. Set 8 extruders.
2. Load stl models (8 independent parts).
3. Assign extruders to each part of model. Do not forget about prime tower.
4. Slice and save to disk.
5. Run script that will replace every Tx with corresponding M163... commands like here:
before:
T1
after:
M163 S0 P0
M163 S1 P1
M163 S2 P0
M164 S0
6. Print.

I wrote script and have printed test squares. My settings for virtual extruders were:
T0: 1.0/0.0/0.0
T1: 0.0/1.0/0.0
T2: 0.0/0.0/1.0
T3: 0.5/0.5/0.0
T4: 0.0/0.5/0.5
T5: 0.5/0.0/0.5
T6: 0.0/0.7/0.3
T7: 0.3/0.7/0.0

I have used following filament: brown, white and blue (yes, it is not the best choice for color mixing but this is the only colors I have at the moment). Result photo (8 small squares): Another test (6 big squares, slightly different settings with prime tower volume increased):

I put the following in the Start G-Code for the printer:

M163 S0 P0.5
M163 S1 P0.5
M163 S2 P0
M164 S3

This assigns the mix to the virtual extruder, running the first test print but seems to be working well. Test print is only one colour so will have to see how it works with multiple colours and the purge bucket setup I have.

I don't know whether I missed something. Is there an advantage to replacing the T0 etc?