Hi folks,
just finished my first dual color print with the dual extrusion head. I started off with Luban, and quickly stopped. Although many Cura settings are by now available in Luban, important ones are missing.
In Cura, I created a new printer with the following settings (not strictly true - I modified start/end code after the print, so take it with a grain of salt):
The extruder start/end-GCode is of no effect, but allows you to locate the extruder changes in the GCode more easily.
My machine start GCode:
G28 ;home
G90 ;absolute positioning
G1 X-10 Y-10 F3000 ;Move to corner
G1 Z0 F1800 ;Go to zero offset
M140 S{material_bed_temperature_layer_0} ;Set Bed Temperature
M109 S{material_print_temperature_layer_0} ;Wait for Hotend Temperature
M190 S{material_bed_temperature_layer_0} ;Wait for Bed Temperature
G92 E0 ;Zero set extruder position
End-GCode:
M140 S0 ;Heated bed heater off
M104 T0 S0 ;Switch off left hotend
M104 T1 S0 ;Switch off right hotend
G90 ;absolute positioning
G1 Z{machine_height} E-1 F3000 ;move Z up a bit and retract filament even more
G1 X0 F3000 ;move X to min endstops, so the head is out of the way
G1 Y{machine_depth} F3000 ;so the head is out of the way and Plate is moved forward
This is partly inspired by the Luban JSON you can find here (Windows 64bit):
C:\Program Files\Snapmaker Luban\resources\app\resources\print-settings\printing\a350_dual
I decided to print without a purge tower (hate to throw away the plastic) and played with retraction. This did not work out perfectly, but I guess with a bit of tuning and tweaking of retraction settings I may get there.
These settings I made visible and set/will play a bit with in the future:
- Retraction distance: This Iāll increase considerably - had it at 3 mm, but will change to 15 mm.
- Retraction extra prime amount: Had this at 0.25 mmĀ³ - will leave it there
- Skirt minimum length: had it at 250 mm - will next time do at least 500 mm. After first nozzle warm up, it takes very long until nozzle pressure is there, since much material has oozed out before. A longer skirt will help to build up pressure.
- Nozzle Switch Retraction Distance: was at 16 mm - I guess Iāll leave it there for the time being. May play around with retraction speedā¦
- Nozzle Switch Extra prime amount; was 0, will set this to 0.25 mmĀ³ next time
The model I printed did not need dual color, it was just because I was eager to test the new print head, so please be not disappointed by the following pictures 
Observations that cause me to test the other settings above:
- The skirt is barely there, because nozzle pressure was too low.
- This also caused considerable under-extrusion on first layer. Later, flow was OK, although I yet did no extruder calibration. Also: Thereās now on-the-fly flow control, yay! But did not use it here.
- With retraction, the nozzle dwells for half a second on the print before tool change. This leaves a scar. I think Iāll try Z-hop with retraction next time. Also, perhaps I can influence the tool change locations to be at invisible places.
- Overall print quality is decent, print cooling good. The print has considerable overhangs, and they came out very well! My linear modules need maintenance - this causes a few imperfections. Do not attribute them to the print head. Btw. print speed was 60 mm/s, itās PLA @205Ā°C and build plate at 60Ā°C. Layer height 0.24 mm.
- The toolhead change is really nice! Snapmaker found a clever solution! Kudos!
I used firmware 1.15.15, no issues so far. Calibration was done a few days earlier, so the calibration settings survived a power cycle.
All in all Iām satisfied - I guess the dual extrusion head and me will become close friends
And here a few pictures:
