I have been diving into the world of dual extrusion on my Taz 6 with Dual v3 tool head. My primary function is to be able to print with support material.
I have found that eSun PLA Pro is a very solid filament and prints great in the Taz. Also, PolySupport material is very compatible with PLA Pro. I wanted to tune the materials so that the prints were clean and did not suffer from oozing. I didnt like the ooze shield option, as it added a lot of time and material (especially on large volume prints). I have been experimenting with and without the prime tower and wanted to see if others in the community had ideas or suggestions to improve dual extrusion prints so I will share what I have done.
So far, I have gotten near perfect prints using custom Start Gcode, custom Extruder End Gcode, and the prime tower, but there is room for improvement. Basically, I played with the temperatures of the PLA Pro and PolySupport to see at what temps they started to solidify enough not to ooze after a 15mm retraction at 25mm/s.
- Add commands to immediately retract 15mm of support material after purge
- Wait for support extruder to cool low enough to not ooze after print bed shear (about 205 C)
This gave me a very clean first layer… no ooze.
Extruder 1 and 2 End Gcode:
- Direct the deactivated extruder nozzel over to the center of one of the prime tower walls (this impedes oozing while the extruder cools and prevents it from creating bulges on the part. It also prevents ooze from the extruder heating up from getting on the part. This command is hard coded and does require an understanding of where the tower is… would be nice if it was parametric!)
- Wait until deactivated extruder too cold to ooze (205 for PolySupport, 190 for PLA Pro)
After the Extruder End Gcode is run, the active extruder should be over the initial temp value and proceeds to prime on the tower. This further eliminates the possibility of ooze from the cooling extruder making it to the part because now its going to get wiped over the tower for several seconds. The prime tower should be large enough to consume enough time to allow the active extruder to reach full temp. I found that a standard 25mm x 25mm tower that has walls 5mm thick worked well. Be sure to take into account the prime tower print speeds. PolySupport worked well at 20mm/s and the PLA Pro was at 40mm/s. (I think Ill try 60 next)
One issue that I noticed with this was by adding a travel command to my Extruder End Gcode to park the cooling extruder over the prime tower wall, I create unnecessary travels to and from the tower every time there is an extruder change. This is because the original gcode is unaware that I am moving the head in my end block, so when it picks up after the end block, it has to run back to the part (where it thinks it left off), then back to the prime tower to print it. This is annoying, and I haven’t figured out a good way to fix it as it would require Cura understanding what the start and stop blocks are doing to optimize the travel paths. I think all it does currently is copy/paste your code blocks. I would be nice if there was a “Park Head Location” option that would allow you to do what I am doing, only Cura could adjust the travels to eliminate the redundant moves.
At any rate, it would be less moves and material than an ooze shield. I am happy with the progress so far and would like to hear from others who have played with this!