Hi,
2 years ago I got myself parts for dual extrusion with a
y-splitter like this or
this . The main issue with this system was that the pulling out the filament out of the hot nozzle would leave strings that would hinder feeding the material back in. This was mainly concerning PLA, I also tested ABS which had less stringing but wasn't perfect in that regard.
There were some different approaches:
*cooling the hotend down, so the material is less viscous and therefore disconnects more cleanly, but that took to long and wasn't practical
*pulling out fast or pulling out really slow
*pull out fast and then feeding back in to form a small plug with the stringing or feed in and out in fast succession to achieve the same
*and all combinations thereof
Since the y splitter setup still seems one of the cheapest and simplest systems (at least from the hardware side) I wonder if there has now formed some consesus or if there is more experience with the setup now?
On the other hand it is not encouraging that prusa abandoned this approach for his multi material upgrade. I also never got straight answers from them when i asked how they were dealing with the stringing while the were still working on MMU V1