Hell of Strings
My MK3s+mmu2s started to have problem lately. I was forced to change the original nozzle to the chinese brass nozzle form trianglelabs, they look well machined. The original nozzle somewhat clogged when I decided to print ABS to see if I can continue printing since PLA been failing on me quite a lot. Turns out it was the old nozzle gave me the problem. Now I have this new problem, stringing everywhere with the new nozzle. Old nozzle didn't have any stringing but somewhat under extrusion a little bit.
I also changed to a generic heatbreak TC4 from china as well (probably true anyway) mmu2s unload sequence after print has finish, the filament deformed in the extruder gear and stuck there.No matter what retraction settings I put, it is just strings everywhere. Stringing reduced at lower temperature but at lower temperature, the printed parts will be very weak.
Left, 1.0mm retraction
center, 1.2mm retraction
right, 1.2mm + 50mm/s retraction
all printed at stock prusa settings, 0.2mm, 215>210'c nozzle
Left, 1.2mm retraction with 195'c nozzle
right, 0.8mm retraction, no z-hop, 215>210'c nozzle
Both are printed with stock prusa 0.2mm settings