prusa mk2s fan nozzle

thingiverse

While struggling to determine ways to enhance cooling in order to prevent overhangs from curling up and knocking over small components of a challenging model, I stumbled upon this: https://www.thingiverse.com/thing:2276997 which claims to improve cooling by blowing air from two sides instead of solely from the front. It didn't fit perfectly, however, since I have a homemade silicone sock on the hot end, so I needed more clearance between the nozzles and the hot end. The other dimensions also seemed to be slightly off, at least on my printer, so I decided to create my own simplified version from scratch. With the combination of this fan nozzle and an extremely low external perimeter speed (10 mm/s) I finally succeeded in printing https://www.thingiverse.com/thing:2719434 without a brim and 0.15 mm layer height, where even the slightest overhang curling will immediately knock the small parts loose. The nozzle was actually usable printed in PLA, but only for PLA prints and probably not long term. I recommend printing it in ABS anyway. It's a quick and easy print and takes just 30 seconds to swap out the stock fan nozzle so it might be worth trying if your overhangs are causing trouble. It really obstructs the view of what's printing so I'll likely only use it when there are difficult overhangs. FreeCAD source is included. I'm still trying to figure out how to make robust parameterized models in FreeCAD. This isn't perfect, but some of the key dimensions can be tweaked by changing their values in the 'conf' spreadsheet if you want a different compromise between airflow and looks and clearances.