No-Nonsense fan duct upgrade for Ender 3

thingiverse

This is a simple "no-nonsense" replacement for the stock print cooling fan duct on the Ender 3, which leaves a bit to be desired. The stock part directs most of its air at the height of the nozzle, rather than on the already-printed material, and is offset significantly from center with the nozzle. I've tried another fan duct replacement, the well-known [vent ring](https://www.thingiverse.com/thing:2912394), and had bad results. Concentrating the air flow with tiny openings very close to the print actually caused it to warp small details just from the air pressure. So I set out to design something that gets more of the air flow across the just-printed material, but without focusing it. This is my first version of the fan duct that actually seems to work. With it I can print M8x1.25 bolt threads in PLA, vertically, with minimal curling/warping, less than 3 seconds per layer (no slowdown for min. layer time). This design isn't perfect; I still get some curling on the side opposite the fan in very fast prints with some designs. Initially I tried bringing half of the air flow around the other side of the nozzle, but wasn't able to get it to flow well. I have no background in fluid dynamics, so this is all trial and error. If anyone has suggestions in the comments for how to adapt this design to bring air flow to both sides, or wants to try modifying it, go for it. The OpenSCAD source is included, and isn't particularly pretty much less parametric, but at least it's simple.