No-Nonsense fan duct upgrade for Ender 3

thingiverse

This is a straightforward replacement for the Ender 3 stock print cooling fan duct, which has its drawbacks. The stock part blows most of its air directly at the nozzle height rather than on the already-printed material and is significantly offset from center with the nozzle. I've tried another fan duct replacement, the well-known vent ring, but it didn't work out for me. Concentrating the air flow through tiny openings very close to the print actually caused small details to warp just from the air pressure. So I set out to design something that gets more of the air flow across the just-printed material without focusing it. This is my first version of the fan duct that seems to work effectively. With it, I can print M8x1.25 bolt threads in PLA vertically with minimal curling/warping and 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 during very fast prints with certain designs. Initially, I tried bringing half of the air flow around the other side of the nozzle but wasn't able to make it work well. I have no background in fluid dynamics so this is all trial and error. If anyone has suggestions for adapting 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.