175 mm fan and 180mm Duct for retrofitting window fans.

thingiverse

I experienced a problem with my window fan's performance. If you want efficient air transfer from inside your house to outside, consider using a ducted fan design. Rounded fans in an open environment are good for general air circulation, but squared-off blades with a duct significantly improve airflow in apartments. Firstly, check if you need clockwise or counterclockwise fan blades. Changing the fan's direction by mirroring it on the build plate is acceptable, but turning it around on the shaft will not achieve the same effect. This design can be challenging to print due to thin trailing edges and the need for sufficient layer overlap to ensure connection between each layer. Support structures are essential during printing. A customized version of a fan model from Thingiverse (https://www.thingiverse.com/thing:2536887) is used here. This model was created using Customizer! (https://www.thingiverse.com/apps/customizer/run?thing_id=2536887). I've included an STL file where the hub has been hollowed out to facilitate fan tightening with a zip tie. It's recommended to place the zip tie on first, then secure it slightly before placing the fan on the hub.