Fan Duct Damper 120mm

thingiverse

I designed this thing specifically for my Lack enclosure. It covers a rear mounted 120mm exhaust fan, preventing heat loss when the fan isn't needed, and opens to direct hot air upward when it's moving. The flapper is 0.6mm thick, keeping it light and responsive, which works perfectly with PWM+PID controls. The hinge holes for this thing are designed for 1mm wire. After printing, heat your hinge pin wires and push them into the flapper, providing a solid bond to the flapper and allowing some flexibility in wire diameter. If you use bigger pins, drill out the main housing notches to allow smooth operation. When the pins are set, snap them into the main duct and enjoy. Depending on how well your printer is set up, the flapper seat may turn out "bumpy," which doesn't provide the best seal. To improve the seal, apply some masking tape around the edge of the duct so it's just touching the flapper in the closed position (see second photo). Also, if your printer can't quite print the flapper clean enough to move smoothly, sand down the back and top sides of the flapper hinge barrel as well as the round edge of the flapper until you get smooth operation. The pics show the flapper with my fan on and off; make sure it opens up smoothly and closes completely on its own before calling it done. Note that this and most other passive methods used to prevent drafts through your fan ports will create back pressure. You'll want a fan capable of dealing with this. I use a "Delta Screamer" fan (model FFB0912EHE) for my enclosure exhaust, along with a 120-92mm adapter. It's specially designed with stator vanes to create more pressure than your typical cooling fan. It pulls air through my 120mm fine mesh intake filter (cotton T-shirt material), my louver damper intake, and this exhaust damper while still having plenty of airflow to do its job well. The static pressure rating for my Delta fan is specified at >0.6 in. H2O. Be aware of this spec when searching for fans for higher pressure applications.