Fan Duct Damper 120mm

I designed this thing for my Lack enclosure. It covers a rear mounted 120mm exhaust fan to prevent heat loss when the fan is not needed, and opens to direct hot air upward when the fan is moving. The flapper is 0.6mm thick to keep it light and responsive, which works well 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 in to the flapper. This provides a solid bond to the flapper, and allows 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 in to the main duct and enjoy.

Depending on how well your printer is setup, the flapper seat may turn out "bumpy" which doesn't provide the best seal. To improve the seal, you can apply some masking tape around the edge of the duct so it is just touching the flapper in the closed position (see second photo). Also, my printer couldn't quite print the flapper clean enough to move smoothly. If that happens, 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 it's own before you call it done.

Note that this and most other passive methods used to prevent drafts through your fan ports will create back pressure. You will want a fan capable of dealing with this. I use a "Delta Screamer" fan (model FFB0912EHE) for my enclosure exhaust (with a 120-92mm adapter). It is specially designed with stator vanes to create a lot 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 air flow to do its job well. The static pressure rating for my Delta fan is spec'd at >0.6 in. H2O. Be aware of this spec when searching for fans for higher pressure applications.

Print Settings

Rafts:

No

Supports:

Resolution:

0.3

Infill:

Notes:

Rotate the flapper 90* so the blade sits flat on the bed. Print the flapper separate without supports. The flapper is thin so be patient and let the bed cool off before prying it up.

Print the main duct with supports everywhere. I used 35% supports, zigzag, with a min angle of 45degrees.

If you plan to use it on a printer enclosure or similar hot environment, print it with a high temp plastic like PETG or ABS. The extra stiffness of PETG helps the thin flapper keep its shape.

Category: 3D Printer Accessories