Air filter exhaust adapter to attach 8 inch/200mm hose

I wanted to be able to redirect the exhaust from my air filter to an 8 inch/200mm diameter outside vent, so I designed this adapter. It can be attached directly to the air filter using the screws which hold the grille in place. 

My filter is made by King, but there are several other models which seem to have an identical exhaust design (for example Wen). When in doubt, measure the dimensions and test the size by printing just the first few layers (like I've shown in one of the photos).

Assembling

You'll need to open the back of your airfilter to install the adapter. I obviously don't take any responsibility for any damage to yourself or your filter you may incur when doing so, but it's quite straight-forward as shown in the photos: Unscrew the screws all around the back plate, then unscrew the 6 screws holding the fan to the rectangular exhaust. Be careful with the wires, you don't want to rip or cut any.  Attach the adapter (with or with out the metal grille) using the same screws, then reassemble the back.

Printing

The model just barely fits on my Prusa Mk3 print bed, with deactivating the skirt - as preconfigured in the included 3mf file. In this orientation, no supports should be needed. Depending on your printer, you may have to do some adjustments yourself.

Exhaust outside vs recirculation

I'm using the magnetic connectors designed by SKT to quickly change the exhaust from recirculation (in winter) to an outside vent (in summer), see some of the later photos. I also designed a cap to close off the vent in winter, in case that might be of interest to you.

Design files

The Fusion 360 file is attached, in case you want/need to adjust it to your own needs. Note that the model actually also includes the design for a splitter with blast gates - which I abandoned when I realized it would be way too big for my printer, and that using the magnetic hose adapters by SKT would be way easier and convenient.  But maybe you'll find the design useful yourself. (Just be aware that I've never actually printed or tested the splitter.)