The ubiquitious K40 laser cutter / engraver typically either includes an in-built exhaust blower / fan or includes one as an accessory. Many people upgrade the exhaust blower / fan as well. Mine also included a section of 4" dryer duct and a (single) hose clamp. That works for connecting to the laser, but I needed to be able to connect the other end somwhere (preferrably somewhere that vents outside).

I wanted something that I could setup permanently or semi-permanently, so I wanted it to be durable, secure, and seal well. The typical solutions available for air conditioners and such are none of those things, so I decided to build my own. I sawed, routed, and holesawed a scrap of dimensional lumber to fit in the window and then primed and painted it. Next I needed a way to connect the exhaust hose.

I wanted something that would:

• be securely mounted
• seal well
• minimize restriction of egress flow
• minimize ingress flow due to wind
• prevent intrusion of insects

There are five pieces to the completed assembly, though the screens and frames can be omitted if desired. After printing and post-processing, I cut appropriately sized screens and used a CA Gel (Loctite specifically) to glue the screens in place. I did this in stages to allow the bottom to dry before gluing the remaining edges to be able to pull the screen tight (ish) before gluing the remaining edges. I then glued in frames, and filled in small gaps with CA glue. After a day to cure, I sanded everything smooth.

I had used a 3-3/4" holesaw to cut a hole in the board, so only had to pre-drill the holes for the flange and then install the exhaust port using eight #6 x 1" round head wood screws. Installation was completed by connecting the dryer hose to the exhaust port and securing it using an additional hose clamp from the local big box home improvement store.

I have included the .stl files for the exhaust port and the screen frames, as well as the .skp file including both models.