The K40 laser is shipped with a wimpy underpowered exhaust system. It is one of the first upgrades one needs to address if this unit is going to be anywhere near any living space. Laser cutting does stink!
I went to Rockler Woodworking in Tukwila and browsed their fittings and plumbing for woodworking equipment like jointers and planers. The K40 ships with a fan housing that accepts a 4" diameter hose. After checking other blogs and such I decided to stay with the 4" standard as much as possible. I found the above 4" dust extraction fitting. The outside dimensions are 8" x 8".
Next, I measured out the fittings on the back of the laser and created an "adapter" to connect the the hose fitting to the laser. I used Baltic 9mm birch plywood
Lining the parts up to make sure it is the correct size.
Here's the unit put together.
Here's another shot. Next up: A new fan to attach to it.