Fume extractor housing (fits skywalker roaster exhaust tube)

This is a generic fume extractor housing but I used it to connect my Skywalker roaster exhaust tube. It fits a 120x120 fan. You can also fit a HEPA filter or a carbon filter if you want to use it as an indoor fume/smoke filter device.

For my use as a coffee roaster smoke extractor if you want to protect the fan against chaff you can fit a 120x120 metallic mesh filter , but thos requires you to remove the mounting screws and clean the mesh from time to time. I personally just don't care much about that and preferred to not install that mesh, even if I have one, and did not notice much chaff when I inspected the fan. Most chaff is at the outlet of the machine and remains in the machine's chaff tray.

As a wall adapter, you can only print the fan housing and the tube adapter and just connect the fan directly to a power source. If you want the full design, you can also print the electric box, use a switch and a barrel jack socket and make the connections there. In that case you will also need to print the lid and attach it using 4 small screws. The electric box can be glued with super glue to the housing. 

I am using a 120x120mm 12V 450mA fan controlled using a variable power source. You can just connect it to a 1A 12V source or you can buy a variable fan source like I did from AliExpress. Having the speed control is a nice bonus. 

To attach the housing to the wooden wall I used 4 wood screws that go through the fan holes as in the picture.

If you use it as a standalone indoor unit, you can use 4 M4/M5 screws and 4 nuts on the other side. Those screws can go through all filters to keep them on the inside. As a standalone unit you will also need to print the provided plastic guard grill or a metallic guard like in the pictures. This protects your hands or anything  entering the fan blades. 

The tube adapter is parametric and can be customized with openscad. It currently fits a 69mm outer diameter tube like the one that comes with the Skywalker roaster..

Print it with a heat resistant material. Do not use PLA. I used PETG and it works, but it would be much safer to use ASA/ABS or PC, PET-CF. There is also Filamentum NonOilen that prints like PLA but honestly It is hard to make it stick and not warp. Also you can try HT PLA or annealing PLA but annealing creates issues with dimensional accuracy and that is needed to fit your components.