Air intake for air cleaner. I used half-lap joints to build the frame (20.75”x20.75”)
All the sides are cut, as well as the rabbets and dados according to the plans I drew. (Page 1, Page 2, Page 3, Page 4) The motor was put inside to take a few measurements for where to cut the air outflow. It is upside down in the picture, however.
I mounted the squirrel motor to the inside wall with 1.5” wide pieces of 3/4” plywood. Some of the screws were drilled through the sheet metal tabs and others to the side alone.
The sides were attached to the top and bottom with 2” sheet rock screws, they are spaced approximately 3” apart. I also cut a hole for the gang box to house the rocker switches for the various fan speeds. I also attached t-hinges to the area where the filters will be for easy access. I chose that style of hinge because it was the only ones I had on hand that would work.
View of the air intake area. I will be installing guides to hold the filters in place. I should also mention that I added 5/16” metal hoops to the top so that it can be suspended from the ceiling – washers on each side with a bolt on the inside.
-- Fr. Thomas, http://www.monkwerks.org