Designing a Corsi-Rosenthal air filter box for my garage workshop

It’s been over a year since I last wrote about building an air filter for my garage workshop, but I’m finally making progress toward designing and building my own Corsi–Rosenthal Box. I recently received a nice miter saw and decided to try my hand design and building with US dimensional lumber, since its relatively ubiquitous and comparably cheap.

Rendering of workshop air filter showing just the nearly-cubic wooden frame

Using some inexpensive 2x4s, 3-inch #9 screws, and some leftover MDF or plywood (haven’t decided yet), I’m planning to build a box that supports the same HVAC filters I use in my home. That way, I can buy the filters in bulk and use them in multiple places.

While I don’t love working in US customary units, I’m designing for the materials I can access, so everything’s in inches! 🥴 This design is intended to work with a very nice exhaust fan with a sealed motor.

Technical drawing of top plate with a 16-inch hole for the fan and markings for screw placement

Technical drawing of the sides showing the arrangement of the 2x4 blocks and markings for screw placement

Technical drawing of multiple views of the assembly with indications of the four unique lengths of 2x4 blocks needed

I’m looking forward to executing on this plan!