Dust is not our friend. It coats our tools, work surfaces, and worst of all, our lungs. Centralized dust collection systems do a good job of removing wood chips, chunks, shavings, and larger dust particles but you need something more to remove the fine airborne dust particles. That’s where an air filtration device comes in.
Most woodshop air filters hang from the ceiling, typically in an out-of-the-way corner. They circulate the air, trapping dust particles that may or may not have been generated close by. What’s different about this unit is that it’s on casters so it can be wheeled close to the action and trap most of the dust at the source before it has a chance to spread throughout the shop. It’s works particularly well when sanding or routering.
Before I built this portable air filter, there would often be a discernable dust cloud in my shop. And lots of nasty stuff in the ole nostrils. But no more. Now the air is clear and the hanky comes out clean. I’m not saying the shop is 100% dust free but it’s much cleaner than it would be without the air filter.
Materials and Construction
I made the air filter unit over the course of a weekend at a total cost of under $100. The requisite materials are:
- one sheet of 1/2″ plywood
- few scrap pieces of pine and masonite
- one attic fan
- standard light switch
- 7 foot extension cord
- metal screen with 1/4″ spacing
- furnace filters
- four casters
The plywood box contains two inner compartments: one to house the fan and one for the filters. A heavy duty piece of 1/4″ screen separates the two compartments. Screening is also used on the exterior faces to protect the filters and to keep fingers and other body parts safely away from the fan blades. The electrical switch and wiring is out of the way in the fan compartment.
The filter compartment holds up to four 20″ x 20″ conventional furnace filters although I typically only use two filters. I probably need finer filters because a layer of dust has gradually accumulated on the fan motor. (Or maybe just change the filters more often). The filters slide into slots formed by 1/4″ pieces of masonite sandwiched between 1″ wide pieces of pine. A cap piece with holes drilled partway into it for finger holds sits on top with a rabetted piece of 1/2″ plywood on top of it. That’s pretty much all there is to it.
But there is a tradeoff…
The tradeoff with this design is that it takes up valuable floor space. My woodshop is a bit cramped and there are times when the box gets in the way. I can see where a ceiling mounted air filter makes sense. On the other hand, I like being able to suck up dust near the source before it disperses too much into the air. Also, the unit often doubles as a cart for transporting wood stock from one machine to another.
So, in spite of the occasional floor space issue, I plan to continue using this roll-around air filter unit until the fan dies (it’s been going strong for 15 years). At that point, I may replace it with a commercial ceiling mounted filtering device. Or, I may fix it and continue using it. Or, I might decide to use both a portable unit and a stationary ceiling mounted unit. Decisions, decisions …