Homemade Dust Collector Submission

A GRM reader, Ben Bowman, just sent this in an email, so I figured it was worth sharing with everyone. I'm not sure something like this would actually protect against paint fumes, but it should do well with dust.

Here is my homemade dust collector. My first one was made out of a 4' by 8' sheet of 1/2" plywood. My furnace guy made up this metal version in exchange for a stationery package. (long story, another day) But the jist is to build a box that holds at least 6 or so 16" X 20" furnace filters. In the bottom of the box mount a 120 V 12 to 15 Amp furnace motor/squirrel cage fan unit. I got mine for free from my furnace guy. A little scrounging around, you'll find one. At last resort buy a new one from Grainger for $125- +. This unit blows 120 cubic feet per minute. It's designed to be placed in a furnace supplying hot air to a 1,200 sq. ft. house. So the dust collector inhales from the top front, and exhales down to the bottom left. This creates a whirlpool in whatever space. It's on castors so it can be rolled around. I also added an on/off switch and electric receptacles for sanders, lights etc. It's been used everyday for the last 35 years. It inhales and collects saw dust, spray paint, glue fumes, drywall dust, you name it. Doesn't have to be 4' high, could be 2 1/2'. I airbrush all the time. I've painted cars. I helped a friend repaint the bottom of his 38 ft. sailboat with a two part epoxy paint. Not one dust particle in the storage warehouse. Just taped plastic around the boat, taped to the floor and worked inside a tent.

To me every shop should have one. It's a matter of life or lung cancer. 

Best, Ben Bowman

Curious...

How do you empty it without a bag?  Do you just beat out the filters in a cloud?

And why 6 filters?  Unless they change micron size, anything that can get through the first filter can get through all 6. 

I’m also wondering about the sanity of a blower fan motor that is not explosion proof parked in an airstream that includes flammables. 

I like the idea (and use similar commercial versions all the time). Just think it might need a little refining. 

Okay, I know this was resurrected by a likely paddler, but my brother and I put together some air scrubbers last year and what we learned might be relevant to the discussion.  I built us 4 of these:

It's a fairly basic metal frame that I wrapped in roofing flashing:

A squirrel cage blower would have been a better option, but time was of the essence and all we could get in short order were some regular blade fans.  In the front, we put three filters in place:  it starts with a MERV 6 or 7 - a basic cheap furnace filter - then has a MERV 13 filter behind that, and finally before the fan, there's a MERV 16 filter.  Going through multiple filters doesn't really clean any better than a single filter - it's absolutely true that if a particle can get through one filter, it'll get through all of them - but the tighter the filter the higher the cost, so the cheaper filters are only there to keep the "big stuff" from shortening the life of the MERV 16. 

We built them to provide scrubbed air for our Family Pandemic Thanksgiving Dinner last year but they work really well to cut down woodworking dust, welding smoke, and they do a fabulous job pulling cigar smoke stink out of the air.  Based on the size of the shop and the measured CFM of the fans (spoiler alert: the Chinesium fans on Amazon don't actually push as many CFMs as the rating says they do!), the math says we're filtering the air more than what they say an operating theater should be doing.  Using a air quality monitor we were able to measure a marked decrease in pretty much all the Bad Stuff in the air with these things going.

We've found that cleaning up the shop is pretty easy when you turn on the filters and just start blowing off surfaces with compressed air.  Most of that stuff gets caught up in the first filter and those are cheap to replace.