This project must be dedicated to my Dad, and you’ll see why. Here it is:

What you see is a carbon air filter made out of a Dollar Store “crate” (about 8″ x 7″ x 6″). It’s used to pull soldering fumes aware from the builder, clean out some of the gunk, and exhaust cleaner air. The black part is the carbon filter.

Here’s a view with the filter taken off. Those of the Nelson Clan will understand why this is dedicated to my Dad:

Fans! My Dad loves fans, and this has four of them. The above shot is kinda cool, because you can see them spinning (a full-sized photo is in the gallery).

The unit is designed to suck air in through the front (through the filter), then it goes through the fans, and is exhausted out the back and the sides. I used pieces of foamboard, cut to fit tightly, to make a 2″ space between the fans and the filter. This helps prevent the fans from getting ”bogged down” and acts as a baffle.

Here’s a photo of the switch. It’s nice when you have a round switch that fits perfectly into your dollar store crate:

In the above photo, you can see the exhaust holes on the side (all four sides). There are also holes in the back. This allows you to operate the unit on any side, or sitting upright, depending on your needs.

The power supply is a left-over unit from a dead external hard drive (thanks, Mike). It give 12V @ 3A. You need a LOT of power to drive fans. My bench supply started getting sad at the 8 fan count.

I designed the unit to support 8 fans total, four toward the rear, and four up front (right behind the filter). So far, I’ve only done the rear four fans, because I want to see if the other four are necessary. We tested the draw with some incense and it was sucking fumes from over 18″ away. Not bad!

Why so many fans? Well, I was originally going to do this project with one nice fan. But the filter is tough on the guys. If you put the filter too close, it bogs down the fan. So, I decided to beat the problem with quantity, and ordered a bunch (10) of 80mm fans from Goldmine Electronics. They were dirt cheap ($1.60) each–in fact, those 4 fans cost less than the one nice ball bearing one I was previously testing with. More fans mean more surface area. From my experiments, it seems to give a nice draw, doesn’t kill the fans, and has a good (6″ x 8″) filter surface area.

The baffle & spacing between the fans and the filter is important. The space seems to help the fans intake better, and they don’t sound anywhere near as labored as when the filter is closer. The filter sits about 2 ” from the fans. For the filter material, I bought a package of carbon filter from Lowes. It was about $12 and is a big 16″ x 48″ piece, so I’ll have filters for a while.

In total, the cost was: $1 crate, $8 fans, $1 foamboard, $0 recycled power supply & jack, plus $2 for filter (cut up). That’s $10 for the unit and <$2 for filters. Given that new units start in the $50 range, that’s not too bad.

It won’t filter out nasty crap, but it will at least clean up those solder fumes. And it’s small enough to fit on a desk. I was going to make this hose-based, with the unit on the floor, but this came out nice, so we’re leaving it on the workbench.