Wednesday, July 5, 2017

Shop Cart Air Cleaner v1.5

A few months back, I made an ambient air cleaner out of a shop parts cart. I enclosed the lower tier of the cart with furnace filters and installed a 25" box fan on one side to draw air through the filters and out the fan. Hopefully this would help to clean some of the fine dust out of the air in my workshop, where I do a lot of woodworking.

After using this cart for several months, I can say that it definitely removed some dust from the air. About once a week I would see sawdust building up on the outer layer of filter material, and I would clean it off with the shop-vac. And recently I took the fan out to do an upgrade, and got to see the inner filters, and they are definitely dirty too.

Although it does a fair job of pulling dust out of the air, my shop is large enough that the air cart could definitely do a better job if it could move more air faster. That means an upgrade to the fan. It just so happens that hiding up in the shop's attic I found two furnace blower fans with motors. One of them is going to get mounted to the wall and serve to vent the air out of the shop through the back wall, which will give me some much needed ventilation in the summer. The other is narrow enough, and just about the right height to be mounted in the side panel of the shop cart air cleaner.

After doing a quick cleaning and cursory inspection, I gave all the bearings a quick spurt of lube. Then I wired the motor up for a test spin. Once I was satisfied that all was in working order, I took measurements to see how well this unit might fit into the shop cart air cleaner. The answer was- "like a glove!" I would be hard pressed to have made a flange for this blower that would have fit the cart better.

Next came some wiring. I decided to install a two-gang box on the face of the flange. One side would have a 15 amp light switch for turning the fan motor on and off. The other side would have an always on electrical outlet. The box is fed from a heavy duty three wire cord with a plug end, that I salvaged from one of the ceiling light fixtures (which plug into electrical outlets mounted in the ceiling) when I made some changes to how those cords were routed.

I hadn't really planned on completing the cart upgrade right then. I was really just checking out the blowers and their suitability for the task, but everything went together so smoothly, the next thing I knew, I was half way finished and so I said "fuck it" and wend ahead and installed it.

I had to remove the box fan from the wide side, and the filter panels from one of the narrow sides, and install the blower flange to be flush with the narrow side of the cart. In order to keep it stationary, I drilled two small holes down through the top of the cart into the top of the flange and put sheet metal screws in them. I had to make two tiny wood blocks to screw onto the tips of the screws to keep anyone from getting jabbed by them.

The first time I built this cart, I used masking tape to seal up the gaps, and that worked OK, but this time I decided to try something more substantial. I used aluminum furnace tape- and it worked swimmingly.

The blower has an open front, which could potentially get things falling or shoved inside it, like tools, or hands, so I needed to cover it for safety sake. I had some left over hardware cloth from a recent renovation project. I cut a piece out that was big enough to cover the opening in the blower flange. Then I folded over the edges with a metal ruler so they would not be sharp. I was going to add a piece of that cheap fiberglass filter material to the cover also, but I decided it wasn't really necessary, and might restrict airflow. I

I secured the vent cover to the blower flange with more sheet metal screws.

That's really about all there was to this upgrade. Install a new 25x25x2" filter where the box fan was and we are good to go! Not only do I now have a more powerful air cleaner, but it also features a movable electrical outlet for tools. I just have to keep in mind that the blower motor pulls a lot more amps than a box fan, and not overload that circuit by plugging in too big of a tool while the blower is running.

See Also:
Shop Cart Air Cleaner



  1. You can even wire stuff like that? damn... Now I am really jealous.
    For me electricity is a bit like magic... Some people can do it others don't.

  2. This kind of wiring is super simple. I wish i could do the kind of wiring done by people who make things with arduinos and raspberry pies and such. That is like magic to me. I would love to incorporate some of that kind of thing into my prop builds.

  3. Everything that sends electric pixies through cables scares the crap outta me, no matter how simple. My wife even has to change lightbulbs herself...
    Arduinos and raspberry pies...
    Now that's high magic ;-)