Air filter

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Project by PirateOfCatan posted 06-04-2009 12:15 AM 3233 views 17 times favorited 13 comments Add to Favorites Watch

The majority of the unit is built out of 3/4 birch plywood with poplar “trim” and doors. The fan is plugged into a switched outlet on the interior of the unit. The decora switch is located on the bottom center, within easy reach with a push stick. I put felt insulation around each of the filters, the fan exhaust port and the hole for the romex. The filters are tilted at a 32.5 degree angle to reduce the height of the unit (by a bit) and help with air intake. Lowes started to carry 10×20 filters (merv 6) which also helped keep down the size.

The squirrel cage blower only moves 180 CFM (cubic feet per minute). The basement is 22’ by 22’ and is just over 8’ to the floor boards which puts the “full clean” at about 20 minutes. A laundry room is going to be carved out in the corner (sealed as best as we can), taking out about 450 cubic feet. Plus the main work area in located around the filter, so most of the dust will be right near the filter. My hope is that is will clear the air in more like 10 minutes. I did have it on while I was sweeping up and the pre-filter was visibly dirty. We will see.

I have not done anything to finish it yet. Not sure if I will stain or just poly it. I am more than happy to put it to a vote.

-- P.O.C.

13 comments so far

View glassyeyes's profile


137 posts in 4391 days

#1 posted 06-04-2009 12:56 AM

Nice! I like your use of the space between the rafters. I vote for poly, but I’m lazy about some things!

-- Now, where did I put those bandaids?

View Christopher's profile


576 posts in 4982 days

#2 posted 06-04-2009 02:36 AM

I need to build one of these. I especially appreciate your use of exacting mathematics to figure your collectors capabilities. I am always crunching numbers in my head, sometimes to a fault.

View treeman's profile


208 posts in 4511 days

#3 posted 06-04-2009 03:13 AM

Nice job. I have also built my own air cleaner and use it every time I go into the shop.

It’s nice to know you can build your own equal or better than what you can buy.

View Karson's profile


35271 posts in 5462 days

#4 posted 06-04-2009 03:18 AM

Nice looking setup.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Appomattox Virginia [email protected]

View a1Jim's profile


118161 posts in 4639 days

#5 posted 06-04-2009 05:13 AM

View Bullet's profile


150 posts in 4391 days

#6 posted 06-04-2009 02:59 PM

Looks really nice! I, too, like your use of the space between the joists – very clever. You may want to seal the joints with some caulk on the inside to make sure all the “dirty” air goes through the filters and not through cracks.

-- Anything is possible when you have no idea what you're talking about.

View Splinterman's profile


23074 posts in 4423 days

#7 posted 06-04-2009 03:09 PM

That will really help with the fine dust…...good job.

View David65's profile


190 posts in 4347 days

#8 posted 06-04-2009 05:11 PM

Now that’s using your head AKA head room. I have been trying t build one but I am having a hard time finding an inexpensive fan set up. What I have seen cost about as much as a new set up any advice?.

-- David '65

View Bullet's profile


150 posts in 4391 days

#9 posted 06-04-2009 07:39 PM

David, (Sorry, Pirate, to clutter up your thread),
I recently built a filter similar to this (in my projects if you’re interested) and used a blower from an clothes dryer I got for FREE at my local appliance outlet. He had a big pile of scrap appliances that he had removed and let me use my tools to pull whatever I wanted. Clothes dryer blowers move about 300-400cfm so they are good for a small shop like The Pirates. Happy hunting.

-- Anything is possible when you have no idea what you're talking about.

View PirateOfCatan's profile


57 posts in 4461 days

#10 posted 06-04-2009 10:43 PM

Another source for free blowers would be heating contractors. They really don’t want the old furnaces they pull out and usually call a scrap metal person to come haul them away. Call around and I bet someone would be more than happy to let you pull one for yourself.

I mostly decided to purchase mine (for about $80) since it came with a 4” intake port. The hope being that 180 CFM would work for the air filter. Plan B being the blower gets re-purposed to dust collection around the mitre and (future) radial arm saws. Since I would be purchasing/making a smaller dust collector the small blower would act as an inline booster. Plus I wanted the longest possible life in the blower so I don’t have to rebuild it anytime soon.

-- P.O.C.

View SCOTSMAN's profile


5849 posts in 4647 days

#11 posted 06-04-2009 11:04 PM

Very well done I like this idea again back to my question again whay pay big money for these when you can make exactly the same thing yourself. I built my own a few years ago with double fans similar to yours it does a great job of clearing the dusty air from the shop I was given two very nice squirell cage fans and intend to build another one these fans are abit bigger and I will have it over the other side of the room.Alistair

-- excuse my typing as I have a form of parkinsons disease

View duasbata's profile


18 posts in 4310 days

#12 posted 07-11-2009 10:36 AM

Well designed. Where did you purchase your $80 blower from? Thanks.

View 76winger's profile


151 posts in 4179 days

#13 posted 12-28-2009 12:06 AM

Nice, I need to get something like that built for my own shop

-- Dave, See some of my creations at:

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