Homemade air filter

Travis Porter · 02-11-2008, 11:18 PM

I was asked about my homemade air filter in another thread and I have taken a few pics to show what I did. In some instances (rare as it may seem) I will make tools/shop accessories instead of buying them. This is one of the instances where I did. I got the initial design for this I believe out of a Woodsmith or Shop Notes (can't remember which), and have done a few modifications to it. This is my 2nd iteration of air filter system. Same blower as the first, I just learned a lesson and made this one a whole lot lighter and used a more standard sized filter to make it easier to get replacements. I would NOT use 3/4" plywood to make this. It will be far too heavy and awkward to get mounted or hung from the ceiling. DAMHIKT

Basically, what I made is a box that a squirrel cage fan fits into the middle of and draws air through 2 high efficiency filters on the intake and pushes it out one high efficiency filter on the output side. I used 14x25 filters (worked for my blower) and sized the box around them. I used 1/2" sandply plywood from the borg (left overs I had on hand) and 3/4 x 3/4 stock for the frame to hold the filters in position. Along the bottom is a 1/4 groove to slide a 1/4 luan plywood bottom in and out for filter replacement. I have found I can vacuum the filters for around 1 to 2 years before needing to replace them.

Cost to make the whole thing was around $6 excluding the filters. I had to buy the pull switch and the wire nuts. I had all the lumber and screws already. The filters are not cheap, but I would not recommend buying anything less than the best 3M ones. It does make a big difference in air quality. Before I had this when I sanded I always had a cloud of dust and all of my tools and benches covered in a fine powder.. You can literally see the difference in the air, and the tools and benches being covered is all but gone.. I am not advocating not using a proper vacuum set up with sanding tools and such, but it is a whole lot better than using nothing at all and the price can't be beat.

Intake

intake filter grid, blower and dividing wall

Output side. There is a slot to hold a single filter on this side. It is just removed for this picture.

erasmussen · 02-11-2008, 11:23 PM

I love home made tools, excelent job

DaveO · 02-11-2008, 11:44 PM

Travis that awesome, it looks just like my $150 Jet filter

Where did you find the squirrel cage fan? Was that cost include in the $6???

Dave

Travis Porter · 02-11-2008, 11:47 PM

Fan was given to me, by whom I can't even remember for sure as I have had it for 10 years now. I think it was my father. If someone wants a fan like that I can probably get a couple for free. Just let me know.

mcoston2 · 02-12-2008, 05:04 AM

I find that hand made tool work just as good, if not better than store bought. Great job...

Bigdog72 · 02-12-2008, 05:23 AM

I made one similiar to yours about 9 years ago. I got the fan from an HVAC contractor who was tossing some old furnaces. Used the same filter set-up as the commercial jobs. You are definitely right about the 3/4" plywood, mine weighs a ton!

Glennbear · 02-12-2008, 08:35 AM

Very nice job, shopbuilt air filter is getting close to the top of the list of projects and now I know to downsize to 1/2" sheet goods, I had not really considered the weight of 3/4"

pcooper · 02-12-2008, 09:13 AM

I really like that filter idea, I made one similar with a box fan, but I like yours much better. Thanks for all the good pics for detail!!!

gator · 02-12-2008, 09:22 AM

Originally Posted by DaveO

Travis that awesome, it looks just like my $150 Jet filter Where did you find the squirrel cage fan? Was that cost include in the $6???

Dave

Go to any HVAC dealer in town and most will have a pile of air handlers out back. Ask and most of them will tell you to go out back at take the one you want. Thats how I got mine.

George

Jim Murphy · 02-12-2008, 10:09 AM

Originally Posted by gator

Go to any HVAC dealer in town and most will have a pile of air handlers out back. George

George, I just called 3 different HVAC folks here in Raleigh and all of them say they take their "swap-out" stuff directly to the landfill/junkyard. Who did you get yours from? I may have a road trip to Oxford in my Friday future.

gator · 02-12-2008, 10:51 AM

Originally Posted by fernhollowman

George, I just called 3 different HVAC folks here in Raleigh and all of them say they take their "swap-out" stuff directly to the landfill/junkyard. Who did you get yours from? I may have a road trip to Oxford in my Friday future.

I got mine from Oxford Heating and Cooling on College St about two blocks before hitting the loop road on the north side (3-4 blocks past the hospital). If that doesn't work I have another place I can check.

George

Douglas Robinson · 02-14-2008, 04:55 PM

FWIW:

The plans are in Woodsmith Issue No. 95.

Doug

lottathought · 02-14-2008, 07:56 PM

If this works as well as the store boughts, it is a fantastic solution.
Did the Woodsmith issue list anything about the ability to clean the air as compared to Jet...etc?
I need one of those spinny things too..
This might be just what I have been waiting for.

Dutchman · 02-14-2008, 08:20 PM

Another option to consider is washable filters. I put some wire in the opening behind the filter for support. The filter fits in a groove around the perimeter. I'm hoping I can just take it out in the driveway and wash it out when it gets too dusty. I just haven't been able to make a lot of dust lately.

mturi · 02-14-2008, 08:53 PM

Great idea Travis. Thanks for the pics. I really wanted to make one of these but did not realize the fans were that accessbile for free. I would imagine the motor sizes vary and I read somewhere that a good target is to cycle the air around 12 times per hour based on a specific shop size but I guess some filtration is still better than none.

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