Instructables
History: First off, a little history of how this project got started. I use 20X20 box fans. I have one in the window and every couple months, I have to pull it down and clean the fan and the screen that is on the window. This would be a good project for me to work on.
To use the box fan and a 20x20 filter, I wanted to make it easy to change and with little or no cost.

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Step 1: Checking out the bottom bracket.

Picture of Checking out the bottom bracket.
Step #1.This step you will see the pictures on the metal that I used to make the brackets that I needed to hold the filter and the fan. I going to start with the bottom bracket. It is made of channel that is 1/4x1/4x3/4 medal. The brackets are 2 1/2 inches long. On this part, I drilled two holes. One the same size of the screw that I took out and the other one big enough to get my screw driver in to put the screw in. There is one bracket on each side. These brackets hold the bottom of the filter.

Here I show the picture DSCF0122.

Step 2: Checking out top bracket.

Picture of Checking out top bracket.
Step #2 This is the top bracket. As you can see by the picture the bracket is upside down. The flat side is down. Also I had to drill a few more holes in this one. These holes are all the same size. Big enough for the screws to go through. As you can see by the picture, this is a much longer screw. It goes through all three holes plus the fan. I used self starting screws so I put this one in with my screw gun. It needs to be loose enough so that the outside medal part will spin. That part is also 2 1/2 inches long. It is 3/4 wide.

Here I show the picture DSCF121
awilson692 days ago

Wow its an cool solution for indoor air pollution. One of my friend also made an awesome product like this name Fan Buddie. Its an air purifier. Its a very unique product. I am using it. I bought it from https://www.fanbuddie.com/

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I'm going to try this with bolts in the frame and fender washers to hold the filter on! Thank you for the post!

brandon05w3 months ago
I've been doing this for years and it works great!
Try drilling hole in one end of channel close to the edge. One small for screw one large for screwdriver to get to screw. Place channel turned over so that it faces down. I useda machine screw with lock nut through the existing hole. channel pivots down to hold filter. had to take off guard on other side to get nut on screws.
cateddy (author)  pgnelson1081 year ago
Thanks for looking at my instructable. It really works good for us. It only takes a couple seconds to change the filters. We use one in the window to catch the dust. We have 3 set up so we can use the other two where we think that we may need them. I put one in the shed and took my blower and started blowing the dust around so that the filter could catch the dust. Well thanks again for the comment. Chuck
mccool2 years ago
Is it possible to reduce the speed of these fans?
cateddy (author)  mccool2 years ago
Thanks for the comment. The fans have a speed control on them. Either 2 or 3 speeds. Not sure. Probably if you wanted you could put a variable controler on one.
Xyzo3 years ago
By the way, cateddy's design is really nice. I'm just too lazy so I used blue tapes.

These 20" box fan are just awesome!
cateddy (author)  Xyzo3 years ago
Again Xyzo. Thanks for those comments.
Xyzo3 years ago
Easier way: tape the filter to the fan box with some blue tapes.
Better filter: 3M filtrete 1500, worked great w/o extra noise. (3M filtrete1000 cheaper alter.)
Longer filter life: add extra fiberglass pre-filter(s) before 3Ms.
Better Fan: Fan w/ remote, or add a remote on/off switch to your existing one

Put these around home, and saved.
No more expensive HEPA filters/air purifier needed. :D


cateddy (author)  Xyzo3 years ago
Thanks for the comment Xyzo. The filters that I use cost 69 cents each. I don't think that you can beat that price. For what I am using them for, they work really well. The last box of filters that I bought, I just had Home Depot order me a box. They didn't charge me shipping and they gave me a 10% discount. One thing for sure, the filters sure helps keeping the fan clean. Thanks again for the comment and for checking out my project. Chuck
dittyjunk4 years ago
The problem with this box fan is the airflow is not even.  Which caused the suction not pull evenly,  minimize the filtering process.  I made one the same concept except, instead of directly attach filter to the fan.  I build a box out of construction foam about 5in deep to create a air volume which caused the air suction to be more even.  I get a full evenly distribute dirt on the filter.  Optimize the performance of the air box fan.
cateddy (author)  dittyjunk4 years ago
http://www.instructables.com/id/Intro_The_fan_the_filter_together_again/

This is the first one that I made and I think that it would be more to your liking. It has 2 filters, one on each side. I don't have pictures of it. I gave it away when I moved away in around 2005. I used it at work for different things. For paint and also for the dust. This filter would do what you were talking about. Cover the whole filter. I had a big fan motor on it with lots of horses power. Sorry about not answer you comment earlier. I don't check this email too often. Thanks for the comment. Chuck
buenafe4 years ago
Clever. This makes me want to go out and buy a box fan.
cateddy (author)  buenafe4 years ago
Hello Buenafe. Sorry about not replying to your comment. This went in my spam box. I use 2 of these fans just about everyday. One is in the window and the other I set in the hallway. Here in California is like living in a dust bowl.
cateddy (author) 5 years ago
Thanks for the comment. Check back I have another one that I am working on for paint. I took that first picture that I made in paint and redoing it. I am putting a dryer pipe on it to where you can run the stuff out side just like the dryer do.
foobear5 years ago
cool! I've been wanting to get one of these from dick blick for around $300 bucks for ventilating paint thinner odors and such.