# Shop Built Air Filtration



## jg2259 (Oct 28, 2011)

I know there have been many discussions on the need and performance of air cleaner/purifiers. However, I believe that it will help clean the air in my shop. 
My plan is to build my unit using a squirrel cage fan from a Jenn-Air kitchen fan, installed in a 16"x16"x20" box. I plan is to us 2 layers of 1" semi quality pre-filters which will slide into dados in the box. 
My question is, what do you all think about instead of using an expensive hepa filter as my final filter, to rig up a bracket on the end of the squirrel cate fan? I would then use a piece of all-thread screwed into the bracket and install a shop vac type hepa filter onto the all-thread, thus reducing my cost of expensive 16"x20" hepa filter, to just the (still costly) shop vac type hepa filter?
Thanks for any and all opinions. 
Jim


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## ryan50hrl (Jun 30, 2012)

Check out my build. 

I also used a 600 Cfm fan out of a kitchenaid hood...and am using 20x20 furnace filters slid into dado like structure. 

My first filter is a 2 dollar filter....the second filter Is a 5 dollar filter...and the final filter is a 20 dollar high end furnace filter. I change the first stage every month or so...the second stage is still original....but probably getting close to needing replacement. The final stage is as white as the day I put it in....


I placed clear packing tape over the output and ran the filter for a few hours while sanding and the output had virtually zero dust in it.....

Total cost for filters...under 30 bucks 


http://www.woodworkingtalk.com/f32/home-made-air-filter-45667/

And very cheap maintenance on the first filter.


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## Dave Paine (May 30, 2012)

I am not sure about pressure drop of the shop vac size filter vs a full size filter.

I happen to have a used Goretex shop vac filter which was in a Rigid shop vac which finally failed due to the bearings wearing out. I threw out the shop vac but kept the filter. Does not fit my Fein shop vacs.

Happy to send it on for the cost of postage. Should not be much to get across the state. Send me PM with your address if interested.


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## tvman44 (Dec 8, 2011)

I use a single 20" x 20" filter on my box fan but want to add a second filter as mentioned. A cheap pre-filter and a better 2nd filter. I think 3 filters would be too much on a box fan, 2 may be too much I will have to try it.


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## Fred Hargis (Apr 28, 2012)

ryan50hrl said:


> My first filter is a 2 dollar filter....the second filter Is a 5 dollar filter...and the final filter is a 20 dollar high end furnace filter. I change the first stage every month or so...the second stage is still original....but probably getting close to needing replacement. The final stage is as white as the day I put it in....
> 
> 
> 
> ...



This was the way I built mine as well, I think I did finally have to replace the 3rd filter, but it was only after several years. The first one got replaced about every 3 months or less, if i was doing a lot of work in the shop.


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## TMA Woodworks (Apr 23, 2010)

Hi Jim

I used a squirrel cage from an old furnace for mine. The filters I use are just a high grade furnace filter. Most of the ones I have looked at take particles as small as one micron. You can put a hepa filter on but don't think that you need to spend the money on it. My filter clears the shop in less than 5 minutes and will even take the burnt wood odor out.


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## jg2259 (Oct 28, 2011)

Thanks for all of the replies. I am going to follow your build ryan. 
And thanks for your offer Dave, I'll let you know if I decide to go that route.
I hope to get started on it tomorrow morning, doing a little work each morning because I'm on afternoon turn this week.
Thanks again everybody.
Jim


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## ryan50hrl (Jun 30, 2012)

One thing I'd change....I made a dado for 1/4 inch plywood to slide in for the top....I'd now use a thicker piece hinged from the back with weatherstripping to seal it down.


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## ryan50hrl (Jun 30, 2012)

Oh, and I also ducted the fan through the wall into the next room with 8 inch round vent I keep the air from kicking more dust up.


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## ChipperOfWood (Oct 18, 2012)

*My home made shop air filter*

Here is a link to my shop made air filter. http://www.woodworkingtalk.com/members/chipperofwood-33888/albums/air-cleaner/
It is built to hold 3 1" filters in front of the fan however I only put 2 filters in front of the fan and 1 good filter at the outlet. The first filter I change out every couple of weeks or less depending on what I am doing down there. The fan is a squirrel cage salvaged from a furnace that I got from a neighbor who is a HVAC contractor.
Seems to work very good.:thumbsup:

Charlie


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## TMA Woodworks (Apr 23, 2010)

ChipperOfWood said:


> Here is a link to my shop made air filter. http://www.woodworkingtalk.com/members/chipperofwood-33888/albums/air-cleaner/
> It is built to hold 3 1" filters in front of the fan however I only put 2 filters in front of the fan and 1 good filter at the outlet. The first filter I change out every couple of weeks or less depending on what I am doing down there. The fan is a squirrel cage salvaged from a furnace that I got from a neighbor who is a HVAC contractor.
> Seems to work very good.:thumbsup:
> 
> Charlie


Charlie
Yours looks a lot like the my first one. It did really well except it took 15 guys and a keg of beer to get it hung from the ceiling. :yes: This time I made the box the same size as the squirrel cage and put the filters right next to the intake on the bottom. I made the frame from 2x2's and then use hardboard as the skin. It took a ton off the overall weight.


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## ChipperOfWood (Oct 18, 2012)

TMA Woodworks said:


> Charlie
> Yours looks a lot like the my first one. It did really well except it took 15 guys and a keg of beer to get it hung from the ceiling. :yes: This time I made the box the same size as the squirrel cage and put the filters right next to the intake on the bottom. I made the frame from 2x2's and then use hardboard as the skin. It took a ton off the overall weight.


That does look a bunch lighter. I used what I had around the shop. The skin is 1/2" plywood. Actually I put mine up where it is by myself. I have a shop cart that is on casters and a couple of large wooden boxes that I have plus some 2x4 and lifting one end at a time I gotter done. Then I had the beer. :yes::laughing:


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