Shop Air Filtration

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Project by rodneyh posted 03-14-2011 03:21 AM 4905 views 20 times favorited 10 comments Add to Favorites Watch

I made this air filter yesterday afternoon. Was getting tired of breathing all that sawdust. The blower is from the downdraft of a kitchen range that we replaced a few years ago. Just couldn’t throw it away. It’s 1/8 hp, so it’s at about the point of a commercial filtration system in the 600-800 cfm range. The box was made of scrap plywood I had around. The big expenses were $20 for the coarse filter and another $20 for the fine filter, so I’m in a total of 20 bucks instead of $300 or so. The coarse filter is electrotratic and washable. It’s rated at MERV 8. I used almost all of the 25×20 filter by covering the top and both ends. The fine filter is a Shopvac HEPA filter. I believe it’s rating is 95% at 1 micron and 85% at 0.3 micron. I got really lucky as it slig snugly on the inlet to my blower (6”). The whole box is about 23×14 x 13, and weighs maybe 15 – 20 lbs. I was planning on ceiling mounting it, but it’s very convenient for moving around the shop as it is.

10 comments so far

View Ryan Bruzan's profile

Ryan Bruzan

153 posts in 4234 days

#1 posted 03-14-2011 03:33 AM

Where did you get the filter material?

-- Built with FOREVER in mind.

View shimster's profile


96 posts in 4346 days

#2 posted 03-14-2011 03:47 AM

Does it work?

-- Less is More.....expensive

View rodneyh's profile


147 posts in 4004 days

#3 posted 03-14-2011 03:54 AM

HardWood – both filters from Lowes

algale – I went back and forth between something like yours (MERV 12) and mine (MERV 8 plus HEPA). When I discovered the Shopvac HEPA slipped right on my blower, I was sold.

shimster – I know it’s pulling a lot of dust from the air, as the outer filters are pretty coated after just 1 day. I think the vac companies have the HEPA thing dialed in pretty well, so it likely works as advertised. As far a CFM, I don’t know right now, but I’ll come up with a way to measure it and update my entry when I do.

View NBeener's profile


4816 posts in 4513 days

#4 posted 03-14-2011 04:16 AM

Very nice job !

For whatever reason, I just think these are great projects :-)

-- -- Neil

View Brent Livingwell's profile

Brent Livingwell

75 posts in 5097 days

#5 posted 03-14-2011 04:29 AM

Yep, you just saved my lungs as I have there seems to be a 1000 tools that i NEED before I can justify the much needed shop filter. I do have a fan just waiting for this.

Thanks, nice one.

-- Things of the greatest worth are from the Earth. If you tell yourself that something is "close enough" it is it again.

View steliart's profile


2895 posts in 4028 days

#6 posted 03-14-2011 09:20 AM

very cool project

-- Stelios L.A. Stavrinides: - I am not so rich to buy cheap tools, but... necessity is the mother of inventions !!!

View NoLongerHere's profile


893 posts in 4015 days

#7 posted 03-14-2011 02:30 PM

We were just talking about making one of these no too long ago.

I was a little pessimistic because of several issues you seem to have addressed, and I’m prejudice because I already own a Jet air filter.
Yours came out real nice. Multiple washable filters, the hepa filter fits the intake, light weight. and cheap.
BTW – 20+20=40.00 had to tease you for that one. Still cheap!

The fan looks like it was made for this application with the exhaust tube. Nice air cleaner.

Are you going to try and put in a variable spd. switch?
You could plug it in to a remote controlled outlet adaptor too.

Good project. I’m now a believer!

View rodneyh's profile


147 posts in 4004 days

#8 posted 03-14-2011 03:51 PM

reedwood – No plan for a variable speed switch. I figure when I want filtering, I want as much as I can get. The noise level is not bothersome at all, even working within about 5’ of it. As far as a remote switch goes, right now I don’t really need it as it just sits on a bench. If I permanently mount it, I’ll likely go “remote” just by wiring it up to an outlet box and a couple 3 way light switches. I won’t have a remote control (that I know I’ll lose anyway) with a timer, but I can just mount the switches in a couple convenient locations in the shop.

View Sandy's profile


249 posts in 5264 days

#9 posted 04-05-2012 08:15 AM

I just came across this project, as I have a blower motor from a furnace I replaced, so a full shop air filter is on the “to do” project list. Have you thought about using a wall mounted timer switch, like the kind used on Jacuzzis?

View neufeld15's profile


5 posts in 3307 days

#10 posted 04-29-2013 04:25 AM

I like the 2 stage filter. we have a bigger version of this at my dads shop, but it’s just a coarse filter, but it does make a huge difference. Great work!

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