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Air Filtration Unit

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Project by RoadHogg posted 04-13-2014 03:57 PM 2301 views 4 times favorited 11 comments Add to Favorites Watch

Setting up shop, I wanted something that would filter dust from the air. This is of course a supplement to a face mask and dust collector. As many others have done, I started with an old furnace fan and motor. I just built a box from 3/4” Birch plywood, made a Douglas Fir frame for the far to sit on and enclosed it all. I installed a switch and cord for convenience. Initially I had three filters in series but that proved to be far too restrictive and I was getting very poor air flow. Also, the whole unit ended up being just a huge “in the way” box that was hard to move around. I reworked the filters so there are now three filters in parallel and I put some wheels and adjustable feet on the box, installed a top and a cleat system so it will now serve as a work table and outfeed support for the table saw.

-- "The difference between school and real life is that in real life the tests come first, and then the lessons" -- Robert Lang, ReadWatchDo.com





11 comments so far

View SteveW's profile

SteveW

392 posts in 2319 days


#1 posted 04-13-2014 04:31 PM

Great job and the nice thing is, it does double duty as an outfeed table…pretty cool.

-- On the eighth day God was back in His woodworking shop! SteveW

View Dakia's profile

Dakia

7 posts in 1088 days


#2 posted 04-13-2014 04:42 PM

I really like the idea. Would you mind providing a few more pictures?

View RoadHogg's profile

RoadHogg

124 posts in 1388 days


#3 posted 04-13-2014 05:31 PM

Hi Dakia. I’d be happy to upload pictures. What details are you most interested in seeing?

The MDF slats on the bottom were to hold the filters in place. I abandoned this configuration in favour of three parallel filters vs. three series filters. The series filters killed the air flow dramatically.

I had initially intended to hang the unit from the ceiling but it ended up being way too big and heavy so I abandoned that idea too.

-- "The difference between school and real life is that in real life the tests come first, and then the lessons" -- Robert Lang, ReadWatchDo.com

View Hawaiilad's profile

Hawaiilad

2890 posts in 2482 days


#4 posted 04-13-2014 07:07 PM

What a great build. Got a question…you said at first you were going to mount the filter…do you find setting on the floor it works as well as on hanging on the ceiling? I have a hanging unit and since I need a outfeed table, I thought of building something like you have and installing the ceiling mount system in it.

-- Larry in Hawaii,

View changeoffocus's profile

changeoffocus

457 posts in 1078 days


#5 posted 04-13-2014 07:20 PM

good work, the multi use is a great idea.

View RoadHogg's profile

RoadHogg

124 posts in 1388 days


#6 posted 04-13-2014 07:21 PM

Hi Larry. I can’t say how effective it is on the floor as compared to hanging. I’ve never hung it. I know on the floor it seems to do quite well. The filters were bright white when I built in and within a few minutes running they turned yellow with fine dust. I find setting it to blow away from my work area is best as it will eventually circulate the air in the shop while pulling the dust away from me. Changing from series to parallel filters made a world of difference. The pleated filters I am using are about 4 micron I think.

-- "The difference between school and real life is that in real life the tests come first, and then the lessons" -- Robert Lang, ReadWatchDo.com

View Andygulfcoast's profile

Andygulfcoast

29 posts in 1298 days


#7 posted 04-14-2014 11:51 AM

I’m probably just being dense (my wife would tell you that it’s more than probable), but can you explain the difference series vs. parallel filters?

Thanks

View RoadHogg's profile

RoadHogg

124 posts in 1388 days


#8 posted 04-14-2014 01:58 PM

Hi Andy, no problem. I know it’s not a set of terms that everyone is familiar with, it comes from my experience in electrical/electronics.

Simply put, series = air passed through one, then another, then another.
Parallel = air passes through all three at the same time.

In series, you filter the air three times but you have only surface area of one filter.
In parallel, you only filter once but you have surface area of all three filters.

You can see on the box, I now have one filter on each of three sides. (you can’t see all three, but you can see two) It works really well. It blows a lot of air.

Let me know if I can clarify that further.

-- "The difference between school and real life is that in real life the tests come first, and then the lessons" -- Robert Lang, ReadWatchDo.com

View Dakia's profile

Dakia

7 posts in 1088 days


#9 posted 04-14-2014 04:12 PM

Ah, I think I get it now. My curiosity was more due to the fact that I couldn’t figure out where the air was being pulled from. I don’t have one of those fan units, but I seem to remember that they pull from the side. This just looked like it was blocked to me in the initial set.

View RoadHogg's profile

RoadHogg

124 posts in 1388 days


#10 posted 04-14-2014 04:26 PM

Yes, the pictures could be misleading as to the final design. At first I had only one inlet opening in the end that’s nearest the camera in that last picture. There were three filters but only one opening. That was far too restrictive and I got almost no air flow. I decided to cut openings in the right and left side also and install filters there. Now there’s three times the inlet capacity and the blower moves tons of air. I bet it would circulate the air in my 900 sq ft shop in a minute or so. You don’t want to stand in front of it too long, there’s quite a breeze.

-- "The difference between school and real life is that in real life the tests come first, and then the lessons" -- Robert Lang, ReadWatchDo.com

View choppertoo's profile

choppertoo

298 posts in 2774 days


#11 posted 04-16-2014 03:03 AM

Great post. Love that it doubles as an out feed table.

-- The greatest danger for most of us is not that our aim is too high and we miss it, but that our aim is too low and we reach it.. Michelangelo

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