The Birth & ReBirth of an Air Cleaner/Filter

Sean Wright

Member
Messages
902
Location
WNY, Buffalo Area
Part1

As I am still waiting for the funding to come through, so I can add a dust collection system to the shop.... I decided that I would build an Air Cleaner/Filter. At least that would be a start toward better air quality in the shop (and in my lungs :eek: )

I initially set out to make something along the lines of what Bill Simpson posted here:
http://familywoodworking.org/forums/showthread.php?t=3030&page=2

I started with a floor fan from Target. I removed the stand, and determined how big of a hole I would need for both sides of the fan (11 in dia.). Then I built a Circle Jig for my Plunge Router.

More on the Circle Jig can be found here:
http://familywoodworking.org/forums/showthread.php?t=3560

After cutting circles in the front and back for the fan housing, I set the fan in place to make sure it had enough clearance (as pictured below). Then I boxed in the fan, essentially making a fan housing.

continued...
 

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I'm thinking that'll do well. Here's what I did with an 1100 CFM gable fan and some scrap the neighbor was gonna throw out. Works great. Gotta clean the filters about once a month.
 

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The Birth & ReBirth of an Air Cleaner/Filter - Part2

Part 2

Then I put in small wood strips to act a stops to keep the filters from being pushed into the box. I also attached a back panel opposite the fan housing. I put a filter (air intake) in one side as seen in the 3rd picture. The 2nd picture shows a filter sitting in place infront of the fan housing (air exhaust). The reason for the filter on the exhaust end, was to catch any dust that made it through the first filter or was sucked in through any "air leaks" in the case. The exahust filter also serves the purpose of slowing down the air coming out of the unit. This way not more dust is blown around the shop.

After looking at the size of the unit, as best seen in the 3rd picture, I determined that the entire unit was going to be way too big, to hang in my shop, given the height and space restrictions that I have. So........

The ReBirth
I decided that inorder to accomidate the size restrictions of the shop, I would do away with the side mounted individual parallel filters, shorten the box and mount the filters in sequence on the end of the unit, directly across from the back of the fan housing. In theory this revised design will do a better job filtering the air. :thumb:

I essentially extened the sides of the fan housing back by 6 in on each side. This allows enough room for the electrical portion, and puts a bit of space between the filter and the suck end of the fan. The reduced "foot print" of the unit can been seen in the 4th picture. The extension of the fan housing can been seen in the 5th picture.

I then put a 2in wide piece on each side 3/4in beyond the 6in fan housing extesnion. This left a space wide enough for a filter to slide in between. This can be seen in the 6th picture. The 7th & 9th picture show the filter inplace. Then I took angle bracket cut to 18in long and screwed it to the top and bottom of the front and back. This allows for the outside intake and exahust filters to be mounted. You can see the top bracket in place on the intake end in the last picture.

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The Birth & ReBirth of an Air Cleaner/Filter - Part3

Part 3

The 3rd picture shows the unit from the intake end where you can see the edges of all 3 filters.

As far as the electrical end, I choose not to hardwrire the fan in. My reasoning for this was it would make swapping the fan out easier, if the need arises. I put a single outlet plug inside of the box to prevent any dust from getting into an open unused outlet. The outlet is tied to a box with a switch which faces down. This way I can turn the unit on and off as needed. The fan itself has 4 power settings. I left it set to the highest setting, relying on the unit switch to run the power. The bottom of the unit with switch can been seen in the 4th picture. The 5th picture shows the electical boxes from the top down. This was taken before I attached the top.

I put 4 eye bolts in the top of the unit to allow it to be suspended in the shop (picture 6). I will be attaching it to eye screws with snap-links. (picture 7) Mounting will be the last step.

I fired it up and seemed to be pulling a decent amount of air through.
 

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I'm thinking that'll do well. Here's what I did with an 1100 CFM gable fan and some scrap the neighbor was gonna throw out. Works great. Gotta clean the filters about once a month.

Glenn,

I'm assuming that your air cleaner is totally enclosed (only opened for the picture).
How dusty does the 2nd filter in get? Does the outer one let alot of dust through?
Also do you think it makes a difference having it running in your shop?

Thanks !
 
Great Tutorial. I have a huge industrial fan and was wondering what to do with it. I think I will steal your idea if you don't mind. Thanks !

Darren,

You are welcome to the idea. :thumb: Post some pictures if you make one!

A couple of things that I can offer:
- The size of the unit is based on 2 things - The Fan Size and The Filter Size.

- If you are planning on hanging the unit...Make sure that it is sturdy enough to be hung from the eye bolts..... Especially if you will be walking underneath it. :eek:

- If I was doing it again, I might consider putting in a timer switch (like for a bathroom fan). This way I could set it to run for an hour after I was done working, and then shut down.
 
Glenn,

I'm assuming that your air cleaner is totally enclosed (only opened for the picture).
How dusty does the 2nd filter in get? Does the outer one let alot of dust through?
Also do you think it makes a difference having it running in your shop?

Thanks !

Normally enclosed, as with blade guards . . . removed for clarity :D .

I have actually stopped using the second internal filter. It was never dirty and the airflow is better (a little, typical overbuilding on my part).

It definitely sucks up some superfine dust. Whenever I clean the filter I see what I would otherwise have left in the air. Mine is mounted high so it is picking up what is floating around v.s. stuff being blown at it.

I think after you use yours for awhile you'll see just what I'm talking about. I really like your design. Mine should have had a larger internal cavity behind the fan (or so it seems from what I read). The small space could be restricting the unit's efficiency. It's made of scrap so I may try another version later on.
 
8" to 10" car/automobile electrostatic radiator fans are also handy for small fan units and are only 12 VDC. some of the profiles are pretty flat.
 
Update

I've been using the air filter for a while now, and it is definatly picking up dust from the air. The outer intake filter is now a light shade of brown from the wood dust particles that it is holding on to.

I'm debating removing the outer filter and just running it with the inner filter and the filter on the out put side of the fan. Mainly to increase effenciency.
 

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Hey, Great looking fan.... Mine works well and it is no where near as well built... Even when I don't do any sanding and such, the filters show dirt in a short time, so I know it is picking up something out of the air.

The old Suspender/belt sindrome is showing Mr Doubting Thomas :p

The junction box and outlet inside to accomidate the plug for the fan.... Just in case the fan idea doesn't work you can still use the fan... rather than cutting off the plug and wire direct to the switch.... This added expense and effort but it is the conserative approach. :eek:

T
 
I'm debating removing the outer filter and just running it with the inner filter and the filter on the out put side of the fan. Mainly to increase efficiency.

As I mentioned in my post, I did just that. Pull the second filter and tap it over a dark surface that will show even the really fine dust you may have caught. If there is nothing, I'd think about leaving it out IF there is a big jump in efficiency.

Mine has a design flaw (not a big enough space for the fan) so going to a single filter made a big difference. Oh great . . .thanks for reminding me. I'm supposed to rebuild that thing now that the weather is warming up.:D On the bright side, this would be a perfect time to steal your great idea for a timer switch. After using mine for awhile I definitely agree that that should be standard in anyone's design.
 
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