Shopmade Air Cleaner FINALLY DONE w/pics

Jeff Bower

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Location
DSM, IA
Back in December I picked up an old squirrel cage blower for $5. I got it from a drywaller that used it to remove dust and speed mud drying, but he was getting out of the business because of lung issues. I told him I was getting it to make an air cleaner and he said, "Wish I'd thought of that 20 years ago." Made me think about why I wanted one...hopefully save my lungs from dust.

So far I've built most of the box for it. I used my Kreg pocket hole set for the 1st time and boy did that make things easy. I over drilled a few holes so there are some "bumps" in the MDF in a few places from the scew heads, but it seems to hold well. I have a roll of washable furnace filter that I will use for the first filter and then some finer filters for the second stage. I have it on a moble cab right now so I can move it from the lathe to bench when sanding at each. I hope to finish it up this weekend, but with the warm weather, outside clean up might take time away from that...here are a couple of picks. I'll update when I've done more and let you know how it works.

Any ideas on how to determine the CFM of the blower? It's a 1750RPM 1/6HP motor. :dunno:
 

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Looks like a good start, Jeff. You're going to appreciate having it. I don't have the answer to your CFM question, and from what I can see in a quick search, it looks like only the manufacturer of the blower cage will really know. I wonder if you could go through a supplier website (like Grainger's) and look for a cage of comparable dimensions, and see what those are rated at. :dunno: As I understand it, the CFM rating is proportional to the RPM, and the horsepower has no bearing on the equation.
 
Nice project. I built one 5 or so years ago with a whole house attic fan, wood scraps, and the paired furnace filters like you're using. The first "stage" is the washable blue filters, the 2nd stage are standard size HEPA furnace filters. The only two changes i recommend are adding casters, a handle or two, and a duplex outlet so that you can wheel it around the shop if you want and plug your sanders (or whatever) directly into it - it works better if it's close to the dust maker.
All in, i spent about $40 on mine. Someone tried to tell me that it was a waste of time, that the shop air cleaners needed to be engineered to circulate the air correctly or they did nothing but blow air around, collecting no dust and pushing dirty air into every far corner of the shop. I snicker quietly at that every time i clean / change out my filthy filters.
I've used mine in the renovation of my house also (drywall / plaster work). It'll eliminate a cloud in a couple of minutes - just make it small enough to fit through the door.
Great little project.
paulh
 
Nice project. I built one 5 or so years ago with a whole house attic fan, wood scraps, and the paired furnace filters like you're using. The first "stage" is the washable blue filters, the 2nd stage are standard size HEPA furnace filters. The only two changes i recommend are adding casters, a handle or two, and a duplex outlet so that you can wheel it around the shop if you want and plug your sanders (or whatever) directly into it - it works better if it's close to the dust maker.
All in, i spent about $40 on mine. Someone tried to tell me that it was a waste of time, that the shop air cleaners needed to be engineered to circulate the air correctly or they did nothing but blow air around, collecting no dust and pushing dirty air into every far corner of the shop. I snicker quietly at that every time i clean / change out my filthy filters.
I've used mine in the renovation of my house also (drywall / plaster work). It'll eliminate a cloud in a couple of minutes - just make it small enough to fit through the door.
Great little project.
paulh

Paul, thanks for the pointers...it is on casters already, but adding a plug or two to it would be benefical! When I got the fan I turned it on and let the suction hold a filter up to it while doing some sanding and the filter was caked with dust in no time...I know it will clear out some dust.
 
I finished this a few months ago, but never took pics to show it. It's crude, ugly and kinda big, but it moves the air and cleans it too! The shop is staying cleaner too. Not as much dust on top of everything, just piles of curlies!
 

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So Jeff, in the heat of the summer does it actually do some work of a fan and provide you with a breeze? If so, when working in winter, do you think it will make for an uncomfortable chill? :huh:
 
You'll enjoy having that, now and in the future. I've heard folks wonder why you would want to stir up the dust that is already in the air. That is a valid argument and that camp is entitled to their opinion.

My shop made one is running right now. I was just freehand routing the slot in my router table to do a miter slot extrusion upgrade. The cleaner is not stirring that talcum powder up any more than the router that made it I am pretty sure. By the time I get done typing this and submitting it, the gara. . .er, . . . shop will be well scrubbed and I can go back to work.
 

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:thumb: Same basic design as mine, but I can tell you from experience that the style filters you have are not going to stop much dust. (This I know as true... BTDT) You need to lay out a couple bucks more and get the paper style filters. they will last pretty long time and can be cleaned with a shop vac a few times before they are shot. with the fiber filters the chunks is all you'll catch the dust still is re-circulated by the fan.
 
So Jeff, in the heat of the summer does it actually do some work of a fan and provide you with a breeze? If so, when working in winter, do you think it will make for an uncomfortable chill? :huh:

Perzackerly why I have mine pointed at my work area... In summer it supplies me with the AC and in the winter it also keeps me cool under pressure as I sweat in a snowstorm when I do work.

I have it placed near the door so that it stops the dust from drifting into the Habitable part of the house.
 
:thumb: Same basic design as mine, but I can tell you from experience that the style filters you have are not going to stop much dust. (This I know as true... BTDT) You need to lay out a couple bucks more and get the paper style filters. they will last pretty long time and can be cleaned with a shop vac a few times before they are shot. with the fiber filters the chunks is all you'll catch the dust still is re-circulated by the fan.

Bill, I have paper filters behind the the cheap blue ones. I figure maybe that will help the paper ones last longer? :dunno:

Jonathan, I have another fan pointed towards me from behind at the lathe and then the air cleaner is behind the lathe. I to walk over to the outfeed of the fan and get a real blast of cold air from time to time. Will have to see what happens this winter.
 

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Jeff, I have some formulas to figure out the CFM of that blower. First I'll need the average wind speed either in MPH or FPM (feet per minute). You'll need to take about 12 readings from different areas of the opening. Tell me the average of those readings and I'll calculate the CFM. Did the motor come with the blower? Also, you can actually increase the CFM by adding some resistance the the airflow, (the technical term for resistance in airflow is called Static Pressure). Either by blocking a portion of the intake, exhaust, or by adding some duct. By doing that you will also decrease the amp draw of the motor. I've worked in the air conditioning industry for the past 11 years and I have 4 of those blower motors in my shop, but mine are direct drive instead of belt drive. My down draft box is very similar to what you built.
 
:thumb: Same basic design as mine, but I can tell you from experience that the style filters you have are not going to stop much dust. (This I know as true... BTDT) You need to lay out a couple bucks more and get the paper style filters. they will last pretty long time and can be cleaned with a shop vac a few times before they are shot. with the fiber filters the chunks is all you'll catch the dust still is re-circulated by the fan.

That is all he needs for being a spinner.:D:rofl: I have a blower like that but stands over 2' tall and came out of the furnace with a 3/4 hp motor.:eek:
 
I have a small shop not enough room to have a floor style filter system.

So I mounted the fan system with the shaft vertical this allowed me to mount it in a smaller box in all dimensions.

At a little over 5'9" with a ceiling of 7'10" I can walk under the
the filter system.

I purchased a bag filter that fits inside the box. I had a set of filters inside the front of the box, but when I moved the system I had to mount it close to a light & couldn't open the side door so I put a sheet metal angle on the front of the system & slid 2 pleated filters in behind the angle.

The system is three speed.
 

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Bart, you hit on my next question. Floor space will be a premium with my new shop and wondered about hanging it. Bag filter?

Jonathan

The bag filter has a rectangular frame at the front that slides into a slot in the front of the box & holds the front of the bag open. It fills about 1/2 of the box & catches the finer particles. Do you see the narrow gray area just inside & back from the front that is the frame. If you look inside behind the metal frame at the bottom you can see it looks kind of uneven not a straight line between a light color & the OSB that is the bag. I purchased this at Grizzly but am not sure if they still sell them. It works very well.

I think your shop is a bit bigger than mine which is only 13'5" x 24'5'.
 
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Jeff, I have some formulas to figure out the CFM of that blower. First I'll need the average wind speed either in MPH or FPM (feet per minute). You'll need to take about 12 readings from different areas of the opening. Tell me the average of those readings and I'll calculate the CFM. Did the motor come with the blower? Also, you can actually increase the CFM by adding some resistance the the airflow, (the technical term for resistance in airflow is called Static Pressure). Either by blocking a portion of the intake, exhaust, or by adding some duct. By doing that you will also decrease the amp draw of the motor. I've worked in the air conditioning industry for the past 11 years and I have 4 of those blower motors in my shop, but mine are direct drive instead of belt drive. My down draft box is very similar to what you built.

Bill, thanks for the offer, but I don't really need to know what the cfm is...all I know it that it cleans the air well just like I hoped it would. :thumb:

That is all he needs for being a spinner.:D:rofl: I have a blower like that but stands over 2' tall and came out of the furnace with a 3/4 hp motor.:eek:

Al, mine is the same. About 2' by 2.5" but only a 1/6 hp motor. It sits on top of a tool cabinet that is behind the lathe.
 
Jeff, do you think it would do as well hanging in the middle of the shop from the ceiling? Or would you make some changes if you did that?

I think it would work just fine hanging from the ceiling. I would have done that, but I only have 8' ceilings and I would be banging my head on it all the time.
 
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