Shop air cleaner

[John T Barker]

I've gone without dust collection and clean air in my shop for too long and think it might be time to build myself an air cleaner and bring in dust collection at my larger tools. I've done a few online searches for plans for shop made air cleaners and see that many people use the simple design of a fan pulling in the air through filters. On the other hand I am seeing that there are some people saying these fans are not strong enough and will do little in terms of cleaning the air. I'm at a loss as to what to do. I can't spend hundreds on more powerful fans and such.

I'm wondering what you all do. I'm thinking of perhaps a pair of the less effective cleaners might help approach a more powerful and expensive unit. I'd appreciate any feedback and apologies if this is an overdone topic.

John

[George Bokros]

Buy a regular shop air cleaner with a cleanable pre-filter and a washable bag filter. I think I paid $300 -$350 for mine. Get something designed for the job at hand.

[David Hawxhurst]

build one. see this article http://billpentz.com/woodworking/cyc...ir_cleaner.cfm
works very well.

[Phil Thien]

Build or buy, they all more or less work on the same principles.

You do need a squirrel cage fan/blower. A conventional box (axial) fan will work, but it won't move 1/10th the amount of air through the filters as a blower pulled from a furnace.

[John T Barker]

Why not an attic fan that pulls 1600CFM? Would that work?

[Phil Thien]

Why not an attic fan that pulls 1600CFM? Would that work?

Not that well, they can pull 1600CFM but not through the resistance of a filter, the filter would reduce the CFM dramatically.

[John T Barker]

What rating of air movement are you saying I need from the furnace fan?

[glenn bradley]

Why not an attic fan that pulls 1600CFM? Would that work?

This is what I used. The plans called for two entrance and one exit filter. The fan once faced with the filter's resistance move little air. If I pull the filters, its an animal. I finally settled on two entrance filters of a more open media than originally spec'd and this works well as an ambient cleaner. To the folks that think these things are not useful, I have a 2HP cyclone, a modified single stage unit and a couple of shop vacs on duty. The outer filter on the ambient cleaner still needs to be cleaned about once every month or so. That being said, these types of cleaners are "in addition to" devices. That is; they enhance the usual dust and chip gathering devices a woodshop might use. They are a far cry from a total solution dust collector IMHO ;-)

[Sam Puhalovich]

I have a ClearVue as the primary chip/dust collector.
I have 4 ambient air cleaners.
1. A ceiling hung 'box' with a squirrel-cage from a HVAC unit w/ 3 filters in front of it. It's used whenever the I use the sander, and, if I use the band saw, or table saw for long periods.
2. A horizontally-hung ceiling 20" box fan with a single MERV 7 filter attached. It's 'hooked' to the lights switch ... and always ON.
3. A 12"x20" MERV 7 filter installed in the side of the house HVAC return air plenum (basement shop) ... the house fan is always ON.
4. A 'down-draft' assembly and work-table with a squirrel-cage from a HVAC unit ... used when extensive ROS sanding.
I typically clean all the filters about every 4 weeks ... and replace them about once-a-year.
I was majorly surprised at the efficiency of the ceiling box fan. Initiated after reading a WOOD magazine article ... testing air cleaners ... was found to be just as effective.
Julie Moriarity did a similar test a few months ago and found the same result.
The 20" box fan is so effective that I am considering to build a 4th 'portable' ambient air cleaner.
One that I would use positioned close to where-ever I am doing small operation hand-sanding.

Based on the WOOD magazine article, Julies findings, and my own experience ... I would spend the money 'elsewhere'.

[Rick Thom]

Here's one I built based on HVAC a few months ago. Seems to work well.

[Art Mann]

Hey Rick,

I went to the link and tried to view the photos. You have to be a member of the forum to see them. Could you possibly post links that will work here? I am definitely interested. Thanks

[Rick Thom]

Hey Rick,

I went to the link and tried to view the photos. You have to be a member of the forum to see them. Could you possibly post links that will work here? I am definitely interested. Thanks

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I wanted a higher capacity air cleaner than my 450 cfm Delta unit so I thought I would build one to suit my needs based on a furnace blower setup. My objective was improved air circulation, higher volume flow and good filtration.

I scored a good lightly used furnace blower unit equipped with a 4 speed 1/2 HP motor from Ed in Leaside. It's off a current model high efficiency furnace. The blower setup I got is quite large and heavy measuring @ 17" deep x 14" wide x 19" high and tips the scale about 50 lbs. as a guess. The setup includes a 10" inside diameter squirrel-cage fan that is mounted on the motor armature shaft direct drive.

I used 1/2" plywood G1S to construct the box which measures 33" long x 18" wide x 20" high. It required @ 2/3 sheet of plywood. I left a space of @ 2" around the blower for air circulation to cool the motor and provide air source for the fan.
The plywood case is simply rabbetted around the plywood panels and glued but with glue blocks added inside for extra joint strength.

The major decision on this project was type and source for filtration. The blower housing had 10" dia side ports for air source making side-mounted filters the natural choice. I decided to go with rear-mount filters instead because I could get higher capacity bag-style filter which was washable and having a suitable filtering capability for about the same cost of 1 round of throw-away furnace filters. I ordered the washable permanent 1 micron filter and it's replaceable 5 micron primary companion from Grizzly Tools at a cost of @ $100 delivered. http://www.grizzly.com/products/1-Mi...r-G9956-/H2451 , http://www.grizzly.com/products/5-Mi...r-G9956-/H2452. These filters measure 16 x 20" and the bag filter when fully inflated measures @ 16" deep which is the reason the cabinet is so long. These filters are the ones recommended for high capacity fans and are also used for sanding/ down-draft tables.

I installed and wired a 60 minute timer and also a 3 position switch to control motor speed ( Hi, Lo, Off). I would have preferred to have a 6 position rotary switch but couldn't find one locally. I wired 2 of the 4 available motor speeds which should be adequate for my needs. Having read a good number of recommendations from other builds, I installed an electrical box vapor barrier over the back of the electrical box to ensure the fan wouldn't suck dirty air through the electrical box rather than through the rear filters which would screw up the electrical switches in a hurry.
I simply installed 1/2" metal cloth over the blower exit for safety reasons. I may experiment with an air diffuser at some point if I'm not satisfied with air flow.
I hung the unit from 4 eye bolts installed in the cabinet. I have low headroom in the shop so it's not idea for air circulation but this unit is powerful enough to overcome the room deficiencies and obstacles. I can feel the air moving around the shop.

I'm not sure what the cfm rate is for this blower but the air cleaner equipped with these filters will certainly meet or exceed the recommended 8 air changes/hour in a good sized shop. I could add other types of filters if I wished and will use normal furnace filters when it's necessary to replace the disposable primary filter on this unit.

I built this unit over the course of a few days but it's realistically about an easy one day job once you have all the components in hand. The cost of the materials is in the $100-150 range depending on filter choice, plus a furnace blower. Used furnace blowers can be had cheaply or maybe even free from furnace installation companies.

If you've got the time and inclination, and need a good air cleaner, a shop built one like this is can be at least as effective as most units available through retailers, and at a fraction of the cost which makes it very good value in my book.

[Lornie McCullough]

Rick,
This is a very carefully considered project! I appreciate the thought you put towards this project, and the care in the execution. You created an air cleaner that any woodworker could build at a value better than any storebought (in my humble opinion). I love seeing this kind of post!

Lornie

[Phil Thien]

Very nice execution, Rick!

[Craig Richmond]

I have a 20x20 shop and picked up a Jet air cleaner off of Craig's list for about $225 that was hardly used and it works great for me. Now, If I had access to the fan like what Rick did in the post above, I would have made my own. I am sure his moves more air than mine. If you build one make sure you put a pre-filter on it as that will collect the larger particles and save you from washing your main filter so much. You will be surprised how much they pick up.