the concept looks easy enough, my thought was take a couple of high filtration furious filters like 3m's filtrete, stack them 3-4 deep put a squirrel cage fan to pull are though and mount this on my garage ceiling, the one big problem is the filters are a little bigger then I would like
Richard
Furnace filters sorry, spell check got me again
Richard Clements asks:
Regular furnace filters on 20x20 fan boxes work pretty well. One on each side is best. I tape them on, others get fancier. The incoming side nasties up fastest. Peel, toss and put the next 99 cent special in place. After a couple years, the fan motor gives out. Spend 14 bucks for another one.
I've seen regular furnace filters as small as 12" x something or other. That should work on your squirrel cage blower.
Charlie Self "Give me golf clubs, fresh air and a beautiful partner, and you can keep the clubs and the fresh air." Jack Benny
I use the 16x20 in a box hung from the rafters. Smaller filters should be available. But I only use one fine filter preceded by a standard (99 cent) fiberglass filter. If you just use the fine ones, they clog very fast. The coarse one catches all the big stuff and some of the fine as well.
There are pretty good plans in the book Controlling Dust In The Workshop© by Rick Peters. I built one with a three speed 1/3 hp blower motor with squirrel cage. (the plans call for a 1/15hp motor) Therefore, everything had to be upsized to fit the blower housing inside. Fortunately, the filters cost the same irregardless of size.
Furthermore, there was a discussion was going about switching the different speeds about a month or so ago,. Someone suggested a on/off switch and two three-way switches. Thats the way I went and it works very well.
Not a set of plans but enough info to build one that fits your needs - an outfeed table / downdraft sanding table / ambient air cleaner which uses an old furnace squirrel cage blower and some pleated cartridge filters - diesel truck filters work pretty well.
Mine are 14 x 25 stacked low filtration (for chips) high filtration then a high filtration pleated cloth bag type. I built it into a table with holes in the top so it can also be used as a sanding table. Air exhausts downward under the table. It has a double squirrel cage making it a lower profile.
I believe the combined surface area of the filter including the folded area needs to be large enough in order to ease the air flow. Therefore, a large filter may not be a bad idea. You may want to look up a dust collection book to look for the formula to determine the right size of filter for your blower.
If you really need it to be low-profile, I think you can use two or three filter cartridges (that normally use in a shop vac) to get the same filter area in a very low profile. But they probably cost more and the way to mounting them is more complicated than regular filters. And the "cost more" part "probably" defeats the purpose of making an air cleaner yourself instead of getting a store-bought one.
Jay Chan
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