air cleaner questions and thoughts

[Rick Moyer]

I think it is time for me to improve my air filtration over the box fan and filter I currently have been using. I have read many of the threads concerning squirrel cage blowers, and I would consider building one of these IF I could find any cheap locally, but so far no luck. Anyway, I have some questions and thoughts.
Thoughts:
I would like to be able to have the thing run for a period of time after I leave the shop (timer, I presume)
I would like to not have to purchase proprietary filters
I would buy one if getting everything I want is not practical for me to construct myself (e.g., the timer issue)

Questions:
I need to know the recommended CFM, for a 21x21 shop 9 ft ceilings?
If you (or your Dad, Glenn Bradley) have a purchased unit, what are your thoughts on it having used it for some time?
What ones get the best reviews? (I guess I can research this myself, unless soeone already knows.)




Before someone says it; Yes I try to collect most of the dust at the source, Yes I have a DC cyclone (although not hooked up yet), Yes I frequently wear a dust mask or respirator (and eye and ear protection,too). I want to be able to clean the air of the fine stuff that floats around, and I want to haev it run after I leave the shop for a period of time.

P.S. I spent the past hour looking for reviews. Although I have read individual reviews, I cannot find any comparisons done by any of the woodworking mags, etc. Anybody point me to any of these?
Looking for recommendations for purchasing mainly, unless I can find everything I need to get the functioning i want.

[Alan Schaffter]

Air cleaners are pretty basic. Just about any fan/squirrel cage fan will do. You just need to decide how many times per hour you want the air to be filtered.

Turn over rate (times per hour) = CFM of blower x 60 / (L' x W' x H') e.g. CFM x 60 / 3969 for your shop. Typical air cleaners handle 400 to 1500 CFM which would yield turnover rates of 6 times per hour and 22 times per hour. More times per hour is better.

Once you decide on turn-over rate then find a fan unit the will deliver that. Keep in mind some blowers are noisier than others.

Next, decide on filtration performance (how small of particles you want to filter) and if you want to be able to clean or wash the filters. Unfortunately many furnace type filters won't remove the small dangerous particles and most are not washable, for that reason many air cleaners use multiple stacked flat filters, passive electro-static filters, washable fabric pocket filters, or a combination of filters.

Now you have all the info you need to decide if you want to build or buy one.

Other than CFM and minor whistles and bells, there is little difference between most commercial units.

You really don't need fancy remotes or multiple speeds. I got a used jet with burned out control unit really cheap so decided not to build one like I had originally planned. It uses both a fabric pocket filter and a standard furnace filter. I put a 3-speed pull chain fan switch on it to control the fan speed and replaced the wall switch on the ceiling outlet circuit I had prewired with an inexpensive 60 minute spring timer so I can set it to run after I leave the shop.

PLEASE, PLEASE READ Howard Acheson's post, especially the last two paragraph's, in the link in JohnT's post below!!!!!

[JohnT Fitzgerald]

Rick - Alan beat me to it. good advice. Keep your eyes open for furnace or HVAC repairs/replacements, maybe call a local contractor to see if he has an old unit he's trashing. And the timer suggestion is just what you need.

There were plans for a shop-made air filter in ShopNotes a while back...and you should check out this threadL http://www.sawmillcreek.org/showthread.php?t=87627

[Scott Vincent]

Im planning to add one to the shop as well. I was thinking of using leftover dust bags(5 micron) as a prefilter before the smaller ones. Figured it might help and they could be cleaned vs tossed. Plus I kept them and I really hate not using stuff that I have laying around. Good luck.

[David Hostetler]

I am planning on building one for my shop, wired similarly to the Jet unit above. 3 speed fan control switch as well. (The wiring is there already for a ceiling fan...) I am planning on using an old 110v HVAC fan, a simple MDF enclosure, and and a series of 2 3M Filtrere allergen filters (95% filtration at .3 microns allegedly).

I would honestly prefer one with a remote, and its own timer etc... on board, but I have found NONE that filter under 1 micron...

Do any of them take standard HVAC filters sizes that we could run the Filtrete units in?

[ROY DICK]

http://lumberjocks.com/projects/16404http://

Roy

[David Hostetler]

Corrected link...

http://lumberjocks.com/projects/16404

If this is against he posting rules (I honestly don't recall...) Go to lumberjocks, and do a search for project #16404.

That is actually one of the shop made filtration units I am using for inspiration...

I do think the 3/4" ply is too thick / heavy. I was planning on using 1/2" stuff.

[Prashun Patel]

Check out ShopNotes Small Shop Solutions. They sent me this with a 1year subscription 2 years ago. It has plans for a squirrel cage blower and regular furnace filters (2 on the intake, 1 on the exhaust). Works great, and you can size it to your liking.

IMHO, while bigger is better, even the smallest of air cleaners will improve air quality if placed properly.

[Jim Rimmer]

The Shopnotes plan is very much (exactly) like the one on the Lumberjocks link and Shopnotes has the complete construction plans.

[Rick Moyer]

Thanks for the responses so far. Please note: I HAVE read the threads that some have referenced. I also know that this is not the total solution to dust control (see my last two paragraphs in the OP). IF I can find a squirrel cage blower I MAY decide to build one, however I would like some opinions of those who have purchased and are using a particular model and their thoughts as well. It appears the JDS gets great reviews, although I still have not found a magazine review/comparison. I should have said in the first post that I would prefer a smaller micron filter w/o having to lose too much CFM. I also have other things to get done besides building an air cleaner, but I won't rule it out.

[glenn bradley]

I have a shop made unit that I use in addition to my 2HP cyclone and my 1HP AFF bagger. Even though the area seems clean, it is amazing how much this guy picks out of the air. I clean/replace the filters every few weeks (got a boat-load of them on clearance at Target for $1 each).

Dad got the JDS which generally wins the bake-offs for actual material collected. Built mine out of scrap T1-11 that a neighbor was throwing out:

http://www.sawmillcreek.org/attachme...8&d=1150229969

http://www.sawmillcreek.org/attachme...9&d=1150229977

The open side has a cover that is held on by magnets. It hangs over my bench area and runs off one of those cheap Christmas light remote controls from the BORG.

[David Hostetler]

I have a shop made unit that I use in addition to my 2HP cyclone and my 1HP AFF bagger. Even though the area seems clean, it is amazing how much this guy picks out of the air. I clean/replace the filters every few weeks (got a boat-load of them on clearance at Target for $1 each).

Dad got the JDS which generally wins the bake-offs for actual material collected. Built mine out of scrap T1-11 that a neighbor was throwing out:

http://www.sawmillcreek.org/attachme...8&d=1150229969

http://www.sawmillcreek.org/attachme...9&d=1150229977

The open side has a cover that is held on by magnets. It hangs over my bench area and runs off one of those cheap Christmas light remote controls from the BORG.

That's no squirrel cage. That looks like an automotive electronic fan. Not a bad idea IF it can pull enough air through to be effective... Generally speaking, the auto fans are 14" or 16" though...

[Rick Moyer]

Glenn, any thoughts on how yours compares to your dad's? I see you have two filters before the fan and one (better?) after. Why not all before the fan? I don't even know: Do the ones like JDS pull air thru the fan motor? I liked the idea of NOT pulling air thru the fan motor, particularly (no pun intended) when spraying finishes. this seems to be to be the reason for using a squirrel cage, otherwise one could make a setup such as yours. Anyone can jump in on this.

[glenn bradley]

Sorry Rick. I don't know how I missed this. My dad's has much more sophisticated filters and works faster and quieter than mine. On the other hand, my shop made one uses filters that I seem to be able to find on sale or clearance for a very low price and it cast 1/10th the price. That being said, I'd trade up in a heartbeat but mine beats the pants off of nothing.

[Howard Miller]

Harbor Freight has this unit http://www.harborfreight.com/cpi/cta...emnumber=91393

Don't know much about it.