air cleaner questions and thoughts [Archive] - Sawmill Creek Woodworking Community

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Rick Moyer

11-28-2009, 9:30 PM

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

11-28-2009, 10:37 PM

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!!!!!

http://www.ncwoodworker.net/pp/data/500/medium/IMG_2759.jpg

http://www.ncwoodworker.net/pp/data/500/medium/IMG_2757.jpg

JohnT Fitzgerald

11-29-2009, 8:03 AM

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

11-30-2009, 12:09 AM

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

11-30-2009, 1:00 AM

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

11-30-2009, 8:42 AM

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

Roy

David Hostetler

11-30-2009, 11:23 AM

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

11-30-2009, 11:43 AM

Jim Rimmer

11-30-2009, 2:05 PM

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

Rick Moyer

12-01-2009, 7:12 AM

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

12-01-2009, 10:20 AM

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/attachment.php?attachmentid=40748&d=1150229969

http://www.sawmillcreek.org/attachment.php?attachmentid=40749&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

12-01-2009, 1:46 PM

Rick Moyer

12-01-2009, 6:06 PM

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

12-28-2009, 1:01 AM

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

12-28-2009, 8:17 AM

Harbor Freight has this unit http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91393

Don't know much about it.

Mike Cruz

12-28-2009, 8:45 AM

Question: You seem to have yours pointed towards the wall. It was my understanding that your best bet is to have the air filter along the wall, creating a circular motion along the walls...around the perimeter of the shop. Why did you install yours to bow directly AT a wall? I'm not saying you did it wrong. Just curious....

Rick Moyer

03-27-2013, 6:56 PM

Update to my 3+ year old thread:
Finally received and installed a JDS HP unit. Seems to be a nice unit. Have not really used it much yet, just got it hung up and plugged in.

Jim Neeley

03-28-2013, 2:11 AM

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.

Whether you buy or build, I recommend going with aftermarket filters, such as the ones supplied by Wynn Environmental, as they filter far better than any furnace filter you will find.

I picked up some for my two Jet units and my Dylos particle monitor loves me for it!! :)

Alan Schaffter

03-28-2013, 9:06 AM

Whether you buy or build, I recommend going with aftermarket filters, such as the ones supplied by Wynn Environmental, as they filter far better than any furnace filter you will find.

I picked up some for my two Jet units and my Dylos particle monitor loves me for it!! :)

I don't know, believe it or not, here in my little berg in E. NC we have both Flanders and Camphil-Farr filter factories (and Stanadyne for fuels and liquids :) ), both of which, believe it or not, supply "super" filters to DoD and less demanding applications. Here they provide un-rebranded filters to some of the local retailers. They also supply filters to companies who re-brand them under various names like 3M/Filtrete, Purolator, etc. Wynn likely gets their filters from one of these major filter manufacturers. You just need to check the AHSRI ratings to find the best ones for fine dust. But, you are right, most standard furnace filters aren't up to the challenge. Also, since most have very limited filter surface compared to big pleated cartridge filters, they should be changed fairly often.

Ole Anderson

03-28-2013, 11:59 AM

I have Rockler's DustRite ambient air cleaner which I used to replace my dual filter box fan which just didn't have the chops to move much air through two filters clean, let alone filled with dust. I didn't want to go the home brew route again, so I moved on and have been very happy with the unit for 2 years now. Well, it seems they don't carry it now, just the filters for it. Oh Well. The Jet seems to be the most popular and got good reviews if you go that way.

Michael Dunn

04-01-2013, 5:01 PM

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.

I built this exact AFD three years ago. I bought a 465 CFM squirrel cage blower for like $75 on amazon. I made it from 3/4" birch. I put 4- 3/8" hook eyes it the joists above and 4 into the AFD itself. Then I used spring clips to connect them. I up an outlet in the ceiling near the AFD and wired it to a timer from HD. 1, 2, 4, and 8 hours. Honestly I haven't used it a ton until lately. I can't really comment on it now since I'm upgrading my DC system and at the moment so I have an obscene amount of dust everywhere. I run it at night. I do notice the air smells fresher. My bench and tool surfaces are still caked with dust as expected since I haven't collected well at the source lately. I'll post updates when I'm closer to completion.

Michael W. Clark

04-01-2013, 5:33 PM

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.

Alan,
Not to hijack, but can provide a few details on how you did the timer?

Thanks,
Mike

Alan Schaffter

04-01-2013, 7:37 PM

Alan,
Not to hijack, but can provide a few details on how you did the timer?

Thanks,
Mike

I pre-wired a ceiling outlet before I installed the drywall. Unfortunately it is not visible here

http://www.ncwoodworker.net/pp/data/500/medium/IMG_2759.jpg

The air cleaner ceiling outlet is controlled by a mechanical spring timer that replaces a switch in the main lighting switch box:

http://www.ncwoodworker.net/pp/data/500/medium/IMG_2757.jpg