Ambient air

[Bill Eshelman]

Does anyone have any opinions on an ambient air filter? I am trying to make it possible to keep working rather than run out of the garage every time I use something without a dust port ( Palm sander, circular saw, router on dovetail jig etc...).
My shop is about 18' x 12' x 8'
I just got a little bonus check from work and I think this would be a wise way to spend it.

Thanks.
Bill E

[Greg Cole]

Bill,
I made one from 2 bathroom fans from the BORG @ $20 each. Each one is about 100cfm out of the box.
I made a plywood carcass, made a fan to suck in on each side with a el-cheapo furnace filter (woven fibergalss) for a pre filter. The filters have to be cut to fit but cutting the 12 X 24's in half, I get a filter for each inlet.
Both fans exhaust goes into a small internal chamber and out through 3M ultra allergen style filter (the pleated paper style). Again this filter is cut to fit, but the 12 X 24 size gives me a filter for the unit and a spare.
Total cost was MAYBE $60 -70 for the 2 fans & 2 filters (I had the switch & junction box lying around). Does as good a job as the Delta versions I've been around.
I've noticed alot less dust build up on flat surfaces since I made it, so it's doing some good at least.
$0.02 donation.....
Greg

[Dan Forman]

Bill---It's not a replacement for dust collection at the source. It will clean the air over the course of a couple hours, but that won't make it any safer to be in the shop when you are actually working. A better bet would be a downdraft table for sanding, circular saw with a dust port (Porter Cable makes one, as does Festool), I don't know what would work for routing dovetails, but there are a few routers with dust collection features.

The other approach would be to use the dust creating tools outside the shop as much as possible, and wear a dust mask when doing so.

Dan

[Brian Dormer]

I have a 16x16" box fan from Wal Mart - slapped on a couple L-brackets and mounted 2 16x16 furnace filters over it (although if it's running on high - there is enough suction that they don't move anyway). It's not a great filter, but better than nothing.

Maybe you should consider a small (3/4 to 1 hp) dust collector. I have a very nice Craftsman (OEM'd by Delta) that was about 120 bucks on sale - and came with 10 feet of hose and a big "dust mouth". I use it with just about every tool in the shop - makes a huge difference in the amount of dust in the air.

I did replace the bag with a .3 Micron I got from Grizzly for about 30 bucks. You really want to filter to 1 micron or less. The dust from 1-3 micron is the stuff that's going to kill you.

[Jack Hogoboom]

Bill,

Rick Peters wrote a great book on workshop dust control. According to him, an ambient filter is a complete waste because it is filtering the air that has already been through your lungs. According to him and others, dust collection at the source is the only way to really protect yourself.

Hope this helps....

Jack

P.S. I read the book right AFTER I blew $275 on a ceiling filter system.:rolleyes:

[Wilbur Pan]

I'd have to disagree with the assertion that air cleaners are useless. Certainly, there's nothing that beats collecting dust at the source, but that assumes that collecting dust at the source is an attainable goal. Real world measurements indicate that it's not. Also, the best cyclone in the world isn't going to filter the free floating dust at all if it's not picked up at the source.

Furthermore, air cleaners are surprisingly effective at removing dust particles from a room IF they are appropriately sized for the room. In my book, the conventional wisdom of 6 air exchanges per hour is way way way too small. Going for 25 air exchanges per hour will clear the air of 99.999% of dust particles in just over 20 minutes even if the efficiency of the air cleaner is only 75%.

It's not hard to achieve this level of air cleaning. A typical 12"x24" profile air cleaner (Jet AFS-1000B, JDS 750-ER, Delta 50-875, Steel City 3 speed 65105, and any other 3 speed model that is rated at a top CFM of 1250 or so, but is really 750 CFM in real life) will clean a 20' x 10' x 8' area 25 times an hour. For those of you with bigger shops, just hang more air cleaners. It's probably more cost effective than trying to upgrade your cyclone system, and with multiple units, you'll get better coverage.

So, Jack, I hope you feel better now about your $275. ;)

[David Cramer]

My ambient filter does a great job and the electrostatic filter proves this out. Think about it, all that dust on the filter has not gone through my lungs, or even close to it. It is airborne dust and was sucked into the filter by the draw the ambient dust collector creates. I blow mine out once a week with compressed air, outside of my shop. If the wind is blowing right, you can really see how much dust has been captured by it. I'm not an expert, but I too believe your $275 was not a waste Jack. Actually, I think it was well spent, but that's just my opinion.

Dave

[Andrew Williams]

I use my shop-built enormous ambient air filter every day and it makes an absolute world of difference. I sized it to exchange all the air in the shop every 3 minutes and it does darn near that.

[Matt Meiser]

In my opinion, the air filter is worth it. I find that it does a decent job of pulling ambient dust out of the air. You are still better off catching at the source with good dust collection, hoods, etc, and when doing dusty operations, you should wear a mask. However, I think the dust filter helps keep the overall dust level in the shop down, making it cleaner which is good for you and for the finishes on your projects.

One problem I've noticed with mine though is that it doesn't work worth a darn when I forget to turn it on. :rolleyes: Wish I could find a solution for that.

[Jim Heffner]

You might want to make air filter yourself...I did. I picked up a squirrel
cage blower with a directdrive 115 volt motor, built a plywood box around it made 2 filter racks (one on each side) wired it up and mouted it high on the shop wall, cut a hole thru the shop wall to the outside and put a
slide open/close shutter vent over it and turned it on let her rip! Works
great, I had all the materials needed except the blower assembly but a
friend that owns a HVAC company gave me one he had from and old furnace for free! It pulls a lot of the finer dust away from the shop,
because I look at the filters and they are constantly getting dirty and need to be cleaned or replaced. Jim Heffner