Re: < 20 micron bags and just wear a dust mask

and then supplement that w/ a couple $10 air filter boxes made from scrap squirrel-cage fans?
On Sun, 24 Aug 2003 06:51:01 GMT, nospam snipped-for-privacy@mesanetworks.net (coloradotrout) wrote:

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On Sun, 24 Aug 2003 06:51:01 GMT, nospam snipped-for-privacy@mesanetworks.net (coloradotrout) Crawled out of the shop and said. . .:

agreed, and also agreed to your follow up. personably, i am not really all that worried about the finer dust, most would argue its the smallest particles that do the most harm, but i am of the opinion that i get more nasty crap from a southbound greyhound than i get in my shop. when i woodwork, i am there to have fun, create something from wood, and to leave most of my troubles on the outside of my shop door.
JM2CW Traves
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Hi CT, I believe the flaw in your argument arises from the fact that for most people their dust Masks, while offering some protection, do not work as well as they think they do. And most health concerns are caused by the smaller particles. A dust mask (like those worn by Drs. in surgery) are worn to protect the patient from the Dr's spital and nasal secretion and not to protect the Dr. These are often the same type as we WWs ware. The seal between the mask and your face is not adequate to stop small particles from being inhaled when you breath. Even with a proper (and fitted) respirator the seal is only effective if you are clean shaven (for some guys every four hours). As your face sweats and breathing is impaired somewhat from wearing it, people tend to wear them less and less. That is why every attempt should be made to keep the dust from becoming airborne in the first place. Now, if you are going to go with a battery operated powered respirator then that can be a different story. Cheers, JG
coloradotrout wrote:

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I don't like wearing the mask either. I have a 3M flavor that has 2 elastic straps. A few years back it was suppose to be one of the better disposable ones for wood dust. It's not a cartridge unit, though I have one of those, but it's too heavy and annoying (have used it for spraying).
I don't see how any of the bag units can be perfect. Even if they say 0.3 micron, is that realistic? I'd guess it's more like saying the bag (in the ideal situation) can get 0.3 microns. In reality, though, it's probably no wheres close. I'd like to see published specs on the canister units. And I just can't fork out 800+ for a stationary cyclone.
Getting a 5, 3, or 0.3 micron bags these days is pretty inexpensive, so that's where I'm headed. But if the small stuff is the worst, I'm not very confident any of the current solutions are as effective as one might initially believe. Capturing the dust at the source would seem nearly impossible for most tools, e.g. contractors TS, SCMS. Jointers, planers, and DPs would seen to produce mostly shavings, that would be of less concern.
For the air filter unit, I was thinking of putting in 2-3 Filtrete filters (used furnace , then vacuumed).The filters would seem to be the ONLY way to capture airborne dust that has eluded the collector.
I guess an interesting question.. is how much of woodworking dust is < 2 microns?
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How much is <2microns? That is a good question or at least one that I researched a bit when I use to work in the hygiene field. As you state, planers, jointers and DPs create very few small particles. Sanders create a lot, with a TS somewhere in the middle. This is one consideration however you must also consider your duration of exposure and the type of dust you are exposed to. As I have spent more and more time in the shop over the last few years I have come to realize what an academic exercise this (exposure to small pcles) is. For a shop like mine where our tasks change everyday there are so many variables. What I have noticed is that my filter ( IIRC 1 micron) in my cyclone starts to clog quite quickly (within an hour) when I use it for my drum sander but will run with little impedance for weeks if I run only the other tools. So now when I use a hand sander, not hooked to the cyclone, I wear a proper respirator if its a long job and a dust mask for the short jobs. JG
coloradotrout wrote:

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what cyclone are you using? one of the internal filter oneida?
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Hi Steve, Yes, it is the older 1.5 hp internal filter Oneida. Cheers, JG
Steve Knight wrote:

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Steve is a big proponent of felt bags. With multiple paths provided by the felt structure, the air pressure is low in any given path, allowing particles to precipitate or "catch" in the fibers. With higher airflow/lower backpressure in the bag, even the non-bag components don't leak as much - lower airflow - so it's a win/win.
That said, the principle behind felting is to take a bunch of fibers and intertwine/compact them. This is also done inside any bag by accumulation of sawdust "cake" which first filters finely, then ultimately clogs. You can also reach this state in felt bags, so keep an eye on them. They are, after all, fibers. If you have a bag which is not passing visible dust, and I mean visible in a concentrated light beam, you're fine. Until you reach that stage, wear a mask. When you clean a conventional bag, don't shake the cake, and you can return to that fine filtration stage that much earlier.
Now, as proponents of felt point out, this method does produce higher backpressure, and therefore is less efficient at pickup, though efficient at filtering. My little 3/4 horse keeps up with the planer, pulls nails and such off the floor, so I guess it's enough in both capacity and vacuum for my needs. Final point. You are equipped with an exceptionally great system for accumulating and rejecting particulate matter in your nasopharynx and trachea - mucous and cilia. If you can't color a tissue, you're doing fine, no matter what the naysayers try to make you believe.

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this is the wrong thinking. the dust cake does not shake off very well. too much cake and you have back pressure and the back pressure forces fine dust out of the bag. the bag will filter the best when it impeades the airflow the least. this is why a bigger bag is always better. the more often the bag is shaken the better. the commercial bag houses have auto shakers to keep the bags clean. Once I found out about this I got better use and airflow from my big felt bag.
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If it were true, I would believe you, Steve. But, as it is not, I'll go with what I said.
The big people use felt bags, as you said, and as I said or implied, felt bags need to be shaken or cleaned lest they fill from inside out. Non-felt bags operate on the pure filtration principle, and are therefore more efficient at filtering when the gap size between medium is smaller..
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I'm kinda following..
So any suggestions for bags? The Grizzly 0.3 micron? or 3.0 micron? or other?
http://www.grizzly.com/products/items-list.cfm?key0000&sort=price
Why would ANYONE buy the 3.0 micron for $20 when the 0.3 micron is the SAME PRICE?
The envelope style? Mmmm.. how about I put a solid plastic bag (or rig a canister to the bottom side, and then add TWO bags to the top side -- even if it rubs up agains the ceiling?
Do the seperator lids really make a big difference? Logically.. is seems like they would --get the chunks out -- spare the blade -- and facilitate mulching the garden!!!
Thanks much!
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On Tue, 26 Aug 2003 07:25:08 GMT, nospam snipped-for-privacy@mesanetworks.net (coloradotrout) wrote:

it's not really .3 microns. you need a paper cartridge filter if you want to go down that low. but it is better then regular bag. but still way too small.

they just make it easier to dump the can. at the cost of airflow a fair amount of it.
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On Tue, 26 Aug 2003 15:41:10 GMT, Steve Knight

One could always stitch two top bags together to form a Y to recoup the airflow. A slim piece of trim wood over the holder would keep their arms up. Not a problem.
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might be talking 2 things here
the seperator lid would just be one of those trash can lids piped in ahead of the DC
if i put a plastic bag or canister as my bottom bag of the DC, then I'd have to add surface area somehow.. presumably. I thought i could do that by sewing 2 bags tog. for the top bag. Probably would hit the ceiling, but w/ those envelope style bags, seems like it would be pretty easy to do.
how big a "chunk" can make it through the fan blade? seems like a 1x1x1 could do a lot of damage.
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O

easier to buy a pre made bag from www.americanfabricfilter.com they can make the bag any shape you want.

well you do need to be careful of the big stuff. but it's not hard to keep out of the system.
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