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As someone who has posted a little information on dust collection, I was requested a few times to read the recent dust collection thread. Frankly, I have no interest in jumping into the current thread and trying to make one or another right. Rather than argue with opinions, here are some facts to ponder.
The reason to even be concerned is fine wood dust, the under 30 micron particles that are about 1/3 the diameter of a human hair and smaller, are known over time to cause a variety of serious health problems. Hand sanding and many machining operations produce these fine particles. They are so small and light they stay airborne for hours and rapidly spread to fill our shops and any connected air space, plus come home with us on our clothes. My doctor, a fellow woodworker and pulmonary specialist explained these fine particles slip right past our body’s natural defenses to lodge deeply in our tissues. In addition to the dust being an irritant, trees have natural chemical protections to keep them from being consumed when healthy. Like smoking, some will never show symptoms, but over time most woodworkers, their families, and others close to them develop sensitivities to these chemicals associated with wood dust. A few develop allergic reactions, asthma, and emphysema. Some even get polyps and cancer according to the National Institute of Health. One of every fourteen professional woodworkers is forced into disability retirement due to wood related serious respiratory problems according to an Australian health regulatory agency.
In spite of a good dust mask, nice air cleaner, and expensive dust collector that I used regularly, my doctor took my tools away from me due to respiratory problems. That could not happen to me! I was a “cool” engineer and had long taken excellent care of myself. And yes I have three engineering degrees with 35 years professional experience and 29 years of part-time teaching university engineering at UC and CSU. When my tools went, I got real serious with my research and quickly learned most of the protections I bought actually made matters far worse. My doctor, a fellow woodworker and pulmonary specialist explained my dust collector, air cleaner, down draft table, and even my shop vacuums were little more than dust pumps because their filters were far too open. Wearing my mask helped but I took it off long before the four to six hours it took my fairly high powered air filter (rated at 8 full air changes for my shop an hour) got rid of that fine, most harmful dust.
There are a few properties of this fine dust and air movement that I had to understand for this all to make sense. You can learn the same with a simple experiment. Get a couple of soda straws and a balloon filled with air. You suck and let a six-year old blow. See who can control the movement of that balloon. With at least double the lung capacity, you have zero chance of maintaining control. The reason for this is sucking basically pulls air in from roughly all directions while blowing sends a directed stream of air. Unless you take in a big enough bite or sphere of air, that balloon is going to be moved by any air current. The same occurs with the fine dust that we make from hand sanding, machine sanding, and from most of our higher speed cutters. Almost any air blowing from blades, bits, cutters, belts, motor fans, etc. moves that fine dust quickly away from the tool. Once it escapes the immediate area of the dust hood, it quickly spreads to fill the air in your shop and any connected areas such as your home. It stays airborne as long as you are running your tools, fans, blowers, etc.
Sadly, in our unregulated industry only the most ethical vendors provide fine dust bags that will actually filter the fine dust. Our truth in advertising laws let a vendor claim any filtering level they want by simply allowing the filter to get more and more “caked” until it no longer passes air. The key is they never say what airflow comes with that level of filtering as would be required with a filter that has been independently tested by an ASHRAE certified testing lab.
In addition, most hobbyist tool manufacturers focus on older chip collecting technology that does a poor job of fine dust collection. Few of our machines are really well designed in terms of keeping the dust captivated and then released into a dust hood. Instead, the primary stream of particles gets directed toward a single collection point with much of the fine stuff being blown everywhere. Many good alternative hood designs are shared on my cyclone and dust collection research web pages.
We need enough CFM at each machine to capture the fine dust at the source instead of cycling into our shop air and our lungs before finally being pulled out by an air cleaner. American Air Filter is considered one of the best names in industrial air quality and they produce the CFM tables that many air engineers use to design systems that meet our somewhat lax Federal air quality standards. They and my pulmonary doctors agree that capturing the dust after the fact in an air cleaner is better than nothing, but much more unhealthy than capturing the dust at the source. As you can see from this table, anything less than about 800 CFM to our larger hobbyist woodworking machines will not get the job done in terms of collecting the fine dust.
Air, just like water, is significantly restrained by the size of the pipe it flows through. Pressures from typical hobbyist dust collectors will move about 400 CFM through a 4″ diameter pipe, 600 CFM through a 5″ pipe, and the over 800 CFM in 6″ pipe as needed at our larger machines to get the fine dust. Yes, 4″ and sometimes even 2.5″ pipe works fine for many, but that sized pipe does not move the volumes proven as needed to consistently pick up the fine dust. Because air will compress around a small obstruction, you can go to your larger machines with a 6″ line then use a tapered 4″ adapter right at your machine and not lose too much CFM. All who make this upgrade find an incredible positive difference in how much better their systems work, and most wonder why that is not already an industry standard.
Terry Hatfield suffered continuing dust problems that affected his and his daughter’s respiratory health, so he reluctantly upgraded his Grizzly 1029 2 hp dust collector to 6″ duct. The results worked so well he put larger adapters on his machines, then followed my plans to build a cyclone. With a friend in the sheet metal business, Terry was so excited by the result and how much cleaner it make his shop (click here for his shop tour) Terry made metal kits available to fellow hobbyists (see Dust Elmiminator – click here for details).
Moving 800 CFM at your machines requires a big enough blower that can also overcome the considerable resistance from ducting, filters, hoods, and separators (calculate the resistance in your shop using the static calculator on my site). The computed static pressure resistance for your shop combined with the AAF airflow table for your larger machines (800 CFM for most hobbyists) will let you use a good fan table to quickly decide how much blower is needed for your shop.
For those who just want a general idea, small 1 car garage sized shops average a resistance of about 4.5″ of water column pressure, 2 car garage sized shops about 6.5″, and over 8.5″ for larger shops. Knowing that most dust collector blowers use the same kinds of fan and the same type of 3450 rotations per minute motors, a fan table can also quickly show what size ducting you need, what sized impeller, how many horsepower motor, and more.
Put all this together, and most end up needing a 2 hp blower with 6″ ducting and fine cartridge filters. Unfortunately, to protect those filters from being damaged most “trashcan” separators will not work, because the 6″ ducting allows so much air to move, it simply scours the cans of all but the largest chunks. That pretty much leaves either buying a nice commercial unit or stepping up to a cyclone separator. To drive a cyclone well you need enough motor and blower. It is pretty obvious that to really do the job most need a 3 hp blower. The below table show actual measurements from different real blowers used on the same cyclone.
My web pages provide a free plan for a very efficient cyclone design, free plans for both an airfoil and a budget good blower that you can build for about the same cost as a better dust collector, a high efficiency airfoil impeller, reviews of current cyclones, information on ducting and hoods, sources for the most affordable quality motors I could find, and the same for filters. I put up these web pages while off work with my own dust caused lung problems as a way for others to avoid my same mistakes. Please enjoy and work in a healthy safe shop that you keep that way.
bill
Edited 4/15/2003 5:36:45 PM ET by bill pentz
Replies
Thanks for your post, it was nicely written and informative; but I couldn't let this slip:
<quote>
Sadly, in our unregulated industry only the most ethical vendors provide fine dust bags that will actually filter the fine dust. Our truth in advertising laws let a vendor claim any filtering level they want by simply allowing the filter to get more and more "caked" until it no longer passes air. The key is they never say what airflow comes with that level of filtering as would be required with a filter that has been independently tested by an ASHRA certified testing lab.
<end quote>
One of the reasons I love ww is that I don't have to put up with the regulations and the handholding we get every day in life. If I want to make something beautiful, I can, and I can claim sole responsibility for it. If I cut off a finger doing it, and I can claim sole responsibility for that too. But the last thing we need is more government regulation and protection in our lives. If we want to protect ourselves, we need to inform ourselves through reading posts like yours, and taking personal responsibility for protecting OUR OWN lungs. We can't do that through regulation, because blind regulation can be just as dangerous, as well as uselessly restrictive. If I want to buy a cheap dust collector in favor of cost savings, then that will be on me. Any problems I have because of it will be on me too. Even if the vendor lied to me and told me it would be safe; then it would be on me for believing him.
Please don't push for any more regulation than we already have in our lives.
Tom
ps, sorry for the knee-jerk reaction to this one.
Tom, I believe his frustration is with the fact that your 1 micron filter bag may or may not be 1 micron as claimed and the company that produced it has no obligation to proove their claims. In essence your 1 micron bag may just be an over priced 30 micron bag. That is a sentimate I share. I don't like the govt in my workshop, but I sure want to get what I'm paying for especially when it's labelled.
I am by no means interested in more government regulation but there should be a requirement for truth in advertising. This is a problem in many aspects of this field from filter bags, cfm ratings and fan curves, to finishes and horspower ratings. We should be able to make educated decisions about what we are buying but there is so much leeway in what advertising claims manufacturers can make about their products that those decisions become much more difficult.Tom
Tom,
Not going at all toward government oversight. You made that leap after seeing some initials.
ASHRAE stands for <A href="http://xp20.ashrae.org/" target="_new">American Society of Heating, Rerigerating, and Air-Conditioning Engineers, Inc.</a> It is an international membership organization of engineers who create the worlds we live in, not a government organization.
When it comes to protecting the health of my family and myself, I insist on real test values verified by a standardized testing procedure instead of made up garbage.
In fact, the whole point of my discussion is the stuff being sold to hobbyists including our tools, their hoods, our ducting, our dust collections, and sadly even some of our air filters just make matters far worse.
bill
Bill,
You'll have to forgive me. As some one with libertarian leanings, and a strong knee-jerk reaction towards anything regulation, I become something more of a tourette's patient when the right buttons are pushed. I looked at your site, and you look like your main goal is to educate fellow woodworkers, which is to be applauded. I won't apologize for what I said, but I will apologize for directing it at you-Oh, and yes, ASHRAE did throw me a little. Thanks for clarifying. TMA! (Too Many Acronyms!)
Tom
BigCountry,
Thanks.. I do know the feeling about too much government and others telling me how I should live my life. *smile*
bill
Taking my engineering hat off ...
"One of every fourteen professional woodworkers is forced into disability retirement due to wood related serious respiratory problems according to an Australian health regulatory agency." I don't know the disability standard there. I don't know which problems are due to finishing fumes and other issues. I don't know how the dust levels there compare to home shops.
"under 30 micron particles" spans a wide range of particle sizes. In fact, some of these particles are easily cleaned from the lungs some are not. I don't know what percent of the particles from these various machines are dangerous or the level at which they become dangerous. I don't even know how much of the dust from my drum sander is of dangerous size.
I have wood dust, epoxy, varnishes, solvents in my shop. I don't know what concentrations of these products pose an equal hazard to me.
Finally, you provide no estimate of change in health problems based on using a good dust collector relative to a poor dust collector.
Putting my engineering hat back on ...
It is irresponsible to slander a whole industry in the manner you do.
If you can and do answer the "I don't know"s I have listed, I appologize to you and will preach your view of dust control.
George,I'm just another woodworker with a few degrees, lots of real world experience, and strong motivation because my arrogance and lack of real information took away my tools and landed me on an oxygen hose. This whole wood dust issue is not a game. It is serious business. Frankly, I could buy a new Felder every few months for what my insurance company and I currently spend on my medical care. I posted to provide some solid facts because others complained you were using your credentials to attempt to sway the uninformed to not take appropriate protections. You say, "It is irresponsible to slander a whole industry in the manner you do." It is not slander to openly say that many hobbyist dust collector makers advertising claims for dust collector horsepower, CFM, and filtering have nothing to do with real working levels. Using the rules by which this industry operates, I can legally try to sell my car saying it gets 92 miles per gallon, because I can prove it coasting down a mountain and reading the MPG gauge. These similar misleading claims harm fellow woodworkers with equipment that makes their shops worse than if they did nothing. If you find factual fault with what I have done or said, I will immediately make repair. Many leading air engineering firms in the industrial and hobbyist world contributed to my web pages and constantly provide advice and direction that I accept most willingly. Because I keep trying to share information, I do make mistakes. I also make repair as quickly as possible upon discovering a problem or misunderstanding, and welcome feedback to improve my efforts. Meanwhile, I offer for free plans to build a very efficient and inexpensive hobbyist cyclone and blower that costs less than most 2 hp dust collectors. Accompanying my plans that over two hundred people have built successfully, you will find my efforts to share information on my Cyclone and Dust Collection Research pages.If you are uncomfortable with your lack of knowledge on the potential immediate and long term negative effects of fine wood dust and its ability to go right past our natural protections, then you should do your own research. I would suggest starting with OSHA on Wood Dust and going from there look at my Links Page. I only echo the OSHA, NIOSH, and AMA recommendations to woodworkers to capture the fine dust at its source and use ample filtering to keep it from exposing you and yours to this respiratory hazard. I likewise, only echo the industry standard recommendations for required airflow, piping sizes, and filtering needed to meet the rather lax Federal indoor air quality standards that are seriously being challenged by various woodworker unions as far too lax. I likewise relay my pulmonary specialist who adamantly rejects the idea of exposing yourself and others to this fine dust expecting an air cleaner to get rid of it eventually. If you care, I suggest you spend some serious time reading over my web pages. There are many links to the experts in this field and considerable practical advice for affordable solutions.I only try to provide information that is well backed up and solid, so woodworkers can make more informed decisions about protecting themselves. I wish I had this information available thirty years ago. I do my best to honestly answer questions and provide help.bill
Bill,
Thanks for your informative post on the hazards of wood dust. I too am an engineer, retired 7 years ago, and now spend most of my time in the shop. I share your concerns about the health hazards many of us encounter while working in a dust laden atomosphere, and am in the process of ameliorating the situation in my shop. The information and links you have provided are an invaluable resource. Thanks.
Jack Lindsey
Thanks Jack. Let me know if I can help with questions.
bill
The following statement you made is slander (I guess libel but ...)
"These similar misleading claims harm fellow woodworkers with equipment that makes their shops worse than if they did nothing."
Show me a definition of harmful dust level.
Show me a side by side comparision of two shops doing the smae work one with a dust collector and one without where ...
------
I understand your desire to blame faulty dust collection equipment on your health problems.
Have you sued the dust collection people and had a judgment in your favor? I suppose not.
-----
I use a 1hp dust collector in my 13x26 material processing shop. I often use a 18" drum sander for 6 hours a day. I don't even need a
shower when I leave the shop.
George,You continue to make your arguments personal and emotional without taking the time to think things through.The following statement you made is slander (I guess libel but ...) "These similar misleading claims harm fellow woodworkers with equipment that makes their shops worse than if they did nothing." Use of too small of ducting as you advocate, too small of a blower as you advocate, and retroactive filtering relying on an air cleaner to gather the dust after it has filled your shop is unhealthy. This represents fact sustained by the leading experts in the field, not slander or libel.Show me a definition of harmful dust level. I did with the OSHA and multiple other reference sites.Show me a side by side comparision of two shops doing the smae work one with a dust collector and one without where ... Digging out more information for you when you failed to read what I already provided does not seem fruitful. The real issue here is those who use inappropriately configured ducting, hoods, blowers, and filters will fill their shops and possibly their homes with a much higher level of fine dust that we know over time can affect them and those close to them adversely.------ I understand your desire to blame faulty dust collection equipment on your health problems. Have you sued the dust collection people and had a judgment in your favor? I suppose not. This is none of your business.----- I use a 1hp dust collector in my 13x26 material processing shop. I often use a 18" drum sander for 6 hours a day. I don't even need a shower when I leave the shop. If you check the AAF air table I provided, your sander should have enough airflow from a 1 hp dust collector that it will not create a dust problem.bill
Bill,
Just wanted to take this moment to thank you for all the info you have posted. I have been reading your material over the years and have placed dust control number 1 on my list with price second. I like your straight forwardness get to the point approach. My kids are now with me in the shop and they are all aware of the potential hazards of dust created while working. The first thing they do when we start working together is ..."Dad, we need our ear protection and dust masks...make sure we turn on the DC and air filtration..."
You have a great site and I hope you continue to update the material to keep us informed of this important subject.
I enjoy woodworking and I also enjoy breathing. Thanks again for the work and the concern you have for your fellow woodworkers!
rrwood
RRWood,
Thank you!
bill
Consumer protection and worker safety do sometimes cross the line of individual rights. However, in the United States corporations receive special consideration, and need to be more responsible for what they do and say.
Dust collectors are also dust distributors. I have used bag collectors ranging in size from a hand held belt sander with a bag, to a bag house. Every one of those bags was worthless. The bags collect the big stuff, and blow a lot of fine dust all over the place. Workers are further exposed to dust when they have to maintain or empty the bags.
In my shop, I have a blower with a 12" inlet, powered by an old 5 hp motor. Using minimum 6" diameter pipes, this collector seems to get most of the dust. I also ducted the pipes as close as possible to the dust sources. The dust goes out to a small trailer. The exhaust and fine dust blows out into the field. I use the sawdust as fill on a woods road. I figure it returns material to the forest. The coarser shavings, like from the shaper, make good cat litter. I compost this with leaves, and use it on non-food plants. (Cats pass parasite eggs into their waste, and I can't put this on food crops.)
Because I have no neighbors, the exhaust dust isn't bothering anyone else. In the winter, I turn up the heat. My lungs are worth the money I spend on heat.
For the fine dust, I have a shop vac outside, with a Sears shop vac cannister as a first stage. Through a few 2 1/2" hoses, the shop vac catches the dust off the top of the table saw blade, the router, sanders, and I use it to vaccum the floor. With the shop vac outdoors, it doesn't make as much noise inside, so I can run it for hours. I am going to put a quiet motor on it, like a little drill press motor, and drive the impellers with a belt. The shop vac dust gets dumped in the compost pile.
The state of the art in small shop dust collection is not static. We have a lot of room for improvement. There are hazards posed, and solutions available, that we have yet to see.
Sash Guy,
Well said and well done. You are in an ideal situation with putting that dust outside and using plenty of motor and blower to make sure it gets there. Yes, it does cost a little more fuel in the winter, but as you say well worth it.
You are also right on with your comments, "The state of the art in small shop dust collection is not static. We have a lot of room for improvement. There are hazards posed, and solutions available, that we have yet to see." From here it is up to each of us to learn the facts and implement appropriate protections, or just live with the potential results.
bill
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