Cyclone and Dust Collection Research


Welcome to the updated Cyclone and Dust Collection Research web pages.
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My DC History

  1. My Dust Collection History

    My early woodworking and medical engineering work eventually taught me to minimize fine dust exposure, especially when working toxic woods.

    Unlike most my dust collection started with my getting rid of the dust cloud that filled our family home construction cabinet shop. My father apprenticed to a fine woodworker who specialized in cabinets and trim for very expensive homes. When he opened his own constuction firm after retiring from the Air Force, he was not happy with the stock cabinets we could buy, so he opened up his own cabinet making operation. Although he preferred to do his woodworking with hand tools, he equipped this cabinet operation with the best in commercial quality tools. His cabinet shop soon became the local supplier of choice for high-end cabinets. It also became such a dusty cave that all who worked there had respiratory problems. After two commercial dust collectors failed to help, my homework led to his having the top commercial dust collection firm install a large cyclone based dust collection system that vented outside. After working there for a few years I moved out and put myself through college building fine cabinets and building homes. My college roommate talked me into helping him start a furniture shop that made massive redwood tables and chairs in our garage. The dust was so bad we had to live in NIOSH certified 3M dual cartridge respirator masks plus run a strong fan blowing the dust away from us outside. When we moved to a commercial space I had the top vendor design and install a good dust collection system. After taking a break to serve in the Vietnam War, I went to work for CSU Sacramento teaching digital electronics and programming. Because of my background in woodworking, our dean had me specify and oversee the installation of a cyclone based dust collection system that vented outside for our university wood shop.

    At home my dust collection went through the normal foolish progression where all worked poorly. I started with a small shop vacuum, a larger vacuum, a ShopSmith small dust collector, and a larger dust collector. When we upgraded the family cabinet shop to a commercial dust collection system I claimed a 2 hp Cincinnati Fan dust collector made up of a big blower that sat on a roll around 55 gallon drum. Emptying that way too heavy 55 gallon drum when it was full proved a nightmare, so I bought a used second identical unit which let me go twice as long.

    My shops changed dramatically and so did my dust collection. When in a carport I had to use the dust collector and fans. When my shop moved to a garage I was able to put in 4" ducting to all of my tools that had semi-permanent places. I then moved to home with a separate large shop. That shop had a four foot crawl space under the floor, so I went from overhead ducting to under the floor ducting. As I kept adding and changing equipment that floor soon looked like a prairie dog village with more patches than floor I so often had to relocate my dust collection. I then got super busy at work and ended up living in a condo with no place for my woodworking, so all lived in storage. I then bought another home and all went into the garage piled around the perimeter because our cars had to be parked inside. Woodwork was a real pain as all had to be cleared off, then wheeled out, setup, then put back every time I wanted to do anything. This got ever more difficult as more and more tools and dust collection pieces found their way into my shop.

    We loved that upscale lifestyle so much that when our family grew we upgraded to a much larger home in the same neighborhood that had an oversized three-car garage that let me dedicate one whole garage bay to my woodworking. This left me a permanent place to put my dust collector, large air compressor and largest tools, but I still needed most on wheels. My projects required me to move the two cars out, wheel the tools in place, then after put all back. I also was dragging a very long flexible dust collection hose from my dust collector and having to change it to each different tool I used. I installed 4" PVC ducting all over with blast gates which make the dust collection far easier. My family gave me a two foot square down draft table that I mounted into a roll-around table that matched the height of my tools so it could double helping with in and out feed functions. This down draft table helped lots when I used my hand held orbital sander, but was too small without enough airflow for most projects, plus its metal grate scratched my work. That inspired me to build a bigger down draft table of my own design that doubled as an auxiliary workbench as well as in and out feed table. I also made a collection hood from a large HVAC register duct that connected to a 6" hose mounted on a heavy microphone stand that could adjust to suck next to my work. That hood made all the difference when using my lathe.

    Tired of the dust that settled overnight ruining finishes, I upgraded both of my Cincinnati Fan dust collectors and my ShopSmith Dust collector with large polyester fine filter bags. These bags clogged constantly because woodworking makes too much fine filter clogging dust. That inspired me to buy a new dust collector that was supposed to eliminate the clogging problem and still provide good fine filtering. It did not work.

    Worse, my finishes were still getting ruined from overnight dust settling, so I built an air cleaner using an old water cooler fitted with fine HVAC filters. Although it moved a lot of air, it was noisy, took a huge amount of room and worked poorly, so I replaced it with an expensive ceiling mounted air cleaner. Later I learned the main problem with my homebuilt air cleaner is it did not have a strongly directed stream of air that forced all the shop air to get stirred. Without that stirring our air cleaners simply clean the same air over and over.

    The replacement commercial ceiling mounted air cleaner did a much better job protecting my finishes, but my new particle counter showed just like the so called fine filters on my shop vacuums and dust collectors my air cleaner filter passed the fine dust right through so it also was a dust pump that stirred up and kept the unhealthiest fine invisible dust circulating. I got rid of that air cleaner after my particle counter found a much better solution. It showed a fan that blew out the side door with the main door cracked a few inches did a much better job than my air cleaner. The fan much more quickly got rid of both the larger airborne particles that ruin finishes and the buildup of fine dust that ruins our lungs. My particle counter showed to amply clear my shop air I had to let the fan run for a half hour after I stopped making dust. The particle counter also showed whenever I made dust including working with hand tools like chisels and planes that made no visible sawdust, I still made so much fine invisible dust I needed to wear my NIOSH approved 3M dual cartridge respirator mask and use the fan.

  2. My Early Cyclone History
    1. Homemade Cyclones

      ShopNotes: ShopNotes Cyclone My area has many local sawmills and the cost to buy my lumber from them rough cut is about half the price for finished lumber, so I did my own planning and surface sanding. This saved lots of money on the mostly red oak and walnut projects I liked to make, but left me feeling like I spent more time emptying the too heavy 55-gallon drums under my dust collectors than doing woodworking. After reading that a cyclone would separate off almost all of the sawdust and chips, preferably into a smaller manageable 30 gallon container, I built my first cyclone in 1994 from the August Home Publishing 7/1994 ShopNotes magazine plans. I powered it with one of my identical 2 hp Cincinnati Fan dust collector blowers. Although this cyclone made emptying the chips easier, it only moved about half of the air as did that blower when used in dust collection mode. Worse, the cyclone clogged constantly especially when I used my big planner.

      This made me a little crazy as I get obsessive about figuring out why something works poorly and what needs to be done to make repair. My research showed the person who designed this cyclone did not do their homework. This cyclone was based on a 1963 public domain cyclone design for wood dust collection given out for free by the New York State Department of Labor. Instead of following that 1963 design someone severely changed the dust chute that connects to the dust bin down from 6" to only 4" so it would work with the 4" ducting that most small shop stationary tools use. They also shortened the cone to force fit this unit under the typical eight foot tall ceiling that most U.S. garages share. I then found a spreadsheet based on work done at Texas universities that lets us model all seven different classes of cyclones. This cyclone turned out to be the standard cyclone used to separate cotton from dirt and sand. It actually was engineered to have the maximum possible internal turbulence to break the sand and dirt from the cotton tufts, then drop the heavy stuff and blow all the light stuff right through. When used for woodworking it is about 99% effective by weight at separating off the heavier sawdust and chips passing only airborne dust and strange shaped pieces that act like sails and get caught in the internal airflows. Airborne wood dust by definition consists of particles sized under 30-microns that vanish with no visible trace when vented outside. OSHA weighed a large amount of wood before and after processing. They found airborne dust on average makes up about 5% of the weight of woodworking created dust and chips. Most large facilities that use woodworking cyclones use a 30-micron filter to capture the strange shaped pieces then blow that remaining 5% of the airborne dust by weight away outside. Airborne dust quickly breaks down as soon as it gets wet. When I modeled this modified design, the spreadsheet showed this cyclone reversed the airflow inside too early. That kept the chips from dropping and caused the cone to plug. I redesigned and replaced the bad cone and with a cone properly angled with the right dust chute opening so it works. This fixed the clogging problem, but the cyclone still only sucked about half as well as my identical powered dust collector.

      Wood Magazine: Wood Magazine Cyclone Frustrated at how little air my ShopNotes cyclone moved and how poorly it separated, I built a new cyclone based on the Wood Magazine cyclone plans. It turned out that plan created an almost identical cyclone to the ShopNotes unit, so it had identical separation and plugging problems, plus had even more problems. I remade the cone just as I did for my ShopNotes cyclone. That fixed the plugging. A bigger problem was they recommended far too light weight metal, so every time I turned on my 2 hp commercial dust collector blower, my cyclone flexed so much it kept breaking open its side and cone joints. Any leak immediately killed the cyclone's ability to separate and filled my filter with sawdust. I made a series of reinforcement rings for the main cylinder and cone that limited the flexing and saved the joints. It still sounded terrible from the heavy flexing. Airflow and collection, just like the prior cyclone remained terrible. My same blower moved far more air when it was used to power a dust collector. That poor airflow provided poor collection and the cyclone separated so poorly it left me to constantly clean the big fine filter cartridge that was an upgrade from the ShopNotes filter box.

      Instead of getting good advice that would help solve these problems, all the Internet woodworking forums were filled with ugly dust collection fights. Regardless of using a home built or purchased cyclone, it seemed all who did little to no woodworking loved their cyclones and those of us who made a lot of dust and chips hated ours. Both camps defended their positions to the death. All serious users had problems with poor airflow, bad collection, cone plugging, and filter cleaning. I started one of the first woodworking forums and turned that forum over to a friend when I got tired of babysitting adults. I refused to get involved in these big wars. Those who complained loudly along with many very knowledgeable scientists and engineers who tried to educate us about why we were having problems all got permanently banned from many of the larger Internet woodworking forums.

      Neutral Vane: Neutral Vane I finally stumbled on a fellow who was called the "Dust Hound" on many forums. His name is Jim Halbert and he is a very bright successful engineer. Jim and I shared similar frustration over so many false vendor performance claims. The fights on the various forums were getting so bad that I laid low while Jim got hammered almost daily. Jim shared a fix he came up with that significantly helped airflow. He said his neighbor and fellow woodworking friend John Dillbeck spotted an idea on an obscure cyclone article. Jim said he saw the same article but dismissed it as nonsense. John tried it on his Wood Magazine cyclone and it worked, so he showed Jim. Jim decided it was too involved with boxing, ducting etc, so he came up with a much simpler solution. He just stuck a pipe inside the inlet on his cyclone then moved it in and out until his motor registered maximum amps. A blower motor does the most work and pulls the most amps when it moves the most air. His solution worked just as good as that complex solution. What that inlet pipe extension adjustment does is reduce turbulence by keeping the incoming air from crashing into the air already spinning inside the cyclone. Jim shared on the Internet and it got mislabeled as a "neutral vane" and it took off with almost all making this change to their homemade and purchased small shop cyclones. Soon after the leading small shop cyclone vendor not only added neutral vanes to their cyclone, they also claimed credit for Jim's work and included it in one of their patents without properly giving credit to Jim. I made his recommended change and I bought and installed a set of the big Donaldson-Torit cartridge filters with a cleanout. These changes improved the airflow by a full one third. That still left my cyclone working only about three quarters as well as the dust collector the same blower previously powered.

      More: Determined to make this work I kept trying. Realizing that the problem was our traditional cyclones had way too much internal turbulence, I then kept tweaking to reduce that internal turbulence. I ended up changing the inlet size, added an air directing ring to further reduce turbulence, increased the outlet size, changed the cone angle, and increased the dust chute size. The result worked much better without the prior plugging problems, but separation remained little better than my trashcan separator lid. To get more airflow and better collection I bought and installed a new much larger commercial Cincinnati Fan blower with an oversized larger diameter impeller. I carefully checked with an amp meter that my most open ducting configuration did not make this blower move more air and pull more amps than my motor could handle. I documented all my changes on my Cyclone Modifications pages. Today almost every small shop vendor except for one now builds the revised cyclone design I documented. The one vendor who builds a different design came in dead last in a recent cyclone magazine separation test. All these changes made a huge difference in my cyclone and its collection, but I remained very unhappy still as collection was still not as good as the dust collector these cyclones replaced and separation remained so poor I still spent way too much time cleaning the fine filters which were quickly getting ruined by sharp chips.

    2. Small Shop Cyclone

      I tired of the dust collection mess. My too busy career barely left time each year to make some modest Christmas gifts. Even with all my dust collection efforts, my cyclone's poor airflow provided terrible collection making for frequent large messes to clean up. The terrible cyclone separation kept clogging my fine filters. I hated spending my limited time on dust collection instead of woodworking. The cyclone made terrible noises every time I turned it on from the metal flexing. I disliked the need to always wear my dual cartridge respirator mask and run a strong fan blowing the airborne dust my cyclone missed away outside. I hated that fan freezing me while building those gifts. I wanted to do woodworking, not mess around with dust collection.

      Top Rated: I really just wanted to buy a used smaller commercial cyclone, but was very frustrated as none were available locally that would fit in my garage based shop with its eight foot tall ceiling. That left me not knowing what to buy. I contacted the magazine top rated cyclone supplier and got from them a full quote including ducting design with all the parts detail, but was hesitant to pull the trigger. Most of those who bought these same top magazine rated cyclone systems swore by them, but I had been hearing some bad things as well. I decided to do more research. I grew up in a family that was the cabinet supplier of choice in our area plus we were well known for our custom homes. I knew lots of people who do woodworking and construction, so started calling around. I also asked my friend Jim Halbert if he knew anything about these cyclones. Jim said he owned one and it was excellent metal work on a junk design that worked worse than his home built upgraded Wood Magazine cyclone.

      I then got a call from an old friend who got his start in our cabinet shop when I was its manager. He said he contacted that same top magazine rated cyclone firm, was assured that their standard cyclone moved more than enough air for his two and sometimes three person shop with all working at the same time. They prepared a full quote for him including a detailed ducting design based on him sharing his shop size, tool locations, and all else needed to design the ducting. He bought the works including their recommended cyclone, all the ducting to plumb his pretty good sized shop, and even a batch of their recommended upgraded fine cartridge filters. My friend said he and his coworkers spent nearly a month installing that cyclone. Most of that time was spent working through all the ducting problems created by the often just plain wrong ducting design and parts that firm sent.

      When they finally got it all running, they were devastated to find this system was near useless. It came with 1", 1.25" and 2.25" down drops for their many electric and pneumatic hand held tools, but provided almost no collection for any of these smaller ported tools. He had to go back to using his shop vacuums on those smaller ported tools. Almost all of his machines had the typical 4" sized dust collection ports and hood attachments, but this cyclone would not even provide good collection when pulling from just one of these tools working at a time.

      He spent a lot of money on that system and asked the vendor for help they refused to give. They instead shuffled him from one person to another. He talked to their chief engineer and said that fellow not understand either woodworking or dust collection. He finally ended up in a shouting match with the firm's president. He said their president flagrantly lied, blamed him for all the problems, and refused to honor the firm's written money back guarantee or warranty their products. In short, he got zero support from this firm.

      Meanwhile he had a business to run, deadlines to meet, and a lot of production getting severely backed up. He called Donaldson-Torit. Their engineers came in and had nothing but bad to say about this so called top rated system. They said it was illegal to put it inside because it was not certified as fire and explosion proof, but did not come set up to work as an outdoor unit. They said the filter was at least four times too small. They said the ducting design and components were the worst they had ever seen. Not only was the ducting poorly designed and sized, it was standard HVAC duct which is designed to move air in the opposite direction. This ducting created just about the same effect as putting on the shingles on a roof backward which causes the water to flow into the home instead of on top of the shingles, plus creates lots of extra resistance. They said the blower was less than one quarter the size needed for his shop and was so poorly made with a circular instead of spiral housing and their test meter showed it did not move one quarter the airflow the vendor advertised. They said the blower impeller was a badly cast aluminum mess where the supports were on the wrong side of the blades and that aluminum impellers are no longer recommended for dust collection because when hit by metal aluminum launches sparks just like a sparkler. They said that impeller was doubly bad news as it can slip off the motor shaft because it was inappropriately mounted with set screws instead of a compression arbor. Set screws should only be used on motors with horizontal shafts and never on vertical shafts. They were most upset about the cardboard dust bin and said it was a fire just waiting to happen. In short, they said nothing could be saved.

      My friend paid to have a new Donaldson-Torit dust collection system installed. Their technicians removed the prior system and put all the parts in his out building. He went back to work and struggled over what he should do with that prior system that was only a couple of months old and supposedly had a full year warrantee. He has too much integrity to sell it as he knew it was useless, but paid too much to just throw it away. He made me an incredible offer. He said I could have the whole system and if it worked for me just pay him whatever I wanted, but if it did not work, get rid of it. I ended up with exactly the same system that was specified for me with about twice the total ducting that my garage based shop could use.

      Installation: In September 1999 I installed that "best" magazine rated cyclone following the vendor designed and supplied ducting diagram for my shop and used the vendor recommended upgraded fine filter. I was very impressed with the quality of the metal work, but very unimpressed with the poorly designed blower, and poor quality ducting. The ducting design was horrid and required me to redo most of it because their design left off all kinds of required parts to implement their plan. I was more upset to find my local box store sold identical ducting components for half the prices my vendor charged. I was really upset to find the very expensive bin full sensor I bought separately was a standard Dwyer Instrument sensor that I could have bought from Dwyer for less than half of what I paid. It took me over a month of all my spare time to install that system. I finally got it running in early October 1999.

      Problems: That top rated cyclone ran but did not work! Unlike most I had the engineering background and contacts to do some very serious testing.

      • Bad Cyclone Design: This cyclone had all of the same problems my prior cyclones did before I upgraded them except the metal was heavy enough it did not deform when I turned on my blower. Just like my prior two cyclones it separated so poorly it quickly plugged my fine filter and its cone plugged every time I used my planner, my shaper or collected lots of chips. Careful measurement showed it was exactly the same cyclone except for a slightly larger center outlet tube that held its internal filter. In other words, I got the same problems as before on a cyclone I could not easily change to add my prior improvements. I later was told this vendor copied the ShopNotes cyclone, then sold copies of this design to all but one of the other small shop vendors who sold cyclones.

      • Bad Blower: The blower worked so poorly that I took it to the university and had our air engineering professor test it. He was appalled and said it was one of the worst blowers he had ever seen. He shared that blowers use a spiral to properly handle the increasing air created by a turning impeller, but this blower had a circle. That circular shape creates bad pressure waves that actually kill blower performance. He was stunned when he looked at the impeller. He found the vendor used a cast aluminum impeller held in place by a couple of set screws. He said the impeller will eventually slip right down the vertical motor shaft. When it does it will crash into the metal blower housing and ruin both the impeller, blower housing, and maybe even the motor. Worse, aluminum impellers were once recommended, but the National Fire Protection Association (NFPA) who writes the standards most communities use for their building and fire marshal inspections no longer recommends aluminum impellers. They found that when hit just right aluminum impellers launch white hot little bits of aluminum just like sparklers. Although most burn out quickly, if there is dust built up in our ducts this can create a nasty ducting fire. Today only steel and brass impellers are recommended for dust collection. Worse this cast impeller had the blade support molded into the wrong side of the impeller where it badly blocked airflow. His measurement showed instead of being the advertised over 1,200 CFM blower, it barely moved 349 CFM through the 4" duct my vendor ducting design used on all their larger down drops. His recommendation was to buy a good commercial blower and replace this one immediately.

      • Bad Airflow: The airflow testing showed my expensive magazine top rated cyclone moved less than half its advertized air volume and its actual flow was far less than my dust collector it replaced.

      • Poor Collection: Although the vendor promised in writing enough airflow to provide good fine dust collection from three large and one small tool working at once, its working airflow barely collected half as well as my home built cyclones when just collecting from a single tool.

      • Poor Separation: Particle testing showed that this expensive top rated cyclone separated no better than a $25 trashcan separator lid. This of course meant all of the fine dust separation was left up to the filters.

      • Bad Filter: The upgraded fine filter this vendor sold was a double sham. Although advertised as a better than 2-micron filter, when tested with calibrated test particles this filter freely passed 100% of the invisible 10-micron and smaller invisible dust particles known to cause the most health damage. This tiny cartridge that fit inside the cyclone outlet was way too small so not only plugged constantly, the heavy cleaning quickly ruined this cartridge. It took me longer to take apart the cyclone to clean this filter than it took to load the filter back up. Cleaning it left me and my shop covered in the fine dust I bought this system to avoid. Donaldson-Torit is the most respected and largest name in commercial dust collection and dust collection filters. Their wood dust collection engineering notes say our filters must be at least one square foot of area for every four cubic feet per minute of airflow and if we want our filters to not quickly get ruined from being over cleaned, we actually need one square foot of filter area for every two cubic feet per minute of airflow. With this filter loading, they typically get about three full time months of use out of their fine filters in typical woodworking facilities. This filter on a supposedly 1200 CFM machine needed to be no less than 300 square feet and should have been 600 square feet, but it was well under 100 square feet. With this filter at less than one sixth the recommended size it plugged roughly every twenty minutes of sanding or heavy dust production. My filter barely lasted a week before it was so broken down that a particle meter it had turned my cyclone into a dust pump that freely passed up to 30-micron airborne dust particles.

      • Bad Duct Design: Worse, this same vendor designed ducting was not even high school quality. I discovered my vendor used and still uses a free computer ducting design program designed for larger shops that do not use blast gates and instead collect from all machines running at the same time. Woodworking dust collection has been a requirement since the 1920s so is well understood. We know we need at least 3800 feet per minute (FPM) air speed to keep vertical ducts from plugging and need about 2800 FPM airspeed to keep horizontal runs from building up piles. Everyone knowledgeable about dust collection ducting design also knows that air at dust collection pressures is like water and will barely compress at all, so any small duct, rough duct, or even sharp angles will severely block our airflow. Dwyer instruments is the most respected name in airflow test instruments. They found just ten lengths of ducting sets the overall airflow at any given pressure. As a result any undersized tool port, overly restrictive tool hood, undersized duct or hose, or dirty filter will add enough resistance to all but kill the airflow we need for good collection. This also means dust collection blowers do not develop enough pressure to work with duct sized under about 3", yet my vendor designed and provided down drops sized 1", 1.25" and 2.25" to work with my smaller hand held tools. That explained why I got almost no collection and lots of clogging with these smaller tools. This is also why ducting sizing is carefully matched to support needed airflows and keep the overall speed up enough to ensure our hoods, tool ports, and ducting stays clear. The design program they used correctly makes graduated ducting so each branch and main can carry all the air from downstream. Unfortunately, with a system designed for a small shop it really needs all vertical runs to be the same size and the horizontal main run to be the same or a slightly larger size. With the horizontal main a little larger it reduces resistance so works better so long as the duct air speed stays high enough to keep the dust moving. Using this graduated ducting design program on a one machine at a time dust collection system created immediate problems with keeping the dust moving.

      • Duct Plugging: This system used tiny down drop ducts that that so restricted the airflow both the larger vertical ducting runs and larger main ducting run were left without the air volume or speed to keep the dust moving. The smaller down drops reduced the larger ducting air speed to under 50 FPM which is far short of the 2800 FPM needed to keep horizontal runs clear or the 3800 FPM needed to keep vertical runs from plugging. My vertical duct runs constantly plugged. Worse, this vendor ducting design had all the down drops go straight down from the main instead of coming out to the side then down as do well designed systems. The poor airflow simply rolled the sawdust and chips into the down drops filling them. When the blast gates were opened on these full down drops they either plugged or launched a huge pile of dust upward. They plugged so often I constantly had to clean out the ducting.

      • Duct Piles: This same terrible airflow created another bad problem in the horizontal mains. The mains never had enough air speed to stay clear unless at least three large down drops were open. As a result, most of the heavier dust and chips simply piled up in the larger horizontal duct runs then these piles grew in length into huge long piles. Dust piles in our ducts pose a very serious fire danger. Most don't realize but if you watch in a dark room our power saws, shapers and routers when working hardwood almost always generate sparks. Most sparks burn out immediately with the high airflow in our ducts. However, when the ducts are full of sawdust, these sparks can land in these piles then quickly get fanned into a disastrous ducting fire.

      • Blown Joints: These plugs and ducting piles also created a constant frustration because when airflow was restored so much material went shooting down the ducts it created lots of noise and hit the duct joints so hard they blew apart filling my shop with debris and dust.

      • Vendor Support: This cyclone proved so worthless when using my planner and big sander, that I had to go back to using my old dust collector. A lot of money was spent on this system that was promised to be fully warranted for a full year. It clearly did not collect well, plugged its cone constantly, plugged its filter every twenty minutes, and it ruined its first filter within a few days. Its design caused sharp large chips to slam and stab hard into that small filter filling it with large holes. A filter full of large holes no longer filters. Meanwhile with Christmas gifts to get out, I had a lot of rough lumber to prepare and needed something that would work. I had already gotten rid of my prior cyclone, so I went looking for help. I called the vendor and got pretty tough wearing my university engineering instructor hat to get to their senior engineer. He asked me not to tell anyone, but he admitted that the internal filter was something their president chose to implement without testing. It was a huge mistake and responsible for about half of their emails. He told me that they had worked out a special replacement fine bag filter and gave me the name of where to order it. I did and within just a few boards my chips that went right through the cyclone had blown a hole in the filter side. This cyclone separated so poorly that without a good fine filter it filled my shop with dust. After many calls that engineer admitted some pretty bad things about this firm and its president. Regardless, they could do nothing to make repair so I demanded a full refund for my friend. The engineer said he could not authorize that refund. I eventually spoke with the firm president who was an arrogant ignorant liar. He talked his way onto a couple of national organizations pretending to be an expert, but in reality he knew almost nothing about traditional dust collection, fine dust collection, airflow, blowers, ducting design, or cyclone separation. He admitted that his firm falsified their cyclone separation ability, falsified their maximum airflow advertising, and falsified their filters filtering ability. He also admitted flagrantly stealing the neutral vane from Jim Halbert then using his firm's financial might to force Jim to not say anything. He admitted stealing their ducting design program and changing it for their own use. He refused to honor his firm's money back guarantee. In short, this is not the kind of person I wanted anywhere near my world.

      • Decision Time: Constantly having to clean the filter, fix blown apart ducts, and clear the cone and duct plugging left me and shop covered in the dust this system was advertized to collect, plus left me spending almost as much time on my cyclone as I spent doing woodworking. This cyclone worked so poorly and the vendor had no integrity, so I decided to junk it right after finishing my Christmas projects and replace it with a used commercial Donaldson-Torit cyclone similar to what I installed at the university and my family shops.

      • Failure: Additionally, this cyclone worked so poorly I decided to junk it right after finishing my Christmas projects. I stupidly kept using it without venting outside because it did leave a clean looking shop and I thought its fine filter protected me. Instead before I could get rid of this piece of junk it landed me in the hospital, left me unable to do woodworking, and nearly killed me. My doctor sent me home on full time supplemental oxygen and told me to rest and figure out what went wrong and how to make repair.

  3. My Later Cyclone History

    I am very stubborn and did not want to give up either my three generations of tools or my favorite hobby in spite of my doctors saying no more woodworking until I did not have such strong allergic reactions.

    WoodSucker II Cyclone Disgusted, I started looking for some real help and got lucky. I discovered Larry Adcock built a significantly better cyclone. Larry's updated WoodSucker II cyclone was in a whole different class. Larry went with a properly proportioned woodworking cyclone with the right sized cone and dust chute so his cyclones did not plug every time we used a planner. Instead of the traditional only 40% efficient material moving impellers Larry designed a really tough caged impeller that had over 70% efficiency so it would with a 2 hp motor move as much air as the equivalent of a 4 hp motor. His cyclone moved more air than any other available small shop cyclone, so had the best collection. He incorporated a helical baffle better known as an air ramp which did an even better job than Jim Halbert's "neutral vane" so it put a lot less filter plugging dust into its filter. Larry also worked out a clever arrangement where the filter dropped its dust into the collection bag similar to today's cartridge filtered dust collectors. This let his customers clean their filters by simply turning off their cyclone and blowing down the outside of his filter. Larry also made his whole cyclone system from heavy gauge steel that he welded beautifully and coated in hammer tone silver paint. There was nothing in the small shop market that was even close in terms of performance or quality. Larry was kind enough to share with me his thinking behind his innovations. Unfortunately, his cyclone solution was a great "chip collector" but did not move the air needed to be a really good fine dust collector, or handle the airflow required for large shops like mine, so I found myself working on how to incorporate his solutions into my Wood Magazine cyclone.

    Dizzy's Cyclone My friend Dizzy lives nearby, is a spectacular craftsman who works metal and wood, plus a very inventive engineer who had already come up with many of his own solutions for making the Wood Magazine cyclone workable. He built one of the Wood Magazine cyclones, but ignored the too thin metal and made a true work of art. He figured out that the bags were not going to work, so he came up with a unique design where he stacked two commercial filters on a cleanout box and had the blower blow right into these filters. That design was very clean. He put a 4" connection flex hose connection on that cleanout that made filter cleaning easy. He simply attached a long hose to that 4" cleanout port and ran it outside, then turned on the cyclone and used an air hose to blow down the filter outsides. The fine dust on the filters blew away and vanished outside without the nightmare mess that filled my shop every time I had to clean the cyclone internal filter.

    Dizzy also solved the bad blower problem. He did a little research and discovered that the way professional blower firms compensate for the overhead of a cyclone is to use oversized blower impellers. It takes a lot of work to force air to turn in a tight separation spiral inside a cyclone. That work ends up adding right off the top about 3.5" to 5" of resistance depending on whether or not you have installed the "neutral vane" that Jim Halbert designed. That much extra resistance takes a standard 2 hp blower that with no resistance moves a maximum airflow of over 1200 CFM to only about 875 CFM if you use at least a 6" diameter duct. With the 4" duct we used to connect to the 4" diameter ports on most of our tools we were only getting 350 CFM. Dizzy used his TIG welder and added little tabs onto the ends of his blower impeller making it a larger diameter. The result is even with the cyclone resistance overhead, his modified blower moved the same air as it did when working without the cyclone overhead. This came with a small risk, because if the ducting got knocked loose, the blower with its oversized impeller tried to move too much air and could burn up a motor.

    Bill's Cyclone Unlike most, my engineering background allowed me to do some serious testing then come up with my own far better fine dust separating cyclone design. I had to start over with a whole new design that optimized the airflow and minimized internal resistance using things I learned working with rocket motor designs. I came up with a better solution designing a cyclone that moves more air with less power and provides more than six times better fine dust separation which is what we need to protect our fine filters that respiratory physicians recommend.

    My doctor came over and saw what I had done. He was so impressed he pretty much twisted my arm and helped me write an article sharing my solutions which launched these pages in early 2000.

    My design worked so well and these pages became so popular that many different vendors came to me and asked my help repairing their products. Building my website and helping these vendors was out of altruism as I did not want others to suffer or get blindsided as I was. My goal was not financial gain or vindictiveness against that top magazine rated vendor whose advertizing lies so harmed my health. I helped this firm by redesigning their blowers, cyclone cone, dust chute, cyclone inlet, cyclone outlet, neutral vane, filter stack, filter cleanout, and revised their ducting design program. I did the for the low cost import vendor that I despise because they flagrantly copy patented tools and play games with shell corporations, communist China, and international business games to avoid patent infringement. Although many like these low cost tools, most are unaware that if they get hurt by one of these tools that there is nobody to go after because all is a smoke and mirror game involving shell companies. Unlike these first two firms who not only failed to honor their payment agreements, and ended up threatening me legal suits I could not afford to defend, I also found there are many very reputable small shop firms. I helped PSI to redesign their their line of blowers and cyclones, plus the cyclone plans they sell with Wood Magazine. I similarly helped Jet Tools and Powermatic with evaluating and improving their new cyclone designs. Today every major small shop vendor except JDS now uses variations of my cyclone design shared on my Cyclone Modifications pages.

    Since I did that work in early 2000, our small shop market continues to be dominated by the same two high budget advertisers whose focus is to sell equipment not provide health protection. I oversaw the testing of every major brand and size of small shop cyclone during 2007 and 2008 and since 2000 have overseen four different magazine tests on dust collectors and cyclones. Rather than admit in these tests that the true measure of a cyclone separator is how well it separates, these vendor dominated magazine tests ignored cyclone separation and working airflow to instead focus on maximum airflows. Maximum airflow is typically twice real working airflow. How much maximum airflow gets measured depends of how big and good our blowers, what clever tricks are used and whether or not the test continues past the motor's maximum rated amperage. These tests did not even look at working airflow but instead tested with vendor recommended oversized test ducts to generate maximum airflows without attaching ducts, tool hoods, filters, and in many cases even cyclones. None except my cyclone provides much better separation than the inexpensive trashcan separator lids and one cyclone remains so bad it is only about 85% as good as a trashcan separator lid. Most dust collector and cyclone vendors advertize and sell fine filters that freely pass the fine invisible unhealthiest dust. Finally, our small shop forums are filled with vendor paid shills and forum administrators who get paid to recommend the same poorly performing cyclones. I was kicked off a popular forum that I helped get going because one of the vendors paid that forum owner to advertise their products. Likewise, these same forums are filled with first time cyclone buyers that are still convinced that because they spent so much, they got a great product. Clearly, you should not believe most available cyclone testing and recommendations.

Copyright 2000-2015, by William F. Pentz. All rights reserved.