Cyclone & DC Testing
- Best Practices
- Dust Collection Evaluation
- Frequently Asked Questions
This web page provides summary information from our testing most brands and sizes of small shop vacuums, dust collectors, cyclones and air cleaners plus detailed results from the more credible magazine testing.
I started these web pages after using the best magazine rated cyclone landed me in the hospital due to fine invisible dust exposure. When my health failed to get better at my doctor's advice I paid to have professional air quality testing done on both my shop and home. Both tested with dangerously high airborne wood dust levels thousands of times over the EPA limits and my so called best magazine rated cyclone tested to move between one third and one tenth one tenth the vendor advertised airflow. I did considerable research and found the small shop vendor community has known since before 1994 that almost all of their shop vacuums, dust collectors, cyclones and even air cleaners are mostly dust pumps that move too little air to amply collect the fine dust and most come with such open filters that they simply blow the invisible unhealthiest dust right through. As a result, when we vent almost all dust collection equipment inside we create a bad false sense of security where we get clean looking shops that particle meters show carry dangerously unhealthy invisible dust levels. Since most of these vendors advertise or imply good health protection and have done so for decades, all are subject to major litigation for selling equipment that does not provide the advertised health protection. After these pages exposed the worst of these vendors including my cyclone maker, these vendors want me and these web pages gone. Informed people pose a very serious threat to their firms' survival because people will not buy equipment that they know makes matters worse and those injured by this equipment could ban together and put these frauds out of business. My sharing these pages started a long still ongoing war that frankly they are winning. They actively pay shills to work all the major woodworking forums to put me and these pages down at every opportunity. They have falsified information concerning me on their web pages. They have even gone so far as to use their advertising dollars to significantly influence the various woodworking magazines and major woodworking forums. A forum I helped start no longer even lets me post because they bought the forum owner with a new dust collection system and considerable pay to feature him and his shop in their advertising campaigns. At this point what we have is a dwindling grass roots effort to try and make others aware of the dangers of fine dust exposure and what we need for good fine dust collection.
Probably their most successful suppressive tactic to date concerns these web pages. After seeing the dismal test results from having my own so called magazine best cyclone system tested, I went looking for credible small shop dust collection tests and asked if others had similar bad experiences. The magazine tests failed to follow industry standards and often used apple and orange test procedures that make some vendor equipment look bad and other equipment look much better than in actual use. Most magazine tests and all vendors advertise maximum air volumes which after we add the overheads of our tool hoods, tool ports, ducting, filters and separator end up being over double the airflow we get in real use. I found a single engineer who had published what appeared to be some very credible tests on one of the early woodworking forums. He was no longer posting and after I did some digging I learned he was thrown off both of the two forums he previously frequented. Moreover, there was a rumor that because of his calling the president of the same firm who made my cyclone a flagrant liar, he ended up being sued and settled by agreeing to no longer post on those forums. I contacted him and his only comment was he was enjoined from saying anything. Another scientist friend contacted me and shared that this same cyclone firm stole one of his inventions and incorporated it into their cyclones without his permission, gave him no credit, and then also sued him when he complained on line. A third engineer showed that same firm stole their "free" ducting design program from a shareware firm without paying that firm. Worse, that ducting design program was for larger shops who did not use blast gates as all stations work at once, so this "best" cyclone firm actually sells graduated ducting designs that just don't work in small shops that only use one tool at a time. Many responded with what they experienced and these pages shared what they said. That information proved too emotional without any supportive facts. What was most interesting is most of the strongest supporters of particular dust collection solutions became even stronger speaking out against those same units within a year or two.
Wanting some accurate test results I talked the many scientist and engineer friends who contributed to these pages to do this testing ourselves. We started by finding out what the industry requirements really were and how to do professional testing. We agreed upon a set of standards and test procedures. We used the same professional freshly calibrated and certified digital test meters used in certified engineering tests. We followed the airflow test standards recommended and used by the experts who write the industry standards. Knowing that some vendors have a history of submitting equipment for testing that has relabeled bigger blowers and motors than they actually sell, we only tested units purchased at local outlets. We tested our own equipment and equipment volunteered by many others. We also made sure that we had different testers independently test at least two different units of each brand, size and type unit that we evaluated. When the test results showed a discrepancy we had others independently test different identical units to resolve any issues and ensure the accuracy of our results. Knowing we also wanted to test filter performance, we researched the the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) standards and followed their recommendations for filter testing. We purchased brand new filters for each unit we evaluated and tested these filters with calibrated test dust to evaluate filter efficiency. In addition to the standards that keep our floors, tools and work surfaces clear, we now have air quality standards, so we also did a standard air quality tests in each shop we tested. Doing these air quality tests required a significant investment as the least expensive of these test meters cost over $8000 each. There were none of the games played like most magazine apple versus orange comparisons where they tested the systems with different or over sized test pipes, special bell shaped test ends that falsely magnify airflows, the nonsense of running blower motors at far over their rated amperage, or use of meters that don't even have the ability to measure the airflow or particle size ranges being tested.
My professor and engineer friends tested most brands and sizes of small shop vacuums, dust collectors, cyclone separators and air cleaners and I shared the results of those tests here on this page but within a week all had to be taken down. Two of the biggest small shop cyclone vendors and one dust collector vendor tied me up with litigation demanding that I remove these test results and also remove every instance of those vendor names from all of my web pages. I spent thousands on attorneys who all assured me we would win eventually, but at too high of a cost. All said that the courts almost never award damages or attorney fees in these kinds of business suits, so this all had to be out of my pocket. Worse, if I did not remove these test results and vendor names immediately, these vendors would be granted a court order to force me to pull down not just the results shared on this page, but all of my web pages for the years they could drag out these nuisance suits. Regardless, each of these suits would cost me at least $25,000 to defend and I do not have a spare $75,000 or more to throw away. Three different woodworking magazine editors shared they had the same problem where the big name vendors forced them to omit negative test results and to change their testing to make certain equipment appear to perform far better than it does in real use. I apologize in advance for not being able to share all our detailed test results.
Since I started testing in early 2001, little has changed because the vendors continue to do little to nothing in terms of improving their shop vacuums, air cleaners, dust collectors or cyclones except in some cases they use better filters. Frankly, our ongoing testing shows the vendors just keep copying each other and selling the same "chip collection" designs that we already know pass dangerously high amounts of airborne fine dust.
Rather than just start testing, we took the time to understand what this industry recommends. My other web pages give the specific detailed requirements and why, so the following summarizes the requirements to get good dust collection.
The first thing we discovered is woodworkers can mean two different things when they say dust collection. Most areas require that commercial shops subject to fire marshal and building inspection provide dust collection systems that keep our tools, work surfaces and floors clear of the dust and chips produced during woodworking. Many call this traditional dust collection "Chip Collection" as it collects the same sawdust and chips we would otherwise sweep up with a broom. Today most larger commercial facilities not only provide good chip collection, to protect worker respiratory health they voluntarily use dust collection systems that ensure airborne dust levels do not exceed one of three standards. Since also providing good fine dust collection is a requirement in many areas, dust collection has evolved for them to also mean good chip collection plus good airborne dust collection. To be consistent and minimize confusion, our test group and these web page refer to traditional dust collection as "chip collection" and when we also collect the airborne dust we call call that "fine dust collection".
There are at least three major woodworking air quality standards, the OSHA standard, the ACGIH standard, and the EPA standard. OSHA considers all airborne wood dust as only a nuisance meaning irritating except for Western red cedar which is considered toxic. The OSHA standard for airborne nuisance dust applies to all airborne dust which by definition consists of particles sized under 30-microns or just a bit smaller than half the diameter of a typical human hair. The OSHA standard allows up to 5 milligrams of airborne dust per cubic meter of air. With an industry already in serious financial trouble due to much lower cost imports, the courts took sympathy on woodworking firms and threw out the 1989 OSHA standard before it was fully implemented. Meanwhile the medical records, insurance data, and peer reviewed medical research clearly shows all inhaled fine dust seriously damages our health. The American Conference of Industrial Hygienists (ACGIH) sets work place standards and their airborne dust standard only allows 1 milligram per cubic meter of air which is five times tougher than OSHA proposed. While OSHA, ACGIH, the courts and political leaders were trying to decide on an appropriate standard for fine airborne dust, the EPA and the European Union both followed the recommendations of medical experts and established near identical standards. The medical researchers found that fine inhalable dust particles sized under 10-microns, known as inhalable dust, are invisible without magnification and these particles slip right by our bodies' natural protections, lodge in our respiratory systems then irritate, damage and scar our tissues. The peer reviewed medical research clearly shows every fine dust exposure causes a measurable loss in respiratory capacity and some of this loss becomes permanent. The EPA airborne dust standard only allows 0.1 milligrams of fine dust per cubic meter of air which is fifty times tougher than the proposed OSHA standard. The EPA enforces this standard across the U.S. for residences and office buildings, but does not have oversight responsibility over industrial facilities such as large woodworking concerns. Regardless, to protect worker health almost all larger woodworking facilities voluntarily comply with the ACGIH standard and most try to maintain the EPA standard.
There are many who strongly recommend even tougher standards and additional protection for airborne wood dust because it is far more dangerous than most other airborne dusts. An electron microscope shows half of the problem. Unlike most other airborne dusts, wood dust particles are covered with razor sharp edges and sharp often barbed points that cause lots of irritation and tissue damage. The other half of the problem is worse. Wood dusts contain and carry toxic chemicals that cause additional health problems including irritation, sensitivity, allergic reactions, poisoning, nerve damage, and even increase risk of certain nasal and respiratory cancers.
For most standards are not very real unless we have some perspective. The EPA standard does not allow much airborne dust, only 0.1 milligrams per cubic meter of air. Most small woodworking shops are sized about the same as a typical two-car garage which contains less than 100 cubic meters of air, so launching just 10 milligrams of fine dust airborne will cause an average shop to fail an EPA air quality test. This 10 milligrams is not much dust, barely two tiny thimblefuls. We launch this much dust airborne when we slap a dusty apron or hand saw just over 7" of 3/4" thick hardwood. Woodworking makes lots of dust compared to how little it takes to create unhealthy air or fail an EPA air quality test. OSHA testing shows every twenty pounds of sawdust that we make also makes about 5 1/3 ounces of fine dust by weight. There are 28349.5231 milligrams in each ounce so every twenty pounds of sawdust makes over 151,410 milligrams of fine dust. Divide by the 10 milligrams it takes to contaminate an average two-car garage sized shop and we see that every twenty pounds of sawdust that we make also creates enough fine dust to cause 15,141 typical two-car garage sized shops to fail an EPA air quality test. Although many small shop vendors advertise 99% collection efficiency, each 1% they miss collecting out of every twenty pounds of sawdust produced launches into our shop air enough fine dust to cause 151 typical small shops to fail their air quality test. The worst news is this fine wood dust does not break down unless it gets wet, so unless we vent outside or have really good collection, most shops rapidly build such high levels of fine dust that just walking around stirs enough dust back airborne to fail an EPA air quality test without doing any woodworking. This is why venting outside is safest.
- Best Practices
For our testing we also researched in considerable depth what the dust collection industry leaders do to provide good dust collection. Most of the major manufacturers who guarantee the performance of their dust collection equipment provide detailed on-line engineering specifications and requirements so the air engineers who install their equipment will be successful. Much of this information required some translation to make understandable, but we did that translation then made sure our testing followed best industry practices.
- Hood Requirements
Our blades, bits, cutters and sanders throw off dust and debris at over 100 miles an hour. Our dust collection airflows move air at under 45 miles an hour. Our half as fast dust collection airflows have zero chance of good dust collection unless we start with good hoods that control, direct and deliver these fast moving dust filled air streams for collection. Without good hoods, we are wasting our time and will never get good dust collection.
- Air Volume Requirements
We need ample airflow to get either good chip collection or good fine dust collection. Over eighty years of industry experience shows that most small shop stationary tools require 350 cubic feet per minute (CFM) air volume to get good chip collection. Although a good shop vacuum provides excellent fine dust collection if all the dust being made is contained, most use older tool designs that provide very poor dust containment. The expert firms that guarantee customer air quality found that with older tool designs the only way to pull in the fine dust is to surround the working areas of our tools with a big low pressure area that sucks in the fine dust fast enough that normal room air currents cannot blow it all over. Decades of experience by the large dust collection equipment makers shows to get good fine dust collection we must move much more air to get good airborne dust collection. The experts who guarantee air quality levels shared that on small shop tools that get good chip collection with 350 CFM we need at least 800 CFM to meet minimum OSHA air quality, need to move 900 CFM to meet the five times tougher ACGIH air quality standards, and must move a full 1000 CFM if they are going to meet the EPA, European Union and medical recommended standards. It takes moving this much air to build a low pressure bubble roughly fifteen and a half inches all around the working areas with air moving at least 50 feet per minute to pull in the fine dust before it gets spread all over by normal room air currents.
- Air Speed Requirements
The experts also found it takes a minimum of 3800 feet per minute (FPM) airspeed to actually pick sawdust and light chips up. Anything less and the chips will not become airborne. We also need this same 3800 FPM airspeed to keep vertical ducting runs from plugging. They found we need at least 2800 FPM airspeed to keep horizontal ducting runs from building piles. Ducting piles pose a serious fire danger as any spark can quickly get blown into a serious ducting fire. When ducting piles break loose these piles also slam down our duct so hard they can ruin our ducting joints, cyclones, blowers and especially our filters. Finally, we need to get rid of the fine dust by either blowing it away outside or filtering. Most who blow their fine dust outside use traditional cyclone separators that pull off the heavy dust then blow the remaining airborne dust away outside where it quickly dissipates with no visible trace.
- Tool Port and Ducting Requirements
At the low pressures that dust collection blowers work, air is more like water and will barely compress at all. This means that any small port, small duct, roughness, or tight bends in our ducting acts just like a partially closed water valve and will severely limit airflow. This is why the experts always use as smooth of duct and flex hose as they can find. Also, just like water the size of our duct limits how much volume will flow at typical dust collection pressures. Using a 1" diameter pipe in our duct limits a flow that is 1000 CFM in a 7" diameter duct to only 22 CFM. A 2" diameter duct limits our flow to only 87 CFM, and a 3" diameter duct to only 196 CFM. This is why the experts never use less than a 4" diameter duct connected to a standard dust collection and only recommend connecting 3" and smaller diameter duct to shop vacuums which move air with about ten times more pressure. Our 4" diameter duct only moves 340 CFM, yet we need at least 350 CFM to get good chip collection at most tools. A 5" diameter duct only moves about 545 CFM and 6" duct only 785 CFM. This poses a serious problem as most small shop vendors recommend and configure their dust collection systems with no larger than 6" down drops. These 6" down drops with their 785 CFM airflow fall short of the the 1000 CFM that decades of experience by the top firm that guarantee customer air quality say we must have to get ample good fine dust collection to avoid failing air quality tests. To support a real 1000 CFM airflow we need 7" diameter ducting or an over sized blower that generates extra pressure.
- Filter Requirements
Filter Recommendations - The medical experts recommend we always vent our dust collection systems outside, but if we have to filter our air, we need to use filters fine enough to protect our health. The American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE) sets the international standards for rating filters used to protect our health and filter indoor air. Since 1987 filter makers rate their filters with an ASHRAE minimum efficiency reporting value, commonly known as its MERV rating. Health experts and the EPA both recommend use of filters with at least a MERV-15 rating. MERV-15 filters filter off all airborne bacteria and are often used in in-patient hospital rooms. A MERV-15 rating means a clean new filter prevents 95% of all particles sized 0.3 to 0.5-microns in diameter and larger from passing through.
Filter Seasoning - As a filter gets used it seasons which means it traps particles in the filter pores that do not come out with normal machine shaking and air blast cleaning. Over time a filter will build up as much of these trapped particles as the filter can hold and is then known as a fully seasoned filter. These trapped particles known as the dust cake block other particles from getting through our filters. A fully seasoned filter increases airflow resistance but also can provide ten to twenty times better fine dust filtering than a new filter. Most filter makers give both the resistance level and filtering level for fully seasoned filters. Air engineers need to know the resistance for a fully seasoned filter to make sure they use filters with enough surface area so as the filters seasons they do not build up so much resistance they kill the airflow we need for good dust collection. Commercial dust collection systems check and record the pressure after every filter cleaning as this pressure lets us know when we need to clean and when we need to replace our filters. This recorded pressure after each cleaning rises while a filter seasons, then levels off when the filter becomes fully seasoned. Then as the fine particles wear out our filters the pressure after cleaning slowly falls because air can more easily pass through the filters. Most commercial dust collection systems require replacing our filters when the pressure falls two water column inches of pressure below the filter's fully seasoned level because that is when the filter is too worn to provide good filtering. Also, when the air pressure climbs about two water column inches higher than the pressure after the last filter cleaning, these systems automatically clean the filters again.
Filter Rating Confusion - Although ASHRAE sets the only formal filter rating standard for filters used to protect our health, most dust collection vendors only work with fully seasoned filter ratings. By law most dust collectors and cyclones must be either certified as fire and explosion proof or instead installed outside behind explosion and fire proof barriers. The cost to build and get certification for fire and explosion proof commercial dust collectors and cyclones is very high, so most commercial dust collection systems end up being placed and vented outside. Filters vented outside do not have to protect our health, so air engineers use the filtering and resistance levels for fully seasoned filters.
Filter Risks - The ugly part of this is small shop vendors are only regulated based on what we as consumers buy, so most small shop vendors advertise the filtering levels for fully seasoned filters intended for outdoor use on equipment that we must use and vent inside. Using filters rated for outdoor use can blindside us with dangerously high amounts of fine dust three different ways. First, in small shops most dust collection filters take a year or more to fully season. During the year or more long seasoning time we breathe the unhealthiest fine dust particles that a properly ASHRAE rated filter based on its clean new performance removes. Second, as a filter gets used the airflow pins larger particles to the filter surface. These trapped particles catch and keep smaller particles from going through our filters which improves filtering while the system is running. Most filters are coated with a release agent that causes these particles to fall off our filters when the air gets turned off. The particles drop inside our systems so when we turn these systems back on the small unhealthiest particles go airborne first and shoot right through our filters if the filters are not fine enough. Third, even fully seasoned filters still slowly pass the finer particles that go through clean new filters at about the same rate that new particles build in the filter pores. Filters advertised with seasoned instead of ASHRE ratings makes them dust reservoirs that turn our dust collection equipment into dust pumps that often contaminate our shops beyond EPA standards by just turning on our systems. This is why ASHRAE requires that indoor filters be tested and rated when clean and new.
HEPA Filters - There are many small shop vendors who also falsely claim they sell HEPA level filters, but instead sell far more open filters that offer little to no protection. Most couch their advertising to say "HEPA" equivalent or use other words to qualify that they are not really selling HEPA filters. HEPA is the standard set in the 1950s for filters to protect against radioactive fallout particles. HEPA filters filter off bacteria, most viruses and very fine particles so are used to ensure hospital operating room air quality. For a filter to be a true HEPA filter it must have a MERV-20 rating which means when clean and new it separates off 99.97% of all particles sized 0.3-microns and larger. Additionally, to be a true HEPA filter each separate filter must be individually tested and certified with its own unique registration number.
Filter Sizing - Filter sizing is important. If a filter is not large enough to handle the airflow it receives then the filter will add so much resistance it will kill the airflow needed for good collection, plus it will need constant cleaning. Likewise, if a filter is not large enough to handle the amount of material it needs to filter, then the filter will quickly load up and get so impacted it also will stop the airflow needed for good dust collection. The finer our filters the more often we must clean them. Cleaning filters is bad news because cleaning forces the fine dust particles with their razor sharp edges and sharp often barbed points to cut and tear their way through the filter material. The more we clean our filters the faster they wear out. Woodworking makes so much dust and the filters need cleaned so often that most commercial shops with properly sized filters must replace fine filters every three months. Filters fine enough to protect our health are expensive. Most filter makers recommend that filter fine enough to protect our health have a minimum of at least one square foot of filter area for every 4 CFM of airflow. To minimize cleaning and maximize filter life most filter makers recommend doubling that minimum area to at least one square foot of filter surface area for every 2 CFM of airflow.
Filter Surprises - Many small shop users even with very fine filters get a huge surprise if they monitor particle counts. After they make lots of airborne dust that does not get collected as it is made, invariably the next day as soon as they turn on their dust collection systems the particle counts go crazy often beyond EPA maximums without doing any woodworking. The reason is our filters are made with polyester plastic fibers that develop considerable static charge as our dust collection systems run. If we have dusty shop air when we turn our dust collection systems off, that high static charge collect lots of the fine airborne dust from our shop air overnight. This dust collects on the outside of our filters, so when we turn our dust collection back on that immediately launches this collected dust airborne.
- Blower Sizing
Blower technology is very mature. Almost every U.S. brand name blower with the same motor speed and same type and sized impeller will deliver near identical performance. Performance is so consistent that those who specify blowers use any vendor fan table to properly size a blower and its motor regardless of brand. Any diligent student can use the standard blower tables to easily and properly size a blower. As we add tool hoods, ports, ducting, flex hose, a separator, and our filters the resistance in our system known as its static pressure climbs. Static calculators such as shared on these pages will help us compute the maximum static pressure for highest resistance ducting run and also compute the lowest static pressure. We use the maximum and minimum static pressures with a good blower table to size our blower. The maximum static pressure is used to tell how big of an impeller we need to ensure moving enough air at a given resistance. Once we know the impeller size we use that same table with our lowest static pressure to show how much horsepower that size impeller will use when working against the least resistance. A blower moves the most air when it has the least resistance. The more air a blower moves the harder a blower motor must work and more horsepower We then size our motor by going to the closest standard motor size that will produce at least that maximum horsepower. If we study the standard commercial blower tables we see it takes at least a 3 hp motor turning not less than 14" diameter impeller to power a dust collector amply to move our needed 1000 CFM required for most small shop stationary tools for good fine dust collection. Forcing the air inside a cyclone to turn in a tight separation spiral adds more resistance meaning static pressure so we often need a bigger impeller and about one half horsepower larger blower to power a system with a cyclone separator. These same blower tables show most small shops need at least a 4.2 hp motor turning at least a 14.5" diameter impeller to power a cyclone. Since most motors come in 3 or 5 hp size, we really need a full 5 hp motor for cyclone based small shop dust collection systems to get good fine dust collection. We need to step up to a 16" diameter impeller on our 5 hp motor to overcome the extra ducting to support good fine dust collection in larger than average two-car garage sized shops.
- Hood Requirements
Dust Collection Evaluation
False Sense of Security - Sadly, most small shop vendor dust collection products are a mess. Small shop vendors made smaller copies of traditional commercial dust collection equipment and copies of each other's tools with arbitrary changes. The worst assumed they could add finer filters to these units and instantly get good fine dust collection. There are no standards or controls on small shop vendor products except what we as customers exercise through our purchasing decisions. Word of mouth and magazine reviews are just about all we have to go on to make informed dust collection decisions and most of this information is bad. Unlike most woodworking operations that are pretty obvious, the unhealthiest dust is invisible without what were prohibitively expensive particle counters. Likewise, airflows are also invisible so unless we buy test equipment and learn how to do our own testing, there is really no way to accurately ensure good airflow or know if vendor advertising is accurate. Most small shop vendors, woodworking authorities and even magazine editors fail to take the time to learn the risks of poor dust collection or to understand the technology and science behind good dust collection. This lack of knowledge on the part of woodworkers and our experts combined with a lack of standards, no oversight, and shoddy engineering by our copycat vendors to create a nightmare mess in terms of small shop dust collection.
This dismal state of affairs inspired us to take nearly two years to complete the initial testing of almost every brand, size and type of small shop vacuum, dust collector, cyclone system and air cleaner. The results badly embarrassed our small shop vendors and woodworker community. We evaluated each dust collection solution based on its airflow and filtering, plus checked each shop with the same air quality tests. Our testing consistently found almost all small shop vacuums, dust collectors, cyclone systems and even air cleaners create a bad false sense of security. Poor collection and filtering caused even the cleanest looking shops to build up such high levels of fine invisible dust that just walking around stirred enough dust airborne that most failed their EPA and ACGIH air quality tests without doing any woodworking. Most vendors provide such open filters the filters become such bad dust reservoirs that just turning on the dust collection systems often launched enough fine invisible dust that most shops failed their air quality tests. In addition to failing the air quality tests before starting any woodworking, we found that before completing our sawing test most dust collectors and cyclones let the airborne dust levels climb to as high as normal room air currents can support. Our tests showed most small shop vendor dust collection solutions perform so poorly that most before starting woodworking should put on a good NIOSH approved dual cartridge respirator mask and turn on a strong fan blowing out the back of their shop with a front door open enough to create enough ventilation to avoid building up the fine dust. Our particle counters showed the mask and fan must stay on for about a half hour after we stop making dust.
Small Shop Dust Collection Product Overviews
Small shop vendors have long made their livelihoods by copying and downsizing larger commercial tools, having these tools built overseas by minimal cost labor, and then selling to small shop woodworkers. Most small shop vendors make bad compromises with their designs, performance and documentation which combine to create safety issues and dangerously high particle counts that put us as woodworkers at risk.
Safety Instructions - Not one single small shop dust collector or cyclone came with a recommendation that these units are not fire and explosion certified, so will fail fire marshal and building inspections as well as most home insurance policy inspections if installed inside our shops. To pass these inspections these units must be placed outside in their own covered area behind a fire and explosion proof barrier. This requirement is actually excellent advice and venting outside is also the best way to use these units to avoid serious fine dust problems.
Respiratory Protection - None even mentioned you should always wear a good NIOSH dual cartridge respiratory mask and wear protective clothing whenever making fine dust and when cleaning or changing filters.
Tool Port and Hood Upgrades - Not one small shop dust collector or cyclone vendor discussed the reality that these systems will not provide good fine dust collection unless we start by upgrading most traditional tool ports to support ample airflow and upgrade tool hoods to control, direct and capture the fine dust. Our air quality testing verified the information published by the major vendors who guarantee customer air quality. The experts found most traditional tools come with hoods that need upgraded to control and capture the fine dust. They found most traditional tools either come with no dust collection ports or hoods and that those with dust collection often had tool ports, hoods and internal air channels too small to support good fine dust collection. Most small shop stationary tools come with 4" diameter ports and really need multiple ports with a combined cross sectional area equivalent to a 7" diameter port to flow enough air for good fine dust collection. My Ducting pages share how to upgrade your tool ports and hoods.
Ventilation Warning - No shop vacuum, dust collector, cyclone system or air cleaner came with any warning that their systems lack the airflow for good fine dust collection and most come with filters that pass significant amounts of fine dust so when vented inside they cause our shops to rapidly build dangerously high invisible dust levels. Most small shops had so much fine invisible residual dust built up in their shops that our shop air quality tests showed even in very clean looking shops that just walking around without doing any woodworking or even running the dust collection systems launched enough fine invisible airborne dust that these shops failed their air quality tests. Our tests showed most need to run a strong fan blowing out the back of your shop with a front door open enough to get good ventilation. Our particle counters showed the fan must go on before we start making dust then it needs to stay on for about a half hour after we stop making dust to avoid accumulating the fine invisible dust.
Misrepresented Filtering - Every major small shop dust collector, cyclone and air cleaner gravely misrepresented the protection offered by their filters. Almost all small shop vendors advertise and supply filters rated as fully seasoned filters instead of giving ASHRAE MERV ratings. This means their filters pull of the visible particles but freely pass the unhealthiest invisible particles sized under 10-microns. It takes a year or more in most shops for filters to fully season, and fully seasoned filters still pass particles smaller than the filter's new clean MERV rating after seasoning, just at a slower pace. This is why ASHRAE requires that indoor filters always be tested and rated when clean and new. This is also why the medical experts always recommend at least use of ASHRAE MERV-15 or finer filters. We found most fine filter upgrades and the newer finer filters being sold today still freely pass the unhealthiest under 5-micron sized particles. We were very surprised to find that most ceiling mounted air cleaners that we buy to protect our health were equally open and most freely passed the same under 5-micron unhealthiest fine dust particles. We found most of the fine filter upgrades for shop vacuums performed as advertised but only Fein and Festool shop vacuums came standard with filters that consistently performed as advertised.
Insufficient Filter Size - Our tests also showed almost every shop vacuum, air cleaner, dust collector and cyclone came with gravely undersized filters. Filters with insufficient surface area kill the airflow we need for good collection, need cleaned too often and wear out too quickly. The thicker all polyester filters only need about half as much filter area and can be washed up to three times to partially restore filter performance, but they cost twice as much initially. Commercial dust collection systems rarely use the all polyester fine filters because firms find that the down time and overhead to clean the all poly filters is more expensive than simply replacing the blended polyester cellulose filter cartridges. Industry standards recommend our blended fine filters that most use for dust collection have at least one square foot of filter surface area for every 2 to 4 CFM of airflow. That means systems that offer the 1000 CFM airflow we need for good fine dust collection should have blended filters with at least 500 square feet of surface area. Most dust collectors and cyclones advertised to support 1000 CFM airflows came with under 125 square feet of filter area instead of the 500 square feet the filter makers recommend to minimize cleaning, maximize airflow and optimumize filter life.
Filter Discussion - We had lots of discussions as to why vendors use filters they know are too open and too small. Our consensus is that the more open filters not only cost the vendors significantly less, small shop vendors must use more open filters to avoid customer complaints and immediate upset with system performances. Virtually all existing dust collectors and cyclones except those sold by Clear Vue pass 100% of the fine dust and more right into the filters. This dust loading requires commercial shops to clean filters roughly every two hours of use or the airflow drops until we no longer get good collection. That is why most larger commercial shops have automatic filter cleaners that either shake or use a blast of air to clean the filters. This high dust loading also requires most commercial shops to replace their fine filters roughly every three months of full time use. That level of cleaning and the high expense for such frequent replacement is far beyond what most small shop users will tolerate. More open filters cost less plus the more open the filter the smaller it can be, less frequently it needs cleaned to maintain airflow and longer it will last. The bottom line is these too open filters created a bad false sense of security because they filter off the visible dust leaving clean looking shops that consistently tested with such dangerously high amounts of airborne dust that just walking around stirred enough airborne to fail EPA air quality tests.
Upgraded Filters - As a result of the results shared here and a strong push from customers, many small shop dust collector and cyclone vendors now provide real 0.3 to 0.5-micron filters meaning they have a MERV-15 or better rating that the medical experts recommend. Finer filters are significantly more expensive than the more open filters previously provided. Our continued testing of these newer filters shows most small shop vendors have continued their practice of suppling fine filters with far too little surface area. Most today have about one quarter of the surface area that filter makers recommend for the loading we get with wood dust going through a traditional cyclone design. Undersizing small shop filters creates an interesting problem which explains why so many who at first swear by their new dust collectors and cyclones then find within a year that they hate these systems. At first these systems with undersized filters work well, but over the year or more it can take a small shop fine filter to fully season these filters increase in resistance and need emptied progressively ever more often to maintain good airflow. Eventually the seasoning causes these undersized filters to develop so much resistance they kill the airflow needed to get good fine dust collection. We found many vendor fine filters became so restricted they even killed the airflow needed for good chip collection. Between the need to constantly empty their finer filters and airflows that no longer provide good collection, many get very frustrated at their dust collection solutions that initially worked well.
Bogus Collection Claims - Although many vendors claim the ability to concurrently collect from multiple tools working at once and provide units that come with splitters to make them appear able to collect from multiple tools running at once, most lack the airflow needed to provide good fine dust collection at more than more stationary tool running at a time. The tests showed huge discrepancies between advertised and measured airflows. We found no under 2 hp cyclone and no under 1.5 hp dust collector moved the real 350 CFM minimum required to get good chip collection on more than one stationary tool running at a time. We found no under 3 hp dust collector or under 5 hp cyclone had the full 1000 CFM airflow minimum needed to good fine dust collection at more than one stationary tool working at a time.
Undersized Ports and Ducts - Our test measurements showed no dust collector under 3 hp or cyclone under 5 hp except for the Clear Vue generated enough pressure to pull more than 349 CFM through 4" diameter duct, 545 CFM through a 5" diameter duct, and 785 CFM through a 6" diameter duct. Strangely, the cyclone and dust collection vendors who made ducting recommendations never recommended over 6" diameter duct for down drops, so all these other systems were limited to 785 CFM airflow. We have over four decades of experience shared by the major firms who build commercial dust collection systems shows to get good fine dust collection at small shop stationary tools we need at least 1000 CFM which requires at least 7" diameter duct. Almost all small dust collection systems lack the pressure to move 1000 CFM with anything less than 7" diameter main and down drop ducts. To get the 1000 CFM needed for good fine dust collection through smaller sized duct, we must use special blowers with over sized impellers that generate higher than normal pressures. I found 7" diameter duct, splitters, and connections so difficult to find, expensive, and bulky to work with that I designed my blowers with over sized impellers that generate far higher pressures permitting use of 6" diameter mains and down drops to move the required 1000 CFM.
Dangerous Duct Planning - The only two vendors that offered duct planning gave dangerous advice. They shared the duct planning used for large facilities that use huge blowers ample to collect from all machines working at the same time with no blast gates. The resulting complex graduated ducting plans look very impressive, but just don't work when used in small shops that only collect from a single machine working at a time. The smaller down drops in these designs so limited the airflow that the mains lacked sufficient flow to stay clear. When collecting from tools with smaller down drops the air in the mains measured as moving far too slow to keep vertical runs from plugging and horizontal runs from building up dust piles. Dust piles in our ducts pose a very serious fire hazard as any spark can get blown into a serious fire, plus when these piles break loose they slam down our duct hard enough to break apart our ducting joints, go right through cyclones to ruin blowers, and ruin filters.
Filter Instructions - Most came with fine filters, but gave no clue as to when we need to clean or replace filters or any of the normal filter preparation that should be done.
Exaggerated Airflows - All the major small shop vendors advertise maximum instead of the working airflows. Relying on these maximums ends up with about half the airflow we need because maximum airflows are just about double real working airflows due to the resistance of our tool hoods, ducting, separators, and filters. Worse, all of the major vendors except for Delta, Jet, and Powermatic even exaggerated these maximum airflows.
Exaggerated Horsepower - Many import vendors gravely exaggerated motor horsepower. Many vacuum cleaner makers and even the most popular import dust collector vendor all claim at least 2 hp to as much as 6.5 hp from their motors which plug into a U.S. standard 120 volt 60 cycle power outlet. Normal home wiring will not support more than 1.6 horsepower without popping standard 20 amp circuit breakers.
Exaggerated Separation - Most vendors claim their cyclones provide 99% separation efficiency which they get by testing with previously collected dust. Previously collected dust no longer contains the roughly 15% of the dust by weight which is airborne dust that goes right through most traditional cyclone designs. Previously collected dust also does not contain the roughly 2% of the debris by weight that consist of strings, shavings, hairs, and other odd shaped pieces that have an air profile that acts like a sail or parachute to pull these pieces right through the cyclone. As a result, at best these traditional cyclone designs that all major small shop vendors except two use should actually report separation rates for their cyclones below 82%. The two vendors who offer short squat cyclones that use unique designs instead of the standard most others used had cyclone separation efficiencies below 75% by weight.
For our testing we evaluated separator efficiency, filter efficiency, and combined overall system separation efficiency. We weighed a standard piece of shelving material and weighed the collection bin and filters before doing any cutting. To ensure almost all dust was collected we used a wooden fence with a blade cutout that enclosed the table saw blade so no dust escaped during cutting. After cutting a fixed number of feet, we then weighed the remaining board, the collection bin and the filters. Depending on the unit tested getting weights required weighing many of the other dust collection components. The board weight difference showed the total dust produced. The bin weight difference divided by total produced dust gave separator efficiency. The filter weight difference showed how much dust landed in the filters. Total bin difference plus filter difference divided by total dust produced gave overall efficiency.
We found an inconsistent mess when it comes to small shop blowers used on shop vacuums, air cleaners, dust collectors and cyclone systems. Blower technology is very mature meaning almost every U.S. brand name blower with the same motor speed and same type and sized impeller will deliver near identical performance. Any diligent student can easily look up the engineering to turn out excellent blower designs. Performance is so consistent that those who specify blowers use any vendor fan table and will get near identical blower performance regardless of brand. We found the higher priced imports that have been in use for a while tend to work pretty well and deliver almost exactly the same performance as the leading U.S. made blowers. The newer and lower cost imports delivered much worse performance with the worst at less than half what we would expect from traditional blowers. Our testing found almost all lower cost imported blowers whether on dust collectors or cyclones, had many major design, copying, and manufacturing problems built right into each unit. The differences include poorly shaped and formed blower housings, constrictive roughly made inlets and outlets, poor quality motors that really don't deliver advertised power, poorly designed and made impellers with rough parts that ruin efficiency, and roughly made parts that significantly interfere with airflow. In short, unlike the near identical performance expected from reputable blower makers, out imported shop vacuum, air cleaner, dust collector, and cyclone blowers all delivered varying performance with the best only matching standard U.S. blower performance tables.
- Dust Collector Testing
Our dust collector testing tested to see if each dust collector moved ample air for good fine dust collection and if it provided ample filtering.
As expected from our blower evaluations, of all the major advertised dust collector vendors only the Delta and Jet families of companies provided dust collectors that actually moved the maximum airflows they advertised. Likewise, only Jet and Delta made dust collectors with 1.5 hp motors able to move a real 800 CFM when challenged by the minimal resistance involved when we have just enough flexhose to move a portable dust collector between machines. All other vendors had so many blower and dust collector design errors and poorly made parts that they needed at least 2 hp motors to move this needed 800 CFM. Sadly, one lower cost import vendor did not move 800 CFM even with their 3 hp dust collector.
No vendor moved the 900 CFM or 1000 CFM needed to meet the higher air quality standards with a dust collector powered by anything under a 3 hp motor and 14" diameter impeller.
Most larger and inexpensive dust collectors come with 30-micron bags that are ideal for venting outside. By definition airborne dust particles are sized under 30-microns so this size filter passes close to 100% of the airborne dust. When vented outside airborne dust vanishes with no visible trace. This also means we spend minimum time cleaning filters and get maximum filter life. Of course this open of a filter should never be vented inside. Unfortunately, almost all small shop dust collectors are built so they cannot handle weather so they need to be put in their own separate room that has appropriate fire and explosion protections.
We found no dust collector that came with bag filters suitable for venting indoors. Medical experts recommend at least MERV-15 or better filters and most of the filters we tested rate at far below with filtering efficiency that freely passed the unhealthiest under 10-micron sized particles. All stock fine bag filters measured with about one tenth the overall surface area recommended by fine filter makers. The newer cartridge filters mostly had less than one half the recommended surface area. These cartridge filters mostly claimed 0.5-micron separation but tested with only 5-micron separation.
All of the dust collectors with canister cartridge filters had problems. Many consider me to be one of if not the expert on cartridge filtered dust collectors. I invented these many years ago and now just about every small shop vendor offers their own variations. The cartridges offer far more surface area than the standard bag filters so can provide finer filtering with much better airflow and lowered resistance. Most still provide way too open undersized cartridge filters that pass almost all of the unhealthiest invisible dust. Undersized cartridge filters quickly load up and soon block the airflow needed for good collection. Worse, as they become fully seasoned they then permanently block so much airflow they seriously reduce collection. Most vendors also sell cartridge filters with pleats that are so close together they trap chips between the pleats. Cleaning requires digging out the larger trapped chips which quickly destroys filters. Similarly, instead of using shaking or an air stream blast which pleated filters were made to handle, almost all small shop dust collectors now come with beaters or flaps that physically hit the filter pleats. That contact creates wear points that cause our filters to quickly fail. I worked with Wynn Environmental to come up with filters that are fine and large enough to provide good filtering and with pleats far enough apart the filters don't quickly load up with sharp chips that ruin filters. These are best cleaned with gentle tapping or being blown down from the outside. If you cannot put your dust collector when it can vent outside with a good heavy 30-micron polyester felt filter, we strongly recommend using these better quality fine cartridge filters.
Fine Wood Working magazine in April 2006 magazine issue #183 published an article by Michael Standish titled "Portable Dust Collectors". I helped setup the testing protocols for this article. The testing done for this article did much of the testing I am no longer permitted to share that my scientist and engineer friends are still doing.
This article came up with exactly the same conclusions and recommendations that we reached from our ongoing testing. The below graph copied from this article is easy to read and tells us which machines move ample airflow and the answer is none if you are serious about good fine dust collection. Anything above 350 CFM and below the 800 CFM line is a good "chip collector", so this graph confirms every dust collector tested provides good "chip collection". Because the testing for this article was done using a consistent filter that was already "seasoned" we do not have to worry about the overhead of the dust collector or its filter, but only the resistance of our ducting and tool hoods. A good static calculator shows that this overhead resistance averages about 2.3". Looking above the 800 CFM line and to the right of about 2.3" of pressure tells us which dust collectors move ample air at ample pressure. Sadly this graph shows none of these dust collectors tested move enough air for good fine dust collection as that requires a full 1000 CFM or more airflow at this resistance level. Only the Delta, Grizzly and Jet dust collectors that this article rates as "excellent" barely moved the 800 to 900 CFM airflow required to meet the OSHA air quality guidelines and none moved the 900 to 1000 CFM required to meet the ACGIH air quality guidelines. Frankly, years of testing shows we really need one of the better quality 3 hp dust collectors if we want to get good fine dust collection with a full 1000+ CFM at most small shop larger stationary tools.
In addition to moving ample air, fine dust collection also requires either blowing the fine dust away outside or ample filtering. None of these portable dust collectors had the minimum MERV-15 (0.3-micron to 0.5-micron) filters recommended by medical experts. All came with under 30 square feet of filter area instead of the at least 500 square feet recommended by filter makers for fine filters. All three of the "excellent" rated dust collectors have enough pressure to power a 5" horizontal main and 4" down drops which will provide good chip collection in most small shops. None generated enough pressure to support the 7" mains and down drops needed to move the full 1000 CFM for good fine dust collection. I believe the only safe way to use any of these dust collectors is to place it and vent them outside with no air returned to our shops, while working with a strong fan blowing through our shops and wearing a properly fit dual cartridge NIOSH approved respirator mask.
Decades ago Delta started producing a standard small shop cyclone. Discussion on the woodworking forums said Delta built this cyclone from the scalable free plans that the New York Dept. of Labor, Division of Hygiene Engineering published in August 1962. Delta equipped the same size cyclone with different sized blowers to meet different small shop needs. These and the copies sold by almost every small shop vendor with a less than 3 hp blower provide the roughly 350 CFM that most small shop stationary larger tools require for good chip collection. When put outside and vented outside with a 5 hp or larger blower these Delta cyclones provided excellent chip collection to three or more small shop stationary large tools running at once. Delta offered a variety of larger blowers and motors that worked with this same sized cyclone. I have seen advertisements for up to 12.5 hp motors, but people have written me saying they had up 15 hp motors on their Delta cyclones. Rather than include the high expense for automated bin emptying systems and self cleaning filters, Delta equipped their small shop cyclones with big 30-micron bag filters. A 30-micron filter freely passes the airborne dust while trapping the odd pieces and missed dust. When the dust bin gets all cyclones push everything right through the cyclone and the blower. This is why our cyclones have to have big heavy NFPA approved impellers than can handle material hits. The big 30-micron bag filters that Delta used trapped that dust rather than making a huge mess. Delta was very clear that these cyclones needed to be vented and put outside behind suitable fire and explosion proof barriers.
That New York State scalable cyclone plan is actually a basic agricultural cotton cyclone built with very high internal turbulence to break sand and dirt apart from cotton fiber. When used for woodworking these agricultural cyclones do an excellent job of "chip separation" breaking the airborne dust from the heavier chips and sawdust. This design depends upon gravity to drop the heavier sawdust and chips but have so much internal turbulence they simply blow almost 100% of the airborne dust particles right through the cyclone. On average by weight woodworking dust is made up of about 85% heavier chips and sawdust plus about 15% airborne dust. By definition airborne dust particles are sized under 30-microns and do not readily settle in outdoor air currents so when vented outside they vanish with no visible trace. All cyclones work with a strong updraft. This updraft sucks strings, long shavings, threads, hairs and other odd shaped pieces with an air profile that acts like a sail or parachute right through the cyclone. Further, most traditional cyclones also fail to separate off about 1% of the heavier particles due to changes in airflow and internal turbulence. These odd shaped pieces and missed dust make up less than 3% of the total weight of debris created by woodworking. This 3% is so little material it rarely is seen and causes no problems when vented outside. So, when we add the 15% airborne dust, 2% odd shapes, and 1% random passing the best that traditional small shop cyclones should provide is about 82% separation efficiency. The two very squat fat looking cyclones which I am not allowed to name use their own unique design. Theses units were magazine tested to separate much worse than a trashcan separator and even most dust collectors.
Small shop vendors saw the success Delta had and wrongly assumed they could simply make their own copies of this same cyclone design. The small shop vendors did a terrible job on their copies. Many carefully measured the different small shop cyclones and found all but two to be fairly close variations of that same basic design. Most changed the cyclone cone to force fit the cyclone system under a standard eight foot tall ceiling. Their not holding to the original design ratio resulted in the cyclone cones frequently plugging, and the cyclones suck the debris right out of the dust bins. Most also changed their cyclone inlets, dust chutes and cyclone outlets to connect with existing blowers, ports and dust collection components. These changes combined with shoddy construction to make most small shop cyclones very inefficient both in terms of how much air they can move and how well they separate. Most lose about 1/3 of the airflow that dust collectors with identical sized blowers move. Instead of the expected roughly 82% cyclone separation efficiency most get less than 80%. Adding on undersized blowers on these high resistance cyclones ends up with those sized under 3 hp not moving enough airflow to provide good chip collection. And those sized under 5 hp do not move enough air for good fine dust collection.
The small shop vendors built their cyclones for indoor use. Putting these cyclones inside greatly increases our health risks. Instead of venting the fine dust away outside where it quickly dissipates and breaks down as soon as it gets damp, venting inside fills our shops with unhealthy fine invisible dust both from what these systems fail to collect and from what passes right through their filters. Small shops mostly don't have a separate outdoor room for equipment, so most small shop cyclones end up being put inside because small shops rarely get fire marshal and building inspections that require the equipment either be fire and explosion certified or put outside. Almost all small shop vendors initially configured their cyclones with 30-micron filters that were designed only for outdoor venting because they pass the airborne dust right through. This left small shops covered in dust. Rather than admit their cyclones should be placed and vented outdoors, many small shop vendors simply added finer filters. The finer the filter material the more expensive it is to purchase and the more material we need to keep the filters from plugging and killing the airflow needed for good collection. Small shop vendors upgraded to filters just fine and large enough to get rid of the visible dust. When placed and vented indoors these too open filters create a dangerous false sense of security. Our testing showed most small shop cyclones and dust collectors with less than MERV-15 fine filters were dangerous dust pumps that filled small shop air with so much fine dust that most who work in small shops get more fine dust exposure in a couple of hours than most full time workers in large commercial shops that vent outside get in months of full time work. Although advertised to protect our health they instead damaged our health. Worse, many small shop woodworkers use fairly toxic woods that cause irritation, poisoning, nerve damage, rapid onset of allergic reactions and even increase our risk of some nasal and respiratory cancers. This toxic dust often built into dangerously high levels in many small shops. I receive about one email a week from additional woodworkers who have been harmed by this fine dust.
It is no secret that the reason I came up with my cyclone design and these Cyclone and Dust Collection Research web pages is because I was badly hurt by trusting the cyclone vendor that the magazines continue to rate as the "best" cyclone provider. This cyclone vendor used and still uses a very successful fear of fine dust advertising campaign to sell expensive cyclone and ducting systems. They were so successful other vendors either bought rights to use that same cyclone design or just plain copied the same cyclone design. That left the small shop market full of "chip collector" cyclones that did a very poor job of fine dust collection.
This design had terrible airflow. The vendor assured me it could collect from three of my larger stationary tools working at the same time plus one small tool as well. It did not collect well enough to even support one tool working at a time. Even after upgrading my unit with a "neutral vane" plus the other changes I had worked out and shared on my cyclone modification web pages it still provided dismal airflow.
This cyclone provided even worse filtering. This cyclone design was never designed to provide the separation needed to work with fine filters. It should have only be run without filters and vented directly outside, which is illegal where I live. This vendor used a far too undersized filter that was just fine enough to pull off the visible dust. The result created a bad false sense of security that left my shop looking clean while it built up dangerously unhealthy amounts of very toxic invisible dust because of the rosewood, walnut, and cocobola woods I worked. This system kept that toxic dust cloud airborne which badly contaminated my attached home. The gravely undersized fine internal filter plugged every twenty minutes when using my drum sander and about every two hours during normal woodworking. As discussed before filters quickly get ruined by too much cleaning because cleaning forces the fine wood dust particles with their razor sharp edges and sharp often barbed points to cut and tear their way through our filters. The smaller the filter the more it needs cleaned so the less time it will last. To clean its too small filter every few hours of woodworking the cyclone had to be taken apart which left me and my shop covered in the fine dust I installed this system to avoid. Their bad ducting design caused that tiny filter to fail immediately. The ducting was so poorly engineered the large vertical ducting runs plugged constantly and the horizontal ducting runs built up huge dust piles because the cyclone lacked the airflow to keep the ducting clear. The piles posed a fire danger and when airflow was restored these piles slammed down the duct so hard they blew apart my ducting joints, went right through the cyclone, ruin the impeller, and then blew apart the fine filter. Frustrated from ruining expensive filters, I did as their engineer recommended and used his recommended big third party fine filter bag. That was a terrible solution as their system blew on the side of the filter, so the frequent dust piles slammed into the filter hard enough they blew a hole in its side. Clearing the constant cyclone plugs in the cone also required taking all down which added more mess. Two and a half months after installing this system I decided to get rid of it and buy a used commercial system.
Regardless of my following my cyclone vendor's instructions and making their suggested upgrades, three months after installing that cyclone and vendor provided ducting with the improved fine external filter I landed in the hospital with a nasty allergic reaction. It so shut down my airflow I nearly died and the dust trapped in my lungs created so many bouts of pneumonia I lost over half my lung capacity. When I was not getting better my doctor talked me into paying for expensive medical air quality testing. Three months after I stopped woodworking, my shop and home still were badly contaminated. My inspector's tests showed my cyclone at most moved less than half the air required for good fine dust collection for my largest down drops and under one tenth the needed airflow for the smallest down drops my vendor designed. He found its upgraded filter freely passed the invisible under 10-micron particles known to cause the most damage to our health. He was pretty upset by the very poor quality of that system that lacked the airflow to keep the ducting clear, provided no better separation than the trashcan separator lid it replaced, and my vendor totally "forgot" to advise me of the need to upgrade my tool hoods so even had the cyclone worked with ample airflow there was zero chance of my shop having the good fine dust collection they advertised.
So from that vantage, none of our cyclone test results surprised me. The same dismal test results on the expensive "best magazine rated" cyclone system I installed gave near identically dismal results which is what inspired me to come up with a much better cyclone design and to create these web pages. Clear Vue Cyclones sells cyclones that use my scalable improved cyclone design which is on these web pages. Our tests of my design were also independently done by four different university medical schools. All results came out near identical. That testing showed my cyclone without filters separates 99% of the total weight of all particles sized 30-microns and larger. To this my cyclone design also separates 99% of all particles sized down to under 5-microns, over half of the weight of even finer particles plus over 88% of the odd shaped particles that go right through traditional cyclone designs. The bottom line is my design sold by Clear Vue consistently tested with its dust bin holding over 97.3% of the weight of the dust produced. My cyclone design only puts about one eight as much of these odd shaped pieces into the filters. Where my cyclone design excels is it it consistently separates off most of the airborne dust. Instead of putting at least 17% of the dust by weight into the filters, my design tested consistently at only putting under 1.6% of the overall dust by weight into the filters. This is why my design is now used by over 10,000 small shop owners worldwide. This also explains why Clear Vue cyclone owners often only have to clean their filters every few months and why their fine filters last years instead of months. The consensus among the test group is my cyclone design is the only one they recommend using with indoor venting and fine filters.
All cyclone vendors except Clear Vue gravely misrepresented the separation ability of their cyclones and filters. Our tests showed all small shop cyclones except for the Clear Vue units provided less than 83% overall cyclone separation by weight. As with our other filter testing we found most earlier filters only separated down to only about 10-microns. That meant these systems filtered off the visible dust and freely passed the invisible dust which makes up about 5% of the average dust produced by weight. This resulted in most systems then having less than 95% overall efficiency. Today many vendors have stepped up to now include finer filters standard with their cyclone systems. Most vendors now include real 5-micron filters so get about 96.5% overall separation by weight. Those who have stepped up to MERV-15 filters are now getting close to the 99% separation by weight that they advertise. Every 1% of the under 10-micron sized dust missed puts enough fine dust into the air to cause 151 typical two-car garage sized shops to fail an EPA air quality test. When vented inside this dust lasts nearly forever unless it gets wet, so systems with more open filters do not protect our health. Unfortunately these systems have such poor cyclone separation they still load the filters with about 17% of the total weight of the dust produced. At these dust loadings, most commercial shops find they have to clean filters roughly every two hours and must replace their fine cartridge filters roughly every three months of full time use. That high cleaning load, short filter life, and poor fine dust separation resulted in our recommending the best way to use these traditional cyclone systems is to simply throw away the filters and vent them directly outside. Otherwise you need to work wearing a good dual cartridge NIOSH approved respirator mask and a strong fan venting out your shop.
Those with finer bag and cartridge filters almost all advertise 1 to 2-micron filters. Many of these claims for fine filtering come from the same few vendors that falsified their maximum airflows. Filters pass a range of dust particles that cycles from a maximum when new and clean to a minimum when the filter is fully loaded with an internal cake of dust in the filter fibers that increases filtering. For dust collection this creates a swing of roughly twenty fold between the highest and lowest filtering provided. Most small shop dust collector "fine" filtering bags and cartridges were advertised with their maximum filtering between 0.5 and 2-microns meaning their maximum varies between 10 and 40-microns. This leaves these filters passing almost all airborne dust when new and still passing almost all of the finest unhealthiest 2.5-micron dust the rest of the time, clearly not filtering suitable for breathing. Although the dust collector makers came out with better filters, they are still shy of what we need to bring these units down to a more healthy range.
We found no dust collectors or cyclone systems with ample fine filter surface area ample to match industry standards. When fine filters are made too small they quickly plug creating constant cleaning problems. Cleaning destroys the filter pores soon opening them to also make even the fine filtered dust collectors into "dust pumps". The only way to use these units for fine dust collection is to put them outside with no air being returned to the shop. A 0.5-micron fine bag or cartridge filter at 800 CFM airflow and the relatively "dirty" air from a dust collector needs at least 200 square feet of area but typically come with less than 30 square feet, many with just a top bag only have 15 square feet. Using a smaller filter works for a short while but soon causes undersized filters to fail from too much dust loading and excessive cleaning. Those offering cartridge filters typically offer the poly-cellulose blended filters that require roughly double the surface area as the all poly felt, so also provide less than a quarter the needed filter area.
- Blower Testing
Although many choose to use smaller dust collectors, small cyclones, and other options, the bottom line is you need to move enough air to capture the fine dust at the source, use good hoods, and then preferably blow the air away outside or provide ample filtering. Most small shop dust collectors and cyclones are challenged in airflow ample for good fine dust collection. Most dust collectors, cyclones, shop vacuums, and air cleaners tend to have too open filters to safely vent indoors. Most dust collectors and cyclones also compromise on filter size. Although smaller filters work, the trade off is far more cleaning, poor airflow and need to constantly replace our expensive fine filters.
Today I believe small shop owners have more and better fine dust collection options, but most small shop vendor supplied dust collection systems still have lots of issues including insufficient airflow, poor separation, filter plugging, filter cleaning, poor filtering, filter replacement, cyclone cone plugging, sucking the dust out of the dust bins, building up dust piles in the ducting, on and on. Concerns with airflow requires we purchase at least 3 hp dust collectors and 5 hp cyclones to get ample airflow for good fine dust collection. Concerns with poor separation means most small shop dust collectors and cyclones should be used with 30-micron filters that we vent inside, or we need to step up to finer separating cyclones. Feedback from owners of these various cyclones almost always started off as excellent, but as their cyclones and dust collectors got used their often far too small filters season which makes for constant filter cleaning, frequent filter replacement and insufficient airflow to provide either good fine dust collection and often even good chip collection. Many found in their own use these same concerns and raised these issues with their vendors. Most said the vendors passed these concerns off blaming poor user poor testing, bad setup, or not understanding the physics and proper testing protocols. Frankly, as a group the whole bunch of small shop vendor supplied dust collectors and cyclones would gravely fail to measure up if the US adopted the much more stern new European air quality standards. Today only the top few actually keep the fine dust levels amply down enough to pass the now dated OSHA air quality standard. With most dust collectors and cyclones actually increasing the airborne dust levels, I continue to only recommend all dust collectors and cyclones except my design be vented outside instead of into fine filters. Here are summaries of comments made by the owners of these few units.
- Traditional Cyclones
The largest small shop cyclone producer copied the 1962 New York State scalable cyclone plans. They built a very successful advertising campaign selling this cyclone with very fine filters promising health protections that they cyclones had neither the airflow, ducting design, nor filters to provide. They achieved so much financial success that two other major small shop vendors hired the original vendor and ended up with identical cyclone designs. All other vendors except for two then simply copied this same design resulting in all small shop cyclones except for two being variations on the same 1962 design.
Unfortunately, the initial vendor copied that original scalable design then simply changed to a shorter cone to force fit the cyclone overall size under an eight foot ceiling. Their modifications caused me and all who buy the variations of this design problems. I was one of the many who bought and was badly burned by my magazine top rated cyclone. It plugged the filter after every few minutes of use, required taking the cone off to clean the internal filter, and every disassembly left me and my shop covered in the same fine I installed this unit to avoid dust. Although advertised as a 1200 CFM machine that would concurrently collect from three large and one small tool all running at once, it barely collected from just one tool running at a time. Its maximum airflow was well under half the advertised airflow and its vendor designed and supplied ducting dropped the airflow on my smallest down drop to under 32 CFM. That 32 CFM left the air in the huge main duct moving so slowly my ducting main constantly plugged in a short vertical main run near the cyclone and the horizontal runs built up huge piles. When airflow was restored these huge piles slammed down my ducts at over forty miles an hour and hit the ducting joints hard enough to blow my fittings apart. Worse, these piles slammed so hard into the fine filter they ruined it within days. Frustrated I called the vendor repeatedly until the fellow who claimed to be their senior engineer finally admitted this cyclone which they sold to all small shop woodworkers who only used one tool at a time was gravely undersized and the putting the cartridge filter into the cyclone outlet, an innovation from their president was a nightmare. He told me to rip out the internal filter, replace it with a custom bag his firm was having a third party make for the many disappointed customers, and if that was still not enough I would need to buy a bigger blower or whole new cyclone. After making the filter change, that changed filter was quickly ruined by the air blasting too much dust including the big piles that went right through the cyclone. I decided to junk that system and upgrade to a used commercial cyclone.
I instead landed in the hospital. Allergy testing showed I had become severely allergic to various woods and medical air quality testing on my shop showed my my shop with more than double the airborne dust allowed by OSHA with airborne particle counts thousands of times higher than considered medically safe. My cyclone lacked the airflow to capture most of the fine dust. My vendor failed to tell me my stock hoods were worthless at capturing most of the fine dust. Both the vendor supplied internal cartridge filter and the third party upgrade they had me buy were open sieves that pushed most of the fine dust right through. I spent my months of recovery time gathering suggested upgrades then using the labs at the university where I taught engineering to test and refine the various suggested modifications to make that expensive cyclone viable. I was able to improve airflow by about a third and improve separation by about a third. I shared the results on my Cyclone Modification pages. Eventually I realized that basic design that all still use needed either vented outside or scrapped. With local problems preventing me from venting outside, I needed a better cyclone. The issue is wood gets much of its strength from silica better known as glass. This means fine wood dust is made up of a high amount of ground glass. If a cyclone does not separate off most of this fine dust before it gets to the filter, that filter will soon be history. As the dust accumulates plugging the filter the air pressure climbs enough to force these fine particles to cut and tear their way through the filter. Worse, cleaning just accelerates this filter breakdown, which is why commercial firms use filters with lots of area and clean with fairly gentle shaking.
Clear Vue & My Cyclones
I started by going back to the basic cyclone physics then came up with a few novel innovations of my own. The cyclone I designed and shared on my web pages rapidly evolved into a very efficient separator which is what cyclones are for. The result worked incredibly well with my university and two other universities rating my cyclone design at 99.9% effective at removing particles sized 5-microns and larger. The closest competition as of the testing done in late 2006 is a cyclone with all the changes from my Cyclone Modifications pages providing 99.9% separation efficiency on particles sized 22-microns and larger. All who have built or bought one of these cyclones of my design swear by them. A few swore at me during the building process because you trade a lot of time for not too much savings. In spite of some grumbling on various Internet woodworking forums, building your own cyclone from my plans or a kit is a very cost effective alternative. If you are patient and have about 20 hours total time, this design offers the best performance available for less than the cost of a good 2 hp dust collector.
After too many complained that building their own from my plans was too difficult I also licensed my design for commercial sale in kit form in trade for a small royalty fee to offset the growing costs of maintaining these web pages. After three attempts to let others build my design did not work out and my health precluded helping my young son to make kits, I moved on. Sadly, a few others without my blessings still sell copies of my design without my permission or support, plus most of the vendors now copy portions of my design from my Cyclone Modifications pages. Please do not support these firms as they neither acknowledge my work nor pay me anything for my efforts, plus they send their customers with problems to me for help.
In 2004 Ed Morgano and his son Matt followed the plans on my web pages to build one of my cyclones because they were getting ill from the huge amounts of dust being created by their CNC based MDF routing business that made cabinets. Ed was very pleased at how incredibly well this unit worked after everything else they had tried proved to be nothing but advertising hype. Ed was a machinist who specialized in working with plastics. He built another of these units in clear plastic to have a clear view of what was going on inside. He showed off that unit on a few of the CNC forum pages. He was immediately asked by many people who wanted him to build a clear cyclone. Ed asked my permission to build these and agreed to pay me a small royalty payment on each unit sold for using my design. I gave Ed my permission and lots of my time to help support his business. Although I own no part of this firm, do not manage it, and am not employed by them, I wish I did own a portion of this firm as they did very well. With just the free small ad on my web pages and making sure each unit is well built and providing excellent customer service Ed and Matt quickly built this Clear Vue Cyclone firm into one of the top suppliers of small shop cyclones in the world. They did so well that their main competition who built the cyclone that landed me in the hospital went back to their old tricks putting up falsified performance comparisons on their web pages along with filing nuisance law suits that had no merit, but waste lots of time and money. They even paid shills and forum administrators to flood the various Internet forums with all kinds of falsified information about Clear Vue Cyclones, their management and their products, plus about me. Those claims are the same nonsense this vendor has been spouting since their fear based advertising campaign was proven to be a hoax back in the nineties. Regardless of all that negativity, Clear Vue grew to be the largest provider of small shop cyclones and the unit that most prefer. Unfortunately Ed's health failed and the worsening economy left him unable to find a buyer for his firm. Ed closed Clear Vue Cyclones. Later it was purchased and restarted so is now rebuilding its business again with my support and help.
WoodSucker is no longer be in business but its founder Larry Adcock deserves high praise for helping to change the dismal shop dust collection market. The 2000 U.S. Census shows six out of seven professional woodworkers work in small shops as do almost all hobbyists. These shops are mostly not subject to either fire marshal inspections or air quality testing. Most of the mass marketed import firms sold smaller indoor copies of commercial dust collectors and cyclones that had to be kept outside to pass fire marshal inspections. Bringing these units inside was building up huge amounts of fine airborne dust with the typical shop according to OSHA testing running two to five times more than the maximum allowable airborne dust levels. OSHA air quality testing was only required of the largest commercial woodworking facilities, so most of this market continued to use dust collectors and cyclones that only did "chip collection" meaning collecting the sawdust and chips amply to pass fire marshal inspections. With the small few person woodworking shop market collapsing due to pressure from large manufactures and off-shore competition, one of the cyclone suppliers to these small firms that only did "chip collection" developed a strong fear based marketing campaign. That campaign warned all small shop woodworkers that inhaling fine dust is very unhealthy, and they offered up their "chip collecting" cyclone with a fine cartridge filter stuffed inside the cyclone outlet as the ideal solution. The woodworking magazines gave this unit high praise, but the newly emerging Internet woodworking forums were a totally different story. Many high end woodworkers are very capable people with a wide range of skills who often have the money to buy top quality equipment. The many of these people who bought this cyclone setup with ducting to protect their health found adding the cyclone made things worse. Those with test meters began doing some testing and suddenly this top magazine rated cyclone vendor was in deep trouble. Their cyclone was a fraud. The filter did not work. Their free ducting design they gave away to entice people to buy their triple the normal priced ducting and cyclones did not work. Their supposedly airfoil impellers were simple very inefficient backward curved impellers. Their filter was a fraction as large as the filter makers said it needed to be to handle the airflows and dust loading. In short the many dozens if not hundreds who fell for that fear based advertising campaign were badly burned, upset, and telling others of their frustration. Instead of fixing their terrible products, that firm used their advertising might to attack and get those who were critical banned from the various forums. Quite a few bright people went to work trying to figure out how to fix these very expensive but dismally performing cyclones.
Larry Adcock was one of the first to recognize that the whole approach of simply downsizing a big commercial cyclone and dragging it indoors was not viable. Larry is a pretty competent fellow who went to work doing the engineering to design a better cyclone. He started with the roughly 40% efficient blower and upgraded to a caged impeller design that is nearly twice as efficient. This let him move more air with a 2 hp motor than most could move with anything less than a 5 hp motor. He then incorporated the neutral vane to decrease performance robbing internal turbulence, and further improved separation efficiency with a helical air baffle better known as an air ramp. This ramp directs the air into a spiral and reduces internal turbulence. Larry opened a small shop and began offering his "WoodSucker" cyclones for sale. WoodSucker soon became the target that other small shop cyclone vendors tried to match. The pricing and performance for the WoodSucker sparked a whole new series of better performers. Larry developed a long backlog on orders with Internet forum posts consistently praising all but the noise and sometimes fit/finish. Larry responded to the few concerns about his units by greatly improving the fit and finish with his WoodSucker II. Owners consistently give that unit very high praise in all areas. Further, it came complete unlike most of the competition that needed filters, hangers, power cords, etc.
My look at this unit showed it built like a tank and a solid performer for a small shop with normal ducting. In looking over the WoodSucker II design and airflow curves, this was the strongest available cyclone for its size motor. Because of its impeller efficiency it was the only 2 hp cyclone I would consider and it was a unit I recommended. I only recommended it for smaller 1-car garage sized shops because even it did not move ample air to handle larger shops. Unfortunately, the same vendor whose dismally performing cyclones inspired the WoodSucker, came back on the attack. As a major advertiser they paid for a magazine to run a just plain bad test. Instead of rating cyclones with real ducting on how well they collected and separated the heavier and fine dust, this magazine test only evaluated on total airflow. It takes a lot of work to force air into a tight separation spiral in a cyclone. As a result, most cyclones use oversized blowers to overcome this high resistance. If you can take away that resistance, then these blowers will move over double the total airflow that they will move when in real use. This upset vendor put absurdly oversized inlets on their cyclones and had their magazine testers do the testing with pipes sized the same as the inlets. With most using 6" diameter ducting, the WoodSucker used a 6" inlet. The resulting testing showed the WoodSucker to be one of the worst performers of all the units tested when in real use with standard ducting it is actually one of the best. Regardless, most do not take the time to really do their homework and tend to believe their magazines. What did not get out is a number of motors burned up from trying to push too much air in the top rated cyclones. Regardless not too long after that dismal review came out WoodSucker stopped answering its telephone and email.
Felder RL Dust Collectors
All of the cyclone problems reopen the idea of just buying a top quality dust collector. There are not many choices. Of all the dust collectors I reviewed prior to 2005 only the Felder RL-160 Series Clean Air dust collector actually moved ample air and provided the filtering to make it a good indoor fine dust collection system. I presume their newer even larger RL-200 would perform even better. Since my original review Felder changed its RL-125 dust collector pictured to the left to also move ample air for good fine dust collection. Unfortunately, the feedback I've received from those who have tried this smaller unit, say it really is too small both in airflow and chip capacity. Those with the money rave positively about their new clean air Felder RL series collectors that provide a staged fine dust filtering setup to be suitable for indoor use. Some of the Felder RL dust collectors come with a muffler as standard equipment. Although the maker claims these units have the capacity to run more than one machine at a time, the RL-125 specifications show it clearly does not and the RL-160 looks marginal to run two larger tools concurrently. The price tag on these units was very acceptable for when I owned a shop and cheap for those with respiratory problems. I asked John Renzetti who uses one of these Felder units to share a little review. Here is what he shared.
Felder introduced the RL series dust collection system in 2002. The development came about as a result of much stricter standards for emissions in Woodworking shops in Germany. The German health authorities found a high rate of nasal cancer especially in those shops that returned the air directly to the shop. Felder submitted the machine to the German Government Health department for certification as a clean air dust extractor, and received approval from the BG test authority. The ratings put out by Felder are from these tests, which tested emissions and CFM of the machine with dirty filters, and flex hose with 90 degree bends.
Dust and chip laden air is drawn into the intake port. Vacuum pressure pulls the heavier chips down into the bin, while the dust-laden air is pulled up through a bank of HEPA type filters. The clean air is then pulled through the fan blower and exhausted. The cost of the RL dust collectors will probably put them beyond the budget of most hobbyist shops. The RL125 is around $2000, while the RL160 is close to $2500.
- Traditional Cyclones
Less Viable Options
Although many choose to use smaller dust collectors, small cyclones, and other options, the bottom line is you need to move enough air to capture the fine dust at the source, use good hoods, and then either exhaust the dusty air outside or provide ample filtering. The only other viable options for good fine dust collection must move the required air and provide good filters. The trade off becomes how often we have to replace these expensive filters.
We found no bag or cartridge type dust collectors in our testing that moved enough air to provide good fine dust collection and had ample filtering to be suitable for venting indoors. The 3 hp and larger dust collectors work well for good fine dust collection it you put them outside and vent them outside with no air returned to your shop. If you choose to use a smaller dust collector, please use a good upgrade fine filter such as provided by Wynn Environmental and work with a strong fan blowing the dust out of your shop.
The simplest two stage dust collection system uses a trashcan separator lid and these work well for "chip collection" but poorly for fine dust collection. They can keep wood from beating up your filters and protect your dust collector impeller. I had many years of excellent service from my simple Woodstock (made by Grizzly and sold by many) plastic garbage can lid separator, but did have to seal the hoses and add insulation foam to seal the lid to the trashcan. Sadly, my separator totally failed to work when I upgraded my dust collector and began using larger hoses. With the 4" hoses going to it, the trashcan separators work fine. When I went to 6" hoses the additional airflow simply simply emptied my 40-gallon trashcan of all but largest blocks. You can still make something that will work but the result needs a 5' 1" diameter trash can that stands about 7' tall to work with an 800 CFM airflow and to work with a 1000 CFM the trashcan ends up being much taller than we can fit under standard eight foot tall ceilings. I've done a lot of experimenting with cyclonic separation tops and they work better, but generate even more resistance than a cyclone. Many of us are still working on a viable solution that will work with a high airflow and still be as easy to use and empty as the trashcan.
Small Shop Cyclones
Most small shop cyclones are designs taken from outdoor commercial cyclones that barely move ample air for good "chip collection" and separate very poorly, so remain a poor choice to bring indoors or use with fine filters. The worst cyclones are add-on units that attach to existing dust collection blowers. These add-on cyclones add so much overhead they kill the airflow needed for "chip collection" saying nothing of having no where near the airflow needed for good fine dust collection. The basic cyclone design and engineering for almost all small shop cyclones requires a 2 hp motor for "chip collection" and a 5 hp motor for good fine dust collection. Use of a "neutral vane" and the other changes suggested on my Cyclone Modification web pages can increase efficiency considerably, but not enough for most vendors. Our testing only found one 3 hp cyclone that would actually move the 1000 CFM needed in a small shop with minimum overhead resistance. If you toss the indoor fine filters and replace them with big free flow filters with the air directed outside, these make excellent find dust collectors. Otherwise, they just do not provide ample separation, airflow, and filtering for indoor use.
There are a number of cyclone plans being sold that are all copies of the same basic "chip collection" cyclone designs. Although recommended for use with fine filters, they units quickly destroy fine filters so at best provide a false sense of security. They also mostly call for tiny blowers that only move enough air for "chip collection". With the changes on my Cyclone Modification pages and a big enough blower these do make good fine dust collection cyclones again if you direct the air outside instead of trying to filter it amply for returning indoors.
- Dust Collectors
- Small Shop Dust Collection Product Overviews
Frequently Asked Questions (FAQs)
Bill, I much appreciate the considerable work you have done to help woodworkers better protect their health, but you have given me far too much. I don't have the time or patience to read through and understand all this. I have just converted over my two-car garage to a shop and just want four simple dust collection questions answered. - Lou
First, many of my family members and friends have all done woodworking for ever and nobody has ever gotten sick. Just how serious is this fine dust problem and is it worth investing the money to provide extra protection for my family and me?
I truly hate answering this question over and over again. Not only have I gone to considerable pain to cover it in more depth than most ever want to hear on these web pages, this question forces me to try and be objective when I really want to just kick some sense into woodworkers who don't realize they are putting themselves and those close at serious risk. Please re-read the Medical Risk pages.
What are the minimum requirements I should look for in deciding on what dust collection I need? Air engineers did considerable testing and shared what they have learned about fine dust collection since the 1950s as to what it takes to address the fine airborne dust problems. Please reread the Best Practices section above then if you have questions of more detail read over the Dust Collection Basics page. Here is a quick summary.
First, fix our tool ports and hoods so they do not spray the dust away before it can be collected.
We then must provide ample airflow at each machine for good fine dust collection.
We must upgrade our ducting to ensure moving ample air.
Then preferably vent the dust air outside where it cannot be blown or sucked back into our shops. If you have to filter, then you should use amply fine at least MERV-15 filters and either buy or build a cyclone of my design to keep those filters from constantly loading up, rapidly failing from too much cleaning, and to maximize filter life.
I fully expect to follow the footsteps of my father and grandfather starting my woodworking hobby modestly with a good set of hand tools then as I get more proficient adding a few stationary tools in the basement, and eventually building a dedicated shop. I suspect most go through a similar progression. How should I manage the fine dust during the growth of my hobby? For new woodworkers I recommend starting woodworking as a fair weather activity where we work outside wearing a good certified NIOSH dual removable dual cartridge mask when making fine dust. I use a 3M half mask in my size from a local hardware store that stocks a range of filters allowing me to also use this mask when painting and spraying my garden. This lets us get going without a huge cost in tools or putting our health at risk. The basic tools will be useful around the home even if woodworking turns out to not be a long term hobby. I now personally do quite a bit of my work outside using a good hand held power saw, router, jig saw, drill, orbital sander, and oscillating spindle sander with a guide system instead of my large stationary power tools. I find I can do all just as well, with far less setup, and considerably more ease especially when working with large sheet goods. Festool probably makes the nicest of these type systems and other vendors offer a range of similar offerings. I personally use the Eureka Zone EZ-Smart guide system and table. This system is so versatile my daughter and I made her a nice desk in the fall of 2005 without doing any machining or sanding indoors.
Most work indoors and end up getting at least two dust collectors before upgrading to a cyclone system. If you have a garage attached to your home or worse, a basement workshop like yours, then I strongly recommend you work elsewhere where you will not contaminate your home. Otherwise you should start with getting a good Dylos Products Pro particle counter and install ample fine dust collection to protect your home from being contaminated. The best way is to vent outside. I recommend use of infrared heaters in your shop and blowing the dust away outside ensuring that you provide ample make up air to keep from drawing deadly carbon monoxide backward through your vents, stoves, and fired appliances.
And finally, like most I am supporting a family, so have serious financial constraints on my woodworking expenditures. I also want to end up with good quality equipment that will last. How do I manage this dust safely without breaking the bank and will you recommend specific brands and models for each phase of this adventure? If you will not work outside, I still suggest you buy or make a cyclone that you vent outside. The cost to build your own is about the same as a typical dust collector ample for your sized shop, and will save you having to go through the two or more dust collectors that most of us have to buy before waking up. I personally kept my Jet 1.5 hp dust collector because it is a well built unit and with my DC Cartridge Conversion works great for quick jobs where I don't want to turn on the cyclone. At the same time, I know this unit pumps too much dust into the filter that I need to wear my respirator and change that filter frequently to keep myself protected.
Bill, I have a small 2-car garage sized shop with no ducting, what dust collector should I buy? I don't recommend buying any dust collector, but if you have to please ensure it moves enough air for good fine dust collection, that you use ducting to put that unit outside where the fine dust cannot blow back indoors, and that you use fine open filters that flow the most air to provide the best collection. Also, be aware that many vendors either lie or advertise exaggerated airflows. The best two 1.5 hp dust collectors are made by Jet and Delta, yet neither of these generates ample pressure to overcome the normal resistance to power the ducting in your two-car garage sized shop plus the resistance of your dust collector filter. For good fine dust collection your shop needs one of the better quality 3 hp or larger dust collectors to provide ample airflow. One caution here, please don't get sucked in by false advertising that offers 2 hp and larger dust collectors that plug into a standard 120V plug. Some vendors play games rating their motors based on starting amperage instead of working amperage so call 1.5 hp and smaller motors 2 hp to as much as 6.75 hp.
Bill, you have me confused again. You say we need 800 CFM in one place as a minimum yet in other places recommend at least 1000 CFM at our larger tools and dustier woodworking operations. How much CFM do you recommend? Air engineers have spent over fifteen years refining their tables that show the minimum airflow needed to provide the collection at different tools ample to meet the different air quality requirements. Since most large tools in small shops are identical to smaller commercial tools, we can use these same tables. CFM requirements tables for our tools to meet the medical air quality requirements already in use in Europe are not yet available, but the testing shows we either need tools built from the ground up to totally contain the dust as it is made or that we need about 1000 CFM at most larger hobbyist tools and dustier operations. Most small shop tools get OSHA air quality with 800 CFM, ACGIH air quality with 900 CFM and EPA air quality with 1000 CFM.
What cyclone do you recommend? In six years of testing I never saw a single small shop cyclone other than the WoodSucker II and the Clear Vue Cyclone using my design that provides good enough separation to be used indoors with fine filters. Only my cyclone with at least a 5 hp motor and blower with at least a 15" diameter impeller and a set of the larger Wynn Environmental "Nano" filters both moves enough air and provides the separation efficiency needed for good fine dust collection and protection. So if you want to filter, you should build a cyclone of my design or buy one from Clear Vue. If you can vent outside than just toss the filters and any of the 5 hp or larger cyclones will work well for small shops that only run one stationary large tool at a time.
You confused me with your blower fan tables. On one hand you recommend use of a 5 hp motor to power your cyclone, but the fan table says I need 7.5 hp and you say elsewhere that I can get by in my average sized shop with a 3 hp cyclone. How much motor do I really need for my cyclone? How about I answer this question with a question, how big enough of a motor is needed to power my car? The answer is the same it depends upon the size of car and its use. A typical chip collection cyclone that is a copy of the original Delta outdoor cyclones that most vendors copy needs roughly a 5 hp motor. Even with all the changes suggested on my Cyclone Modifications web page that many vendors have copied often without giving credit for this work, the best resulting cyclone still shoves most of the overall airborne dust into the filters. This quickly kills filters making these units in my opinion inappropriate for indoor use with filters, so I only recommend the use of other cyclone designs if you blow the air directly outside with no filter.
Perhaps the most popular dust collector available today is the very inexpensive Harbor Freight 2 hp dust collector. Can I use one of these sitting outside my shop for good fine dust collection? Can I later use this same motor and blower to power a cyclone? When that dust collector first came out I tested it thoroughly, did a long write-up on it that was shared out on a number of Internet sites, and then upgraded those write ups a number of times as this unit evolved. It started as a piece of junk with innumerable initial failures, but Harbor Freight made good on the units that failed and fixed the many problems including putting on a much better motor, better impeller and better blower housing. It is still only a 1.6 hp dust collector that moves at most 1100 CFM but in real use when challenged by our tool hood, tool port, short length of flex hose, and seasoned filter it only moves about 785 CFM. That is too little for good fine dust collection as a dust collector and severely lacking in power to meet the much higher demands of a cyclone. Doing a fine filter upgrade as recommended on my DC Cartridge Conversion page helps lots, but it is still underpowered.
Bill, you have me really confused and seeing things. I read over both the American Woodworker and Wood Magazine Cyclone & DC Testing and just about every cyclone they tested goes well over the 800 CFM that you require. They also generate far more pressure with a 2 hp motor than you say is needed for a 2-car garage sized shop with ducting. They clearly label the ducting overhead on one of the charts. Do you agree they move enough airflow, and if not why not? This is one of those questions that does not make my day. No, those reviews use test conditions that significantly differ from real use. Specifically they test with over sized test pipe, almost no ducting, no attached tool or tool hoods, and no filters. Adding that overhead back in and you will find there is no 3 hp or smaller cyclone that will give you the airflow to do anything more than just give you good "chip collection". You really need a full 5 hp cyclone to get good fine dust collection. Here is why. If you look at a good fan table it will tell you how many horsepower it takes to move a given airflow at a given level of resistance. A typical two-car garage sized shop has an average tool resistance of 2.3", at least 3.5" resistance for the cyclone, 0.5" more for big fine cartridge filter, then another at least 1.6" resistance for the ducting for a total of at least 8". Only the top two brands actually tested with blowers that move as much air as normal commercial blowers of the same size. The commercial blower tables show that at 8" of average resistance to move a real 800 CFM you need to use a 14" diameter blower impeller turned by at least a 3 hp 3450 RPM motor with our using ducting sized at least 6" in diameter. We have decades of shared experience from those major firms who guarantee customer air quality. They and medical experts recommend moving a full 1000 CFM not just 800 for good fine dust collection. The fan tables show moving this real 1000 CFM against 8" of resistance requires a bigger14.5" diameter impeller turned by an over 4 hp 3450 RPM motor plus we must use at least all 7" diameter duct. To be able to use the much less expensive and easier to find 6" diameter duct, I compensate in my designs by using a 15" diameter impeller turned by a 5 hp motor. There is enough additional capacity in this motor that I now personally use and recommend use of a 16" diameter impeller.
We adjust for pressure by using bigger impellers and bigger motors because our direct drive motors are fixed speed. Many small shop vendors now advertise their cyclones with 14" impellers, a 7" inlet, and only 2 or 3 hp motors. Looking at the same fan table says a 14" impeller can move a whopping 1377 CFM airflow at 8" but to do so it is drawing a real 3.77 hp. Neither a 2 nor a 3 hp motor will stand that kind of load for long. If as before we look at the minimum load from collecting from a big tool right next to the cyclone with minimal or no ducting this same sized impeller draws an even bigger 1649 CFM at 4.58 hp. That load will soon burn up either a 2 or 3 hp motor, but until it happens oh do these look good. So then the next question is how to they make them work with 2 and 3 hp motors and not burn out the motors all the time. The answer is the same. These blowers are far less efficient than commercial blowers so the design problems, poor manufacturing, and use with restrictive ducting saves lots of motors. It also makes for some pretty dismally poor test results. We do not get more airflow for nothing.
What makes your cyclone design a better choice than the many other offerings? Four things cost, airflow, separation efficiency, and overall resistance. You can build one from my plans and pay me little to nothing, or buy one from Clear Vue Cyclones with a 5 hp top quality motor for less than most other vendors charge for their 3 hp units with lesser quality import motors. Most small shop cyclones are built to provide the typical "chip collection" airflows of about 350 CFM. The bigger 5 hp cyclones provide a real airflow of about 800 CFM needed at our larger tools to provide fine dust collection ample to meet OSHA air quality standards. My cyclone design is engineered to provide over the 1000 CFM required at our larger tools to provide the airflow needed to meet the medical recommended air quality standards that are 50 times more strict than OSHA and already the EPA and European standard. The cyclone separation has a real separation efficiency instead of some fabricated efficiency made up in the back advertising rooms. All other cyclones put most of the fine dust and more into the filters. At this dust loading filters need cleaned every couple of hours and need replaced every three months. Those with my cyclone find they only need to clean filters once every few months and unless the ruin their filters the filters last for years. Many make two to three hundred pounds of fine MDF dust a day using my cyclone yet can go six months or more before they need to clean their filters. My prior "best" cyclone is the design that just about every other small shop vendor now sells. It only takes about twenty minutes of routing MDF before we must stop and clean the filters. Finally, my cyclone design has far less resistance than most other units so the horsepower of your blower motor goes into moving air and separation efficiency instead of getting wasted overcoming cyclone overhead. The combination lets you provide good fine dust collection airflow and separation before filtering that are far beyond OSHA, ACGIH, and approaching medically recommended standards today instead of struggling with equipment that mostly will not meet the OSHA standards that most have already abandoned because these air quality levels leave too many getting ill.
What do you have to say about the current top magazine rated cyclones and best selling cyclones? Do you recommend any of these? I suspect you want me to comment on the cyclone vendor who landed me in the hospital, but I am tired of their threats and law suits. They butchered the original New York State scalable cyclone design to the point it had all kinds of problems. I worked through those problems and freely shared my solutions. Today just about every small shop vendor now sells cyclones that incorporate the changes I shared to that original problem cyclone on my Cyclone Modification pages. So what you are really asking me to do is comment on how well my earlier cyclone functions. The simple answer is it works very well if powered by a 5 hp blower and vented directly outside. When used with fine filters, this cyclone posed so much of a problem I went back to the drawing board and came up with my current design. My current design is the only cyclone tested by many independent engineers, medical experts and scientists that they recommend as appropriate to vent inside into fine enough filters to protect our health.
In spite of the magazine hype which goes to those vendors who spend the most money, Delta has long made the most popular and largest selling small shop cyclones. I think they make a great cyclone if you put a big enough blower on it and direct the air outside exactly as the cyclone was designed. I am not at all in favor of any of the copies with tiny motors, blowers, and filters. They lack the airflow, separation needed to protect the filters, and ample filter fineness and sizing to make good fine dust collectors.
In terms of magazine ratings I have spent countless hours helping to educate magazine authors and editors to improve their testing protocol for cyclones and dust collectors. Future tests should look at the important things like separation efficiency, resistance, airflow at typical shop resistance levels, and filtering. Hopefully these many long discussions have weaned vendors away from this fallacy that "best" is the one that moves the most airflow claiming the highest CFM. As long as I don't have to stay under the motor's rated horsepower and maximum amperage I can change test pipes and blower openings to make just about any cyclone I want appear to be a "maximum airflow" winner. Far more important is will each unit provide the airflow needed for "chip collection" or good fine dust collection with the size ducting at the resistance levels typical for each sized shop. Best is the unit that best protects our health with enough airflow to collect the fine dust as it is made, enough power and air pressure to overcome the resistance of our normal ducting, and then the ability to safely get rid of that dust.
When I go looking for a vendor I want one I can trust. I don't trust any of the top rated cyclone makers because there has been too many years of funny business with bogus health claims, exaggerated airflows, falsified separation efficiencies, and dangerous filtering claims. I do know a few of the better known vendors continue to be in a very open and ugly public fight on their web pages and Internet woodworking forums leaving me feeling their bottom line is different than my interest in helping to protect the health of woodworkers. I have had so many pieces of hate email against all of these small shop cyclone makers except Jet and Delta that I hope to never receive another. These concerns sadden me but are not much of a surprise. In spite of my prior negative experiences I still chose to do my best to help all improve their cyclones. Many have lifted my advice then claimed it as their own. One now has three patents based on my work for which they gave me zero credit or compensation. Frankly, I have no need, want or desire to comment further. The only public recommendation I will make is their 3 hp cyclones work well for smaller one-car garage sized shops and their 5 hp cyclones work pretty well for average two-car garage sized shops. In both cases you should toss the filters and exhaust the air directly outside. I would not consider any of them appropriate to use with indoor filters.