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Dust Collector Cartridge Conversion

Created: August 9, 2002
Updated: February 17, 2021

1. Challenge

   Hey! I already am in enough trouble with the family for spending so much on woodworking tools. Can I convert my existing dust collector to something safer without breaking the bank? Humm... Don't want much do you? Putting on my shop apron…
   
   Just adding a cartridge filter, a separator or even a cyclone separator is not enough. Fine dust collection has been practiced since at least the 1950s and is well understood. Government regulations long ago recognized that "chip collection" that collects the same dust we would otherwise sweep up with a broom does not protect workers amply. The medical studies show those who work in shops with good "chip collection" still have such high long-term exposure to fine wood dust that almost all eventually become ill, some seriously. We now have government air quality standards to protect large commercial facility workers. Larger commercial facilities now use bigger blowers and better hoods that capture the fine dust as it is made and then they blow the airborne dust away outside. Even with these good protections, still many commercial workers develop medical problems from too much fine dust exposure. Small shop woodworkers must fend for ourselves because we have no standards, no vendor oversight and most of the dust collection equipment sold works so poorly it only creates a bad false sense of security.
   
   Unfortunately, many do not understand why we need to protect ourselves from fine wood dust. Too many small shop workers believe that because of our limited shop and woodworking time that we receive little exposure compared to professional woodworkers, but this is very wrong! Woodworking creates huge amounts of fine dust compared to how little it takes to harm our health. Most dust collection systems miss collecting much if not all of the unhealthiest fine invisible dust. Fine wood dust lingers until it gets wet, so in shops that do not vent their dust collection systems outside, the fine dust builds. Cal-OSHA small shop air quality testing shows almost all small shops that vent their dust collection systems inside build up such high amounts of this fine invisible dust that most small shop woodworkers receive more fine dust exposure in a few hours than large facility woodworkers receive in months of full-time work. The medical research is clear that the higher the exposure, the greater the damage to our health. We must start with the basics as even the best filter will help little if you do not take care of some other important things.
   
   After reading the basics you should realize that moving your dust collector outside or upgrading your dust collector filter will not solve your fine dust problems. I still support adding a fine cartridge filter to existing dust collection systems. Regular dust collectors put 100% of the fine dust into your shop air and a fine filter can greatly help that. The amount of fine dust you will collect as it gets made depends upon your hoods, tools, ducting and the size of your blower. To be safe you still need a mask on while you work and you need to regularly clean out your shop. You will have even better protection and less fine dust problems if you work with a strong fan blowing outside air through your shop while you work. To clean out our shops we must wear our masks, open all the doors and windows, then thoroughly blow out our shops. I use a big electric leaf blower or my air compressor.

2. Basics

   Because even the best dust collection systems miss collecting far too much fine dust, fine dust lingers forever unless it gets wet and unlike most large facilities, most small shops vent their dust collection indoors, so fine dust levels build to dangerously high levels. The fine dust is invisible without magnification, so even very clean looking shops build dangerously high dust levels creating a bad false sense of security. OSHA testing shows most small shops build such high levels of fine dust that as we walk around, turn on our tools, turn on our dust collection equipment or use our air compressors we launch enough fugitive fine dust airborne to fail our air quality tests. Fugitive dust is dust that previously escaped collection. Worse, because fine dust travels in any shared air, plus gets carried on our hair, skin, clothes and even pets it easily contaminates our vehicles, offices, and homes to affect all close to us including our pets. The only effective ways to control fine dust is to collect it as it gets made and then blow it away outside or provide good fine dust filtering.

   1. Definitions

      By definition airborne dust consists of particles sized under 30-microns, airborne dust when blown outside will disperse with no visible trace, and airborne dust rapidly breaks down when it gets wet. For reference a typical human hair is about 70-microns thick and there are one million microns in a meter. Fine dust is defined as airborne dust particles sized under 10-microns. Particles sized under 10-microns are invisible without magnification. OSHA testing shows woodworking makes roughly equal weights of different sized particles meaning one third of the weight of the under 30-micron airborne dust consists of fine under 10-micron sized particles.

   2. Hazards

      Traditionally fine wood dusts were only considered nuisance dusts, but more recent research shows all airborne dusts are unhealthy and fine airborne dust is very unhealthy. Medical research shows that fine dust particles sized under 10-microns slip past our normal protections then lodge deep in our respiratory systems where the sharp particle edges and points damage cells. That damage leads to infections and scaring. As this scaring builds it causes more serious problems including a significant loss of respiratory capacity, asthma and emphysema plus worsens other age-related diseases. This harm to our health is so bad that the EPA will close down office and public buildings if the airborne fine dust level exceeds 0.1 milligrams per cubic meter irrespective of the kinds of dust.
      
      Fine wood dust particles are worse because they carry very unhealthy and irritating toxic chemicals deep into our respiratory systems. The chemicals found in and on wood dusts can be deadly, cause cancer, cause nerve damage, cause rashes, cause allergic reactions from mild to potentially deadly, cause polyps, and can cause irritation ranging from redness and itching to boils and blisters. If you do not think fine dust are worth worrying about, you might start with my Medical Risks information. Or, you can read over the millions of references that come up when you do a Google search on "PM health risks" (PM means particle material another name for fine dust). Meanwhile, never work with any wood without first consulting a good Wood Toxicity Table and taking appropriate precautions!

   3. Volumes

      Woodworking makes huge amounts of fine dust compared to how little it takes to make unhealthy air quality and fail an EPA air quality test. A typical two-car garage sized shop contains less than 100 cubic meters of air, so only launching just 10-milligrams of fine wood dust airborne will cause a typical sized shop to fail an EPA air quality test. We launch more than 10-milligrams of fine dust from slapping a dusty shop apron or hand sawing just over seven inches of typical 3/4-inch-thick wood. OSHA testing shows very twenty pounds of sawdust makes on average 5 1/3 ounces of fine dust which equals 151,197 milligrams or enough fine dust to cause 15,119 typical two-car garage sized shops to fail an EPA air quality test.

   4. Behavior

      Fine airborne dust stays airborne in normal room air currents. It takes many minutes of still air to settle fine dust. Fine wood dusts rapidly spread like an odor to fill all shared air. Fine wood dust can be carried on our hair, skin, clothing and pets to contaminate all areas visited. Fine wood dusts are so light that fine dust rarely shows as a buildup on our tool and work surfaces. Fine wood dusts are so light that they do not ruin our finishes. Fine wood dust lingers nearly forever unless it gets wet, so the fugitive fine invisible unhealthiest dust that escapes collection builds in shops that vent inside. As a result, most of us end up with a bad false sense of security. Most have very clean looking shops that have dangerously high fine dust levels. After testing hundreds of shops only three who vented their dust collection systems inside did not have such serious fine dust buildup, that just walking around without doing any more woodworking stirred enough fine dust airborne to fail an EPA air quality test. Because this fine dust is invisible, the only ways to know if you have a serious fine dust problem is for someone to get ill, have allergic reactions or if we use a particle counter.

   5. Standards

      There have been many different airborne dust standards set by OSHA and ACGIH. Each different locality has been allowed to set their own standard, so we had a mixed-up mess. Many went with the early OSHA standard which only requires good chip collection. Eventually the current airborne dust standard emerged as set by the Environmental Protection Agency (EPA). The EPA standard that says anything larger than 0.1 milligrams of fine airborne dust per cubic meter of air in our shops will fail an EPA air quality test. The E.U. and U.K. all use similar standards.

3. Blindsided

   Even more get multiply blindsided by dust collection vendors. The vendors are in such fierce competition that many falsify their specifications and almost all cite maximums instead of working values. Most small shop users tend to believe that these maximum values are working numbers when the reality is most are nearly double what these systems provide in real use.

   1. Falsified Airflow

      Many think that if they have a dust collector or cyclone rated at more than 1000 CFM, then they have a big enough system, but that is wrong. Dust collection systems depend on blowers to move air. If you run your blower with no ducting, filters, dust collector or cyclone and use a special bell-shaped inlet that causes the air to feed into the blower with less resistance your blower will move a maximum amount of air. Most small shop vendors falsely advertise this maximum possible airflow as the working airflow. A blower moves different amounts of air depending on how much resistance it must overcome. Things like our ducting, duct elbows, tool ports, and dirty filters all add resistance. The overall resistance in a dust collection system is called static pressure. If you have a high static pressure due to a dirty filter, long ducting runs, and a small tool port your blower will barely move air because of all that resistance. In normal use most dust collectors, cyclone systems, shop vacuums and even air cleaners move about half of their maximum possible airflow which is too little to provide good fine dust collection.

   2. Falsified Filtering Claims

      Many also believe they have a shop vacuum, air cleaner, dust collector, or cyclone that comes with a filter that protects their health. The advertisements and even specifications show very high filtering performance, but again this is a maximum instead of a working filtering level. I ran a large dust collector and cyclone test for a magazine and was able to test almost every major small shop dust collector and cyclone including their filters. The filter results were so bad the editors cut that testing out of my article. That testing showed the vendors falsified their filter claims badly. Almost all small shop dust collectors and cyclones came with 10 to 20-micron filters that were advertised as anything from 0.3-microns to 2-microns.
      
      Competition is fierce and filter material is expensive, plus the finer the filters the larger they must be rapidly increasing costs. Vendors can simply make up whatever filter numbers they want to use because our truth in advertising laws let them claim any filtering level they want if they can prove their product meets their claims. Since they do not share the airflow at the desired rating, they can simply plug their filter until they get the desired filtering level. Even a large open screen can be claimed to be a 0.5-micron filter if we pile on enough rock and dirt if nobody cares if the result will not pass air. Too many vendors simply keep changing their filtering level on filters that in real use pump the most harmful invisible fine dust right through.
      
      Filter makers provide two different ratings for every filter they sell, an indoor rating and an airflow or outdoor rating. The indoor industry filter rating standard is set by ASHRAE and requires that all filters be tested when clean and new. As a filter ages material builds in the filter pores that does not come out with normal cleaning. This material blocks airflow, but increases filtering. Over time the filter builds up as much material as can be carried through a normal cleaning creating what is known as a fully seasoned filter. Fully seasoned filters pass significantly less air so vendors use this airflow to compute how large their filters must be to provide good airflow. Vendors also share the filtering level of a fully seasoned filter which often filters as much as twenty times better than brand new. During seasoning which can take up to a year for light hobbyist use these filters freely pass the unhealthiest invisible dust. Worse, even when fully seasoned the fine dust will migrate through adding to the fugitive dust in our shops. Most will flood our shops with fine dust any time we turn on our dust collection systems.
      
      To many small shop vendors make totally false filtering claims forcing the more reputable to use the fully seasoned ratings to appear competitive. To get good fine filters you almost always must go directly to a filter supplier. There are a few good filter bag makers but you need to specify at least MERV-15 filter material. Unfortunately, to get enough surface area that good filter material does not quickly clog, we need huge bags that are far too large for most small shops. It is far better to get a good cartridge filter. The bad news is almost all small shop fine bag filter and cartridge filter equipped dust collectors and cyclones simply allow most of the finest unhealthiest invisible dust to pass right through.

4. Controls

   Good fine dust collection requires you use the needed controls or your shop will stay filled with very unhealthy levels of fine dust exposing you and those close to you. The major firms who guarantee customer air quality freely share what they have learned through decades of experience. They learned to capture the fine dust at the source most need larger blowers, better tool dust hoods, bigger tool dust ports, sometimes better tool designs, larger diameter ducting and better filters. They found:

   1. Source Capture

      Normal room air currents will blow fine dust all over unless we capture the fine dust at the source.

   2. Venting and Air Cleaners

      Trying to get rid of the fine dust by venting outside or using an air cleaner just does not work because venting and filtering are far too slow to bring the air quality down fast enough to avoid failing an air quality test.

   3. Masks

      Far too many wrongly believe any kinds of mask or PAPR (powered air purifying respirator) provides good protection, but most masks and small shop PAPR systems leak and have too open filters. The minimum requirement for a good mask is a tight-fitting silicon seal and dual fine cartridge filters rated as either MERV-16 or as HEPA quality. A good mask only protects you while you wear it. Few put on their masks early enough or leave their masks on long enough. Using an air cleaner or even a modest sized exhaust fan takes hours to clean your shop air amply to take off your mask. If you start with a clean shop and keep a good strong fan blowing air through your shop, this will keep your air clear enough that our particle counters show most can remove masks and turn off fans after about a half hour of no woodworking. See my Doc's Orders for specific recommendations for your mask, fan, etc.

   4. Airflow

      Just about any small shop dust collector with a real airflow of 350 CFM will do a good job of chip collection. It does not seem reasonable that a system able to lift a bowling ball cannot collect the fine dust that we can move with the lightest breath. We already know why. A shop vacuum on blow will blow stuff all over our shops, but on suck the same vacuum will not work until you get the nozzle right next to what you want to collect. This is because sucked air speed falls off at four times the distance squared times Pi, or more than twelve times the distance squared. This is why moving our vacuum nozzle just a bit away kills collection. In engineering classes, we show students this by trying to move a balloon with a straw without touching the balloon. Blowing moves the balloon easily, but it is near impossible to get the straw close enough to move the balloon by sucking without touching. Our dust collection equipment works off sucked air. That leaves only two options for good fine dust collection without normal room air currents blowing the fine dust all over.

      1. We can totally enclose the dusty activity then just about any kind of collection system can remove the fine dust.

      2. Or we must use really good hoods and move lots of air. Testing shows that to pull in the fine dust before it gets blown all over show we must surround the working areas of our tools with at least 50 feet per minute (FPM) airspeed out to a distance of just over 17 inches all around the working portions of our tools. Further testing, the air formulas and decades of experience show to get that air speed and distance to get good fine dust collection we need at least 1,000 CFM airflow at most small shop stationary tools.

   5. Hoods

      Hoods are very simple. Air at dust collection pressures moves at about 45 miles per hour, but our blades, bits, cutters and even sanders can launch dust at over 100 miles an hour. If our tool hoods do not amply contain, direct, and collect these fast-moving air streams then there is zero chance of getting good fine dust collection ample to avoid failing air quality tests.

   6. Required Airflow

      Real working airflow tends to be about half of the maximum airflow. When using minimal resistance filters and little to no ducting and no separator, even the best 1.5 hp dust collectors move just over half the airflow needed to meet the 1000 CFM needed for most small shop stationary tools. The blower performance tables show we need at least a 3 hp dust collector or 5 hp cyclone based system to move the 1000 CFM needed for good fine dust collection.

   7. Size Matters

      At dust collection pressures air is like water and will barely compress at all, so any undersized ducting, hoses, fittings, or tool ports will kill our airflow that we need for good fine dust collection. We know we can control the volume of a garden hose by opening or closing a valve. If you changed your garden hose to 1/8th inch tubing, you would not be very happy with the result because that tiny pipe would all but kill the water flow. In fact, when we measure the airflow when using different sized ducts, we learn dust collection pressures only support moving about 22 CFM through the 1" diameter and 87 CFM on the 2" diameter duct and hoses found on most handheld power tools. We have to use a much stronger suction such as from a vacuum to collect from these sized ports. A 3" diameter duct only supports moving 186 CFM. The low pressure of our dust collection systems is why most recommend never using smaller than a 3" diameter port or hose when working with dust collectors or cyclones. A 4" diameter port or hose only supports moving 349 CFM which does a great job of chip collection meaning collecting most visible sawdust and chips. A 5" diameter duct or port only supports 545 CFM and 6" diameter duct and ports only support 785 CFM. It takes a full 7" diameter duct and ports to support 1069 CFM which is the minimum size to support our needed 1000 CFM required for good fine dust collection. A very few vendors such as Clear Vue Cyclones use oversized blower impellers to increase the pressure enough to permit moving over 1000 CFM through 6" diameter duct. Almost all other small shop dust collector and cyclone makers only support moving the needed 1000 CFM through 7" diameter duct. Also, our shop vacuums move too little air to collect the fine dust unless we totally enclose the dust making activity.

   8. Ports

      Most tools come with the 4" diameter dust ports needed for good chip collection that collects the same dust and chips we would otherwise sweep up with a broom. These 4" sized ports restrict the duct opening to 4" which only supports about 349 CFM which is far from the needed 1000 CFM needed at most small shop stationary tools. To get ample airflow most will need to have 7" diameter down drops that split into enough ports that are just over the roughly 0.26 square foot area of a 7" duct. Picking duct with the smoothest interior helps some, but not enough to overcome the size problems. You can add different sized ports to equal that 0.26 square foot requirement. A 3" duct has an area of 0.049 square feet, 4" at 0.087 square feet, 5" at 0.14 square feet, 6" at 0.2 square feet, and 7" at 0.26 square feet. With the extra powerful blowers, you can use a 6" down drop and either a 4" and 5" or two 4" ports. For instance, on my table saw I use a 5" port on the cabinet and a 4" port on the over blade guard hood.

   9. Tools

      Many tools will not behave as they come from the factory because they have internal ducting and openings that are just too small. If you cannot change the internal ports, duct and openings, then you are not going to get good fine dust collection on that tool unless you only use it in its own totally enclosed space such as is required for many of our CNC routers.

   10. Ducting

       Almost all available inexpensive small shop dust collection ducting and fittings are too small and the 7" diameter duct that most of us need is not readily available or too expensive. Worse, most end up going with inexpensive options that significantly reduce airflow. Most like to use flex hose, but its internal ribs make it flow significantly less air. Likewise, use of spiral duct adds more resistance than laser welded steel or PVC duct. With the pressures available from small shop blowers, we need 7" diameter duct to move the 1,000 CFM that the air engineers have proven is the minimum to get good fine dust collection at our larger tools.
       
       The classic graduated sized ducting designs that look impressive and work well for chip collection do not work for small shop fine dust collection. Traditional dust collection system designs skip the blast gates and keep increasing the size of the main and blower to handle all the downstream airflows. This is not the case with small shop systems that normally only have one duct open at a time. In small shops we only have one tool working at a time, so we need a fixed ducting main size and down drops all of the same size with blast gates to only collect from one tool working at a time. We also have to worry about our ducting size being too large or small. We know that as we reduce ducting size airflow meaning CFM drops quickly. Likewise, as we increase the size of our ducts, airspeed meaning FPM also drops quickly according to the formula FPM = CFM / Area where Area is measured in square feet. As with commercial systems we must size our down drops and mains ample to provide enough airflow and keep the airspeed moving fast enough to keep our vertical runs from plugging and horizontal runs from building up dust piles. It takes a minimum of 3,800 FPM to keep our vertical runs from plugging so most air engineers design for at least 4,000 FPM for all vertical runs. Likewise, it takes a minimum of 2,800 FPM to keep our horizontal runs from building up piles in the ducting so most air engineers design for at least 3,000 FPM for all horizontal runs. Any spark from say cutting a nail or staple ends up with a potentially serious problem because the high airflow acts like a bellows fanning that spark into a potentially major problem. When you open a larger gate downstream then all the piles go slamming down the line. These piles slam down our ducting so hard they can blow apart ducting joints, ruin our dust collector blowers, break our impellers, and blow right through ruining our expensive filters.

   11. Filters

       The National Institute of Health (NIH), OSHA, EPA and similar organizations in countries throughout the world agree that the fine wood dust particles that go right through most small shop dust collector filters, including fine filters, are very unhealthy and dangerous. There are many types of fine pleated filters used in dust collection. Most polyester filters will work, but they are much more expensive, hard to clean, have very limited surface area, and tend to load up and fail. I worked with Wynn Environmental to build custom filters that let us flow the air from inside to out.

5. Warnings

   1. Traditional bag type small shop dust collectors are more dangerous than if we went back to brooms and dustpans because these units are dust pumps that recycle the most hazardous particles and keep them airborne.

   2. Bag filters are a poor solution compared to good cartridge filters. The smaller the filter size the quicker it will clog and lose its ability to pass air. When airflow drops, we lose the air volumes needed for good fine dust collection. Almost all small shop filter bags are far too small so will clog almost immediately when used with a dust collector or cyclone because too much dust goes into the filter. Also, cleaning wears out our filters making them more porous so they pass more and larger dust particles. Rather than figure out a way to avoid so much going into our filters, most small shop filters are wide open meaning 10 to 30-micron filters that freely pass most of the fine invisible dust. Not wanting to constantly clean and replace my expensive fine cartridge filters is what inspired me to build my much better separating cyclone.

   3. The fancy paddles, flappers, and other cleaning systems offered on cartridge filtered dust collectors are there because these units also have a basic design flaw. Almost all dust collectors allow everything to blow right up into the filters. This means that the cartridge filters quickly plug and need constant cleaning. That tradeoff appeared acceptable to me at first until I continued testing and found the cleaning quickly wore out the filters and the high velocity chips poked holes in the cartridge filters. With thousands of new larger holes after every use and cleaning making the holes even worse, soon my expensive fine cartridge filters freely passed larger particles. You can tell when you have a problem when your shop again has a coating of fine dust everywhere. If you have a pressure meter a filter will continue to increase the pressure until it is fully seasoned. It can take months to years to fully season. The with use the filter gets torn open from the razor-sharp edges and points in wood dust. The more a filter wears the lower your pressure gauge will show. Fine cartridge filters work best if protected by a cyclone separator. Other options like a baffle (see Phil Thien's baffle design) or a fine screen will help block the larger filter hits, but they need to separate down to 0.5-microns before they get my blessing. Trying to protect a cartridge filter with a traditional trashcan separator does not work. Almost all of the available trashcan separators use 4" duct and ports which kill our airflow down to about 349 CFM. This may reduce filter hits, but kills the airflow needed for good fine dust collection. We must use bigger duct if we want to capture the fine dust. The air formulas and simple testing show most small shop dust collectors need to be at least 3 hp and use 7” diameter duct to move the 1000 CFM for good fine dust collection at most stationary small shop woodworking tools. A 6" duct will only move a maximum of 785 CFM, but even with this sized duct, the airspeed will be so high it will scour traditional trashcan separators clean of all but large blocks. It takes a trashcan separator that is about 5'2" in diameter and 7' tall to handle 875 CFM.

   4. In the late nineties John Dillbeck spotted the idea of using an extended inlet to reduce internal cyclone turbulence and improve fine dust separation in an obscure cyclone article. He shared that information on the Badger Pond Internet woodworking forum and Jim Halbert figured out a simple way to make neutral vanes. Someone coined the misnomer "neutral vane" and Jim’s extended inlet has been called this ever since. I worked with Jim to adapt and optimize his design for cyclone separators. Shape and size make a huge difference in how well neutral vanes work. I shared my research and designs on these pages. Now most small shop and even some large commercial vendors provide a neutral vane and many other of my suggested cyclone enhancements. Now almost all small shop vendors use the neutral vane modification to improve airflow and separation efficiency. Getting rid of much of the internal turbulence also uses less power. Although adding a neutral vane improves airflow it does little to help with fine dust separation.

   5. A huge problem with putting a cartridge filter on a dust collector is finding a workable filter that lets the air flow through backward. Almost all commercial cartridge filters flow the air from the outside to the inside of a cartridge filter. This is not a big deal if you use the expensive all polyester spun bond filters that can flow the air either way. Cost and availability force most to use cellulose (paper) blended filters. These filters are treated so things that collect on the outside slip off. If you flow the air through the wrong way particles get trapped between the paper and outer layer and the particles do not come out with cleaning. Filters with the air going through the wrong way quickly load up so much they soon block almost all air flow. You need the right kind of filter that is built different than traditional commercial dust collection filters. These filters were so hard to find that I worked with a filter company, Wynn Environmental to build these special filters and strongly recommend them as a source for your cartridge filter upgrades.

   6. Most who monitor their filters replace them when after cleaning their pressure falls below the clean new pressure or when the pressure falls one water column inch below the maximum seasoned pressure. Even fully seasoned filters continue to pass fine dust, they just replace it as fast as the finer particles work their way through. This means almost all filters rated less than the Merv-15 minimum we need are dust stores which can badly contaminate your shop before you do any woodworking.

   7. Adding almost any small shop cyclone except my design does not improve filter loading much. Most small shop cyclone designs are downscaled versions of larger commercial cyclones we see outside most woodworking facilities. These cyclones use very high internal turbulence to knock the fine dust from the heavier dust and chips, then they just blow the airborne dust away outside. Blowing this same airborne dust into our cartridge filters is what quickly clogs and soon ruins fine filters.
      
      Too many small shop cyclone vendors now cheat on their testing. Many simply sell very open filters that freely pass the dust their systems cannot separate. Most vendors also test their cyclone efficiency using previously collected dust that already has the airborne dust blown away. Odds are if you test with the dust you already successfully tested, you will get a 99% efficiency. One vendor actually claims their design is so efficient that most only need to clean the filters a couple of times a year. My particle testing showed that vendor's filter was so open it freely passed 30-micron and smaller particles. When tested with real dust that still contains the airborne dust most small shop dust collectors and cyclones get roughly 0% (zero) fine dust and 0% (zero) airborne dust separation efficiency. These cyclones and dust collectors blow all the airborne dust right through so they work well for exhausting outside, but using them with fine cartridge filters is foolish. If you cannot blow the air outside, you really need a much better cyclone separator to protect the filters, minimize cleaning, and maximize filter life.
      
      Wanting more separation efficiency, I went back to the swirl tube and cyclone physics, came up with a better cyclone design that was far more efficient. Today almost all small shop dust collectors and cyclones still send most of their airborne dust into their filters. Independent medical school testing shows my improved cyclone design provides 99.9% efficiency separating off particles sized 4.7-microns and larger. My design uses less energy as it has a smoother internal airflow meaning uses less horsepower. Having your filters only having to deal with less than one sixth the dust means instead of having to clean your dust collector or cyclone filters every few hours, most can go months between filter cleaning. More importantly, with only tiny particles reaching your filters, most of these do not have the mass to cause their sharp edges to tear up your filters. Instead of having to replace filters every three months like full time commercial shops, most using my cyclone design have filters that last many years. Clear Vue Cyclones makes and markets my cyclone design.

   8. Upgrading to a cyclone can be expensive, so many want to add a cartridge filter to their existing dust collector to keep from recycling the unhealthiest fine dust. Although you can significantly reduce the fine dust in your shop air with a cartridge filter upgrade, you are not going to collect that fine dust at the source unless you have a big enough dust collector and upgraded hoods.

   9. The more air a blower impeller pushes, the harder the blower motor works. Trying to move too much air can easily over stress your blower motor. The increased airflow from adding a cartridge filter and larger ducting can potentially burn up a dust collector motor from working too hard trying to move too much air. Cartridge filters have so much surface area that the resistance can fall too low. This can double total airflow until the filter seasons. Likewise, moving from smaller to larger ducting can also move so much air we can easily burn up our dust collectors when shifting from 4" to the 6" or 7" diameter ducting needed to move enough air at our larger machines for good fine dust collection. I recommend you use an amp meter before and after adding a cartridge to ensure the motor does not draw too much current and burn up. Adding a partially closed blast gate before the blower inlet can cure this problem.

   10. To upgrade a dust collector with a cartridge filter we need a good separation ring and good inlet design. These components limit how much dust blows up into our cartridge filters. Remember, not only do the chips punch holes, the chips and sawdust get stuck in the pleats creating a cleaning nightmare.

6. Fix Your Tools

   Economics have turned most small shop woodworking tools into copies of older professional woodworking tools that are now made in third world countries. Most of these older tools either had no dust collection or at best limited chip collection. To successfully collect fine dust from these tools they mostly require some modifications to control fine dust as it is made and permit moving enough air to capture that dust. You must also do your homework followed by making needed changes to your tools.

   1. We also mostly only have 4" dust collection connections known as ports on our tools. Convincing ourselves to voluntary cut larger ports in our expensive tools to replace the too small tool small dust ports with the bigger ports we need is not fun or easy to do.

   2. Likewise, we must also replace or change our tool hoods to control and allow capturing the fine dust at the source, or we are wasting our time and money.

7. Best Solution

   At one time I recommended doing your own conversion, but Wynn Environmental now provides a much better solution. The best approach I have found is to use either a separator or Thien baffle to keep the larger chips from plugging the filter and punching holes in it and then install a single stage dust collector conversion kit! Wynn offers the only solutions that are affordable, of ample size and allow flowing the air through your filter in the correct direction. You will need the Wynn Environmental dust collector conversion filter and mounting kit.