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Dust Collection

Dust Collection Resource Page

If you want to start or improve your dust collection system, you’re in the right place.
Dust Collector Filter Bags

Even though it looks like a hot air balloon, the extra surface area has gained me a nice 21% increase in CFM at my planer.

I’ve been asked more questions about:

  • Dust Collection Design & Layout
  • Dust Collectors
  • Ductwork
  • Air Cleaners
  • Fittings
  • Sizing Systems and Ductwork
  • Tool Hoods
  • Filtration
  • Filter Bags
  • Accessories

than anything else.  So these things will be the primary topics here on this page.

You can read all the articles I currently have on these topics using the links below, plus you can find products and resources for everything linked here as well.  Some of the stuff you can buy through the links here give me credit (at no additional cost to you), so using these links is appreciated and thanks in advance!

If there’s anything you’d like to hear more about I’d be happy to noodle over it and post an article on it.

If you want to know something that’s not on here, just want some clarification, or whatever you want, leave a comment below or in any of the articles (I’m notified when that happens so I can reply).  Or if you’d rather, feel free to shoot an email to:

I will be adding things here that I use and explain how they’re used and why it’s good stuff.

Thanks again, and here’s to Optimizing Your Woodshop!

Gotta get more clamps,






Alright, here we go.

Dust Collection Articles

Did You Know?

How to pick:  Cyclone vs. Single-Stage

Of course one of the first questions people have is do you need a cyclone?  Do I really need to spend over $1000?  Well, you don’t really need a cyclone as long as you understand a few things.

The purpose of a cyclone is to separate the larger chips and dust from the airstream before it hits the impeller and filter media.  That’s it.  Also, it happens that most cyclone dust collectors are made with higher horsepower motors as well.  This is to help compensate for the fact that the cyclone portion causes an extra pressure loss in the overall system.

Single-stage dust collectors draw in the chips, dust and errythang directly into the impeller and then into the dust bin and filter.Dust Collection - Filter Bag - Singed Felt

I’ve seen sooooo many woodworking magazine articles saying that “Oh my gosh, don’t let any wood chips hit your impellers or everything will explode!“.  Well I have a Jet DC-1100 single-stage dust collector for years and I’ve heard all kinds of things hit that impeller and there’s no damage to it except some chipped paint.  It’s metal, after all.  Now you don’t want screws or nails hitting the impeller due to the spark danger, but really I haven’t had any issues with stray dovetails breaking off and getting drawn in, knot fragments, etc.

The other thing people say about single-stage machines is that chips and excessive amounts of dust will hit the filters.  True, this will happen unless you have either a deflector cone like the Jet Vortex, or a “Thien Baffle” type device, or perhaps a “separator” lid on a trash can or bucket.  You can read more about the baffle concept from Jens Larsen here, or see some photos and discussion on the Woodworking Talk forum.

If you have a cartridge type filter, high-velocity chips or excessive static pressure can damage the thin filter media, poking holes in it.  This would render the filter kinda useless for fine dust collection.

If you have a plain felt filter bag (or worse a woven cloth one…), excessive dust will plug up all the tiny openings and you’ll lose suction dramatically.  Losing suction will mean you’re not picking up the fine dust at the machine, again making your dust collection ineffective.  But, what all of these magazine articles don’t acknowledge is that if you have a singed felt filter bag, such as one from American Fabric Filter, it’ll hold the proper amount of dust cake, and the rest will either fall off naturally or with a light tap.  Do not excessively clean singed-felt filter bags; generally you’re supposed to leave them alone other than tapping them lightly to knock off excessive dust cake.

You can read more about how singed felt works here.  I retrofitted my Jet single-stage collector with an oversized 16 0z. singed-felt filter bag from AFF, and it filters fine dust down to 1-micron with little “seasoning” from a dust cake; for more details on this you can read this article, or this one.

Bottom line?  I like the concept of not having to deal with thin pleated filter media getting all plugged up, so I lean toward a singed felt filter bag like the large industrial baghouse collectors use, and getting 16 oz. heavyweight material is recommended (they offer 10 oz. or 12 oz., which have a higher permeabilty but are less effective at stopping fine dust than 16 oz.).  Just make sure you size it with enough surface area for the maximum CFM you need.

The manufacturer can usually tell you the permeability of the filter bag; this means how much CFM per sq. ft. can pass through at a particular static pressure (usually 0.5″).  The filter bags from AFF have an air permeability of 18-35 CFM per sq. ft. of singed felt media while clean.  Of course, with a dust cake, that will decrease.  AFF recommends upsizing even more so that when the dust cake develops the pressure drop is still minimal.   So I had them upsize it to give me 14 CFM per sq. ft at 800 CFM.  I could’ve had it even larger.  When I upgrade, I’m thinking of using a single-stage collector with two barrels/ filter bags and simply order the second one even larger to give 5-10 CFM per sq. ft.

Ask the manufacture for 3rd party certification as to the particle arrestance capability of the filter you’re buying; saying “1-micron” isn’t good enough because what if it stops only 10% of 1-micron particles?   I got the paperwork from AFF for a clean singed-felt filter bag.  They were awesome and of great help when I had questions.

Their chart was for 12 oz. felt but I got the beefier 16 oz. which performs even better.  Plus, as the singed felt develops a dust cake the particle arrestance will only increase.

I’ve been using my 16 oz. filter bags for months now, and haven’t noticed any loss in suction.   When I measure the CFM I’m getting similar numbers  to when I first installed it.  The only improvement I plan to make in the near-term is adding my own version of the Thien Baffle or Vortex Cone and see if there’s any loss in suction.  I’ll actually measure the airflow using an anemometer.

Size the dust collector for your particular ducting design’s static pressure losses to get the CFM you need at your hungriest machine.  This is why you want to ask the manufacturer for a fan curve.  It will tell you the CFM you’ll get at various static pressures.  Sometimes you can search online and find tests that others have done to get this info.

Down the road I may increase the horsepower of my motor so that I get more CFM at the static pressure of the longest duct run in the shop.  More CFM picks up the fine dust, as described below.  But you can certainly get a single-stage dust collector with a large motor.  I’d just upgrade the filter bags.  Or you can get a cyclone, but use singed-felt filter bags.  But understand that the cyclone stage causes a lot of static pressure losses, so sometimes the performance suffers even in a 3 hp collector.

If you do get a cyclone, make sure that the brand you buy has a cyclone design that is good at separating the dust out of the air before it hits those delicate cartridge filters.  And oversize the filters on purpose.  Oh, and don’t blast compressed air close to the media; be gentle or they’ll get ruined.

Woodchip Tip:  Get rid of that woven cloth lower bag.  The part of your dust collector that fills up with dust/ chips is not meant to “breathe”.  Use a sealed dust bin, drum, plastic bag, or a duck canvas bag.  I got the duck canvas bag from AFF because it’s really durable and I don’t want to keep buying bags.  Plus my cat, Crayon, likes to claw at things…  Use foam adhesive-backed weather stripping to seal the connection to the collector’s barrel.

Did You Know?

How to Capture Fine Dust at the Source

In order to keep dust out of our noses and off of our stuff we need to draw it in as close to the source of that dust as possible.  When blades and bits strike wood, the dust and shavings are flung away at high speed but then slow down in the air and eventually sink downwards.  Chips and shavings do this pretty quickly, while fine dust particles float around the shop for hours.  Now we’re breathing these in as long as we’re in the shop space.

Lungs have a tough time filtering out these small particles so they’re the most dangerous; and you can barely even see these.  If you’re capturing the fine dust, you’re also getting the bigger stuff too.

4 things to consider when aiming to capture dust are:
  • Tool Hood Shape/ Configuration
  • Tool Hood Size & Duct Connection Size
  • Airflow Rate (CFM)
  • Capture Velocity/ Distance from Source of Dust

Tool hood shape comes into play when you think about how you’re preventing the flying dust from continuing its path away from the blade or bit; in other words deflecting it so that your airflow can capture it.  “Enclosing” the dust region is the most effective way of stopping the dust from escaping, but you need to have openings to allow air to be drawn into the hood and ductwork to carry the particles away.

The hood size and the duct size influences the air velocity and air quantity (CFM) used to capture the dust.

Distance is important too; the further away the suction hood/ duct is from the source of the dust the less you’ll capture.  On the suction side of things, air velocity degrades rapidly with distance.  The formula for calculating this shows that to maintain a certain capture velocity, you have to increase the airflow by a lot; it’s CFM = Velocity x [10 x Source Distance (squared!)+ Area of Hood Opening],

or simply:


where V is velocity at the distance from the hood “X”, and A is the area of the hood, or if it’s a plain duct, the duct cross-sectional area.

Make sure all of the units are in feet.  This equation is accurate to a distance of around 1.5 x length of one side of a square hood or the diameter of a round duct.

Note that the distance from the source is squared, so it’s a big deal.  The CFM required to maintain a good suction velocity becomes ridiculously huge when you’re too far away.Dust Collection Fine Dust Anemometer

I tried this using my anemometer and as I moved the instrument away from the flex duct, the velocity dropped to almost nothing after 1 foot.  On my Jointer, I put it right at the flex duct, and measured 6,332 feet per minute.   Then I moved it 4-5″ away from the flex hose, and measured 539 feet per minute!  By the equation above, I’d want to be no further than 8″ away to effectively capture most of the dust in that area  I’d also want to install deflectors to keep the dust from escaping before being drawn in.

This concept works for downdraft hoods, too, and hoods placed sideways on a table.  Say you have a plain 4″ round duct near your dust-making blade.  To maintain an ideal velocity of 100 ft./min. to draw in the dust, you decide that the duct can be 8″ away.  This means you’d need about 450 CFM to accomplish this.  If you’re 12″ away, then you’d need 1,010 CFM.  If you’re only 6″ away, 260 CFM will do the job.

If there’s anything to note from this, it’s put the dust hose or hood within 6-12″ of the source of dust, and shroud the area to contain the dust.

Most of the time you’re barely getting 500 cfm, and with a 4″ or 6″ diameter duct, you’re looking at wanting to be 8″ away, with an 8″x12″ hood, you want to be 6″ away.  If you had a 5hp collector that gave you 900 cfm, you could be 12″ away and be ok.

I made an excel spreadsheet you can use to calculate it if you’re curious.  You can enter numbers right on this page; try it!

Here’s the Calculator:

Note:  Velocities in the above calculator are NOT duct velocities, it’s the airspeed at a certain distance from the collection/ suction source.


Say you have a dust hood on your sanding bench, and it’s 12″ away from where you’re breathing.  It’d be nice to induce a 100 feet/min. draft to that distance to draw fine dust away from you.

  1. Using the first calculator, find “12” in the first column.
  2. Then choose the diameter of the dust hose you’re using.
  3. Alternatively, you can go to the 3rd column and manually enter any hood area you want, as long as it’s in sq. ft.
  4. The red number in the 4th column will tell you what CFM you will need to induce a 100 ft./min. draft at a distance of 12″.

The second calculator lets you enter the CFM if you know what it is, and determine the velocity you’re getting at various distances.  You can enter your own number under the 3rd column “Hood or Duct Area” if you want, just make sure it’s in sq. ft.  You can also enter your own collection distance in the first column, too.  Ultimately, you’d like to see more than 5o ft./min.

Dust Collection Product Showcase

Dust Collector Keychain Remote 
  • Electrical Remote Dust Collector SwitchDust Collection RemoteRemote for 120V Dust Collectors
  • Remote for 240V Dust Collectors
  • Your dust collector plugs into the receiver, which plugs into your wall.  I use a dedicated circuit because I don’t want any other machine to be on the same breaker.
  • The keychain remote hangs on the wall near the shop entrance, and I clip it on my belt loop at the beginning of a shop session.
  • Save yourself from walking over to your dust collector every time you want to make a cut.  Your efforts to arrange your machines to idealize your workflow are meaningless if you have to do that.
  • Encourages use of your dust collector for every cut so you don’t accumulate dust all over, making for less cleaning time and more energy for you
  • Relatively inexpensive, I would buy it again for sure.
Duct Sealant
  • In order to get the airflow you need, sealing the sheet metal duct seams is necessary.  I brush this on elbows, fitting joints, and longitudinal seams on straight duct.Duct Sealant - Dust Collector
  • Don’t worry, if you need to disassemble something this sealant won’t permanently glue your ductwork, and it’s water-based.  Just unscrew the self-tapping screws and pull apart.  When you put things back together and re-brush on the sealant.
  • I use foil tape at some junctions as well.  Some joints are under stress or get moved around so the sealant can sometimes separate.  You’ll see where those are over time; I just re-seal, let dry, and apply foil tape to those areas.  Don’t turn on the fan until the sealant has cured for at least a day.
  • For very little money, you’ll increase the amount of fine dust your system collects from your tools.  You need lots of CFM in order to collect small particles from a reasonable distance from the suction point.
Foil Tape
  • Foil tape, specially designed for ductwork, is what you want to use to secure duct joings that get banged around.Foil Tape applied to dust collector duct cap
  • Please don’t use “duct tape”…it’s really not for ductwork, and it’ll make industry professionals sad.  The adhesive on “duct tape” doesn’t last that long, and doesn’t hold up well when the metal ducts get cold or hot.
  • There is “regular” foil tape, which is not listed for use on ductwork.  You’ll be disappointed with this, too.  Use one that is listed, i.e. UL-181, for the application you’re using it for.  You can tell it’s at least listed because it’ll have writing all over it, a signal to a code official during inspection.
  • This is another one of those low-dollar items with a nice payback; keeping our system sealed will increase the CFM we get at the tools.
Duct Crimper Tool
  • For sheet metal ductwork, we often need to cut straight ductwork to custom lengths with tin snips. That cut end may need to fit into another duct.  To do this, you use these duct crimpers to narrow
    Dust Collection Crimpers

    These crimpers allow you to fit the ducts together; just remember to point the crimped end toward the airflow.

    one end so that it slips into an adjacent duct.  Then all you do is put 3 self-drilling sheet metal screws to secure the joint, and seal it.

  • These are pretty inexpensive and allow you to work on your shop’s dust collection now and in the future, and you can use it to install sheet metal ductwork for your home’s exhaust fans and air conditioning unit.
  • You can use these to crimp all sorts of metal for decorative effect on projects, or just annoy people by putting wavy patterns in all of your magazines and phone book covers.
Hose Clamps (Bridging Type)
  • We need hose clamps to attach flex hose to blastgates and rigid ductwork.  These bridging type bands work much better than standard straight hose clamps because they “bridge” over the flex duct Dust Collection Flex Duct Hose Clamp Bridgingridges.
  • Also, typical hose clamps have a hex screw that you need a tool to tighten; these have a nice key that you can loosen and tighten by hand.  I’ve begun to replace all of mine with these.
  • Typical locations for these will be at your tool connection, and at the duct drop/ blastgate.  So when accounting for how many you’ll need, count up how many tools of each duct size and multiply by 2.
  • These apply more even pressure all around the flex duct for a better seal; traditional hose clamps leave gaps that you should seal over with foil tape or something.
  • You can get them for 4″ flex5″ flex, or virtually whatever you need.
Airflow Meter (Anemometer)
  • With an anemometer, you can measure the velocity of the airflow in your dust collection system, and by multiplying that by the cross-sectional area of the duct
    Dust Collection Filtration-Anemometer

    Using this anemometer I can measure the velocity in my dust extraction ductwork and by multiplying it by the area (in sq. ft.) I get the CFM.

    you’re measuring, you get the CFM.  So, say you want to target 600 cfm at a tool, and you measure 450 CFM.  That tells you that you need to relieve some of the static pressure losses in that duct run, from the tool back to the collector.

  • Make sure you’re maintaining minimum velocity in your ductwork; codes dictate this, but generally it’s in the 4,000 ft. per minute range (California Mechanical Code lists 3,500 fpm minimum, many publications recommend 4,000 to 4,500 fpm).  This device directly measures air velocity.
  • Options to reduce static pressure include upsizing ductwork (maintain at least 4,000 ft./min velocity…which you can use this device to measure!), increasing your filter’s surface area, reducing length of flex hose, getting more gentle-sweep elbows, and using wye fittings instead of T-fittings.
  • By knowing how much air you’re truly getting at each machine, you can really target your money towards what needs the most help.  You might discover a lower-than-recommended CFM at a particular tool is due to excessive flex duct, too small of a duct diameter, or maybe it’s just too far from the collector.  But you won’t know until you measure the airflow.
  • Dust clogs or accumulation in your ductwork? Low velocity is usually the culprit.
Sheet Metal ScrewsDust Collection Duct Fasteners
  • To connect each fitting, I use 3 hex-head, self-tapping sheet metal screws.
  • The reason I use the hex-head is because a nut-driver won’t slip and it makes it much easier to drive them while on a ladder.
  • The self-drilling feature means you don’t have to drill pilot holes first.
  • Put duct sealant over each screw when you’re done.
Duct Hanger StrapDuct Strap Support
  • There are many ways to secure your ductwork to the wall or ceiling, but these hanger straps are inexpensive, not too visible or ugly, and easy to use since all the holes allow you to position it an fasten it while on a ladder.
  • For more stability side-to-side, you can loop around the bottom of the duct and then cross over the top to form an ‘X’.
  • You can use this to stabilize vertical duct drops too, by strapping at a 45 deg. angle from multiple directions.
Dust Collection Duct Fabrication

Once you establish your design and procedures, it’s pretty much rinse and repeat after that; all joints are installed the same way.

  • Of course, you need ducts.  You can get spiral-seam ductwork (link above), or straight-seam ductwork often available at home centers.  Home center ductwork is often thin, at 30 gauge.  This is fine for systems that aren’t super-powerful, but for 3 or 5hp cyclone systems you may want the beefier stuff at 24 gauge.
  • Just make sure you buy straight ducts and fittings that are compatible with each other; buying it all from the same source makes this easier.
  • Once you buy your ductwork and choose a type, you can always buy more of it later…it’ll still be available since the different types are industry standard parts.
  • Having a plan drawn to scale will tell you how many of each fitting to buy, and how many feet of straight duct you need.
Dust Collector Dust Collection - Jet Nameplate
  • And of course again, you probably need a dust collector.  You can either go with a smaller 120V, single-stage type such as the Jet DC-1100VX, or a cyclone type such as one from Oneida.
  • We want to collect fine dust, so make sure you have a good filter bag or cartridge filter.  Most cyclones now come with “less than 1-micron” filtration, though these cartridge filters can become damaged after compressed-air cleaning, or when they get clogged particles are forced through by the fan pressure.  I prefer singed-felt filter bags oversized to compensate for the dust cake.  This dust cake helps filtration, and a singed-felt filter will retain the proper amount and the rest will fall off generally.  I have one of these and it works great, no fine dust particles anymore.  There used to be a layer of it around the collector base and frame due to the old 5-micron regular felt bag not capturing fine dust.
  • You can have more than one dust collector, so that you can have a 120V 1.5 hp take care of part of your shop, and not have to re-wire for 240V.
  • I like the Jet model because it’s what I have and I love it; it’s over 8 years old and trouble-free.  I just upgraded the filter bags but the motor’s great, and it has good power.  It gets high ratings in the woodworking magazines, too.
Dust Collection Blastgate

Each tool will get a blastgate. This one I’ve sealed the edges to help keep leaks to a minimum.

  • At each machine, you need a way to shut off the airflow so you can focus the suction at one machine at a time (except for commercial shops w/ multiple employees where the collector is sized for all machines at once).
  • Depending on your needs, you’ll want 4″ blastgates, or 5″ blastgates, or even 6″ blastgates.
  • I like to seal the edges of these with foil tape and keep the leakage down to a minimum.  Make sure the screw-closure puts pressure against the sliding gate in the direction of the airflow.
  • It’s a good idea to use bridging-type hose clamps when connecting flex hose to the blastgate flange; these provide more even pressure all around the flex duct despite the ridges for a better seal.
  • Locate the blastgates within your reach; you’ll be opening and closing these all the time, so make it convenient.  This takes some planning, so do your machine layout first before locating your duct drops.
Flex HoseDust Collection Flex Hose
  • To allow your tools to be moved around or slightly rotated, we need flex hose to connect the tool hood to the blastgate.  From there, I prefer sheet metal ductwork to go back to the collector.
  • Minimize the amount of flex hose you need such that the machine can be moved around a bit for maintenance, infeed/ outfeed needs, etc.   Flex hose has a higher pressure drop than smooth metal or PVC duct, so we want to keep the run short.
  • Depending on how much airflow you need at a tool, you can get 4-inch flex duct, 5-inch flex duct, or even 6-inch flex duct.
  • I like to run the machine’s electrical cord along with the flex hose, and tie them together with zip-ties.  For machines in the middle of my shop, I put in ceiling outlets to keep everything off the floor.
  • Some machines like Jointers and Planers with larger chips/ shavings may benefit from increasing the diameter from the typical 4″ connection.  Just make sure that the velocity doesn’t get below 4,000 ft./min.  Divide the CFM by the cross-sectional area to get your velocity in ft./ min.  You can get the CFM or the velocity by using an anemometer.
Filter Bags
Dust Collector Filter Bags

Even though it looks like a hot air balloon, the extra surface area has gained me a nice 21% increase in CFM at my planer.

  • This is a big one…we want to make sure we’re really capturing all the fine dust particles.  After all it is a dust collection system.  What’s the point if it won’t pick up all the dust?  We spend a lot of time and money to make this right so we’re comfortable, only to have the cheap filter bags spray dust right back into the shop.
  • Singed-felt filter bags are the way to go, in my opinion.  Regular felt filters get clogged easily, whereas singed-felt filters hold the right amount of “dust cake”.  This “dust cake” actually helps filter fine dust, and it’s on purpose.
  • The singed felt holds the right amount of dust, and lets the rest fall off.  These bags don’t really get clogged; they continue to breathe and filter the small 1-micron particles.
  • Ever since I installed my filter bags, I don’t see any find dust on my dust collector frame or the surrounding area like I used to with the regular felt bags.  Plus, by ordering a new one, I made sure it had more surface area then my old one to reduce the static pressure.
  • I used a lower bag that does not breathe; it’s cotton duck canvas.  You can use that or plastic; but a lower bag that doubles as a filter bag isn’t a good idea since the material will get damaged with loading and unloading chips.  Size the upper bag such that you have all your filter surface area you need up top.
  • For my Jet DC-1100 dust collector, my new filter bag has a surface area of around 54 sq. feet, including the top disc plus the sides and tapered portion.  I estimate that I’d get no more than 800 cfm for the closer tools when I upsize my ductwork (based on static pressure calcs), so the 54 sq. ft should be good.  For your shop, check the height you have above the collector before ordering yours.  More surface area doesn’t hurt by the way.  10 cfm per sq. ft. is a good target if you can fit it.
  • If you order an American Filter Fabric bag (click here), then the first number in the dimension is the diameter that goes over your dust collector barrel with a band clamp.  The second number is the diameter it flares out to, and the last number is the height; it’ll say for example: 21-Inch > 36-Inch Diameter by 60-Inch Long.  There are several size options available if you click around Amazon, or you can custom order odd shapes and sizes from them directly.  I found them very helpful.


Crayon the New Shop Cat

Crayon the Shop Cat on her way home to help with some machine set-up tasks. She takes over from Needles the Shop Cat.


4 Responses to “Dust Collection”

  1. Lou Caputo says:

    What’s the best way to ground the flex hoses that go to the separate machines?

    Thanks for all your useful info on setting up my workshop. Especially the parts about dust collection.


  2. Ant says:

    Bobby, your excel spreadsheet does not show up in my firefox browser in linux. Can you please provide a link to the file for download?

    I’m also looking at two DC systems:


    Maybe this is asking to much but will either of these work for a shop similar to your in size? They are both in my price range. Perhaps you could recommend other units in my price range. Initially my shop will have:
    15″ planer
    6″ jointer
    router table
    10″ cabinet table saw
    17″ band saw

    I really appreciate what you have done on your website.

  3. bill martin says:

    I am a hobby woodworker and building my woodshop now in my basement. I read your excellent article here and have a few questions.

    I have a Delta 1-hp dust collector with 4″ flex hose that I attach to my table saw, power miter saw, router and assorted smaller tools, like my orbital sander.

    I connect the hose directly, with reducers when necessary. Do you recommend I build metal ductwork and use small flex-hose to connect to the tools?

    It’s a very small part of my basement where I do the work. Thanks for answering this if you get a chance to.

    Your article was very helpful!

  4. Bobby says:

    Hey guys! Ask a question here and I’ll get an alert that a comment was added. I’ll try my best to respond quickly.

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