Introduction: Budget DIY 18" Cyclone Dust Separator/Dust Collector

I´m a hobbyist woodworker since some years and was happy with my Jet DC 1300 wood dust collector. But recently I noticed that I have problems with breathing after some time of sanding/sawing in my shop. Reading more about this issue I got notice of the DIY plans from Bill Pentz for a full size 18" cyclone made from sheet metal. As I can not afford the real thing from ClearVue Cyclones (which are professional built and licensed after the plans from Bill Pentz; no doubt it would be much prettier than my approach doing it almost complete by myself) or buing any another readymade Cyclone I decided to build one myself. It all started when I got hands on a brand new 4kw 3phase induction motor on ebay.

I paid 90 € (around 112 US$) including shipping for this unused electric motor so I was happy and started not knowing how it would end up. Did I do it if I had known ? Hmmm....see yourlself.

First, I´m not a professional woodworker, nor professional anything, so all I do is done with best effort, but may not be the best way to do it. I will document everything as good as I can and try to mention every error I made, too, so that you fellow builders/makers are free to grab what you like to learn or skip or ignore at all.

I bought only one other part which I did not dare to build myself (due to lack of welding/metal cutting skills) and that´s the blower housing including the Impeller. I ended up importing a chinese blower unit without motor and electronics for 390 € including shipping and taxes. The unit itself was 190 US$ so you know how much shipping was. Taxes added up to 40€ so I could easily buy a Bernardo-Unit in germany without waiting, but I did not know at the time of purchase.

That unit still was a lot cheaper than a really good quality balanced Impeller made in germany which I was offered for around 600 € (750 US$) from a specialized company.

Besides this rather expensive part (blower unit) my caclone is a budget build - feel free to build everything from scratch if you have the skills.

Enough talk, let´s begin with my first steps:

First I converted the cyclone plans from inches to the metric measurements I needed to continue.

Step 1: List of Tools and Materials

If you don´t have welding experience or equipment (like I have) you will need:


  • Pop rivet gun with around 300 of 4x6 mm or 4x10 mm Polygrip pop rivets.
    There are cheap sets available that will do fine if you have to place some rivets every once in a while, but I recommend buing a good riveting gun for this build since you need to place several hundrets of rivets into the metal. You can buy the aluminum/steel pop rivets bulk on ebay.
    (If you have big strong hands and an urge to torture yourself feel free to use the cheap gun).
    Good guns would be a Stanley FatMax MR100CG, a Gesipa NTX or for one hand use the new Gesipa Flipper which is sold on ebay for almost the same price than a NTX. Gesipa also offers pop rivets called Polygrip that have a larger range holding different thicknesses with only one rivet. I like them, but they are a little longer after the riveting on thin metal.
  • Some good HSS metal drill bits 0.1-0.2 millimeters larger than the diameter of the chosen pop rivets. Meaning 4.1 or 4.2 mm for 4.0 mm pop rivets. You may not break 4+ mm drill bits, but have one replacement handy. They cost around 1 € in a professional tool store or 3-4 € in diy stores.
  • A metal marker or marking pen.
  • Thin (metal) wire and a thick nail for marking arcs.
  • Metal cutting pliers or a nibbler for the sheet metal.
    I recommend buying an used electric metal cutter since you need to cut a lot of long and small cuts and you maybe use it in the future. The difference between a nibbler and a cutter is that a nibbler cuts out a relatively wide path (around 1-2mm) and the cutter does bend the metal a little, but the cut is clean and no material is "wasted". Use google to see the difference.
    I managed to get an used Bosch metal cutter for around 55 € but the professional grade tools easily go up to several hundred Euros so maybe a good scissor will doo, too. Don´t buy cheap tools either. Somewhere in the middle should make it, or try to rent a tool you only need for one build.
  • A jigsaw with Bi-Metal blade for the inner cutouts and a wood blade for the MDF/plywood parts. You should not use the jigsaw on the whole sheet of metal. It is messy, dangerous and the cutting line may not look good in the end. Use only for parts you really need to.
  • A bandsaw with circle cutting jig and wood blade is recommended but you may cut everything without it, too; use the jigsaw instead then.
  • Electric drill or cordless drill (or both).
  • Center punch for marking all holes that need to be drilled. Don´t need if you have really sharp drill bits but is recommended anyway to have one in your shop.
  • Free space for the sheet metal cutting and bending
  • Some hardwood square timber for bending the edges of the metal.
  • Some clamps.
  • A hammer
    (I don´t know what a real metalworker would use, I used a simple heavy but small mullet. You know the rule of thumb: if the hammer is not the right tool, use a bigger hammer.
    Just joking.)
  • Pair of gloves. Freshly cut metal has sharp edges.
  • Protection goggles if you use the jigsaw for metal cutting.
  • A pair of helping hands here and there. I tend to do all alone, but you need good anger management this way.
  • Tea or Coffee or both, lots of cake, good music and whatsoever you need for a good shop session.


  • One piece of sheet metal measuring 2500x1250 mm or 3000x1500 mm or
    two pieces of sheet metal measuring 2000x1000 mm
    Should consider buying some more to take credit for wrong cuts or experimenting with welding, making some ducting parts or whatever. It´s relatively cheap.
    I paid 33 € (42 USD) for the 2,5x1,25 m galvanized sheet metal at a local metal dealer. Don´t buy this in a DIY center, because you will spend much much more easily and the sheets are mostly 0,5x1,0 m and too small.
  • For the motor mount use Plywood. The size depends on the size of your motor and how you like to mount it to the wall.
    Since MDF is not really strong you should only use MDF for things with lesser weight on it. I used it only for the mounting plate of the motor.
  • For the dust collector bags use four sheets of wood measuring 55x55 cm (or the size of your cartridge filter outer dimensions +5 cm); 18mm+ plywood is best for overall stability, 19+mm MDF will do, but no OSB or particle board is recommended.
  • Two filter bags sizing approx. 50x150 cm of good quality with 50cm diameter hose clamps or....
  • It is strongly recommended to use two big cartridge filters stacked on top of each other but this will blow the budget by another 400+ € (without shipping). The bags are around 30-50 € each and you need a two way vent and more room to place them side-by-side. I documented the bag version since I don´t have the money yet to buy the good quality filter cartridges. I planned to replace the bag version as soon as possible. I know this is limitting my air flow but I think the performance even with the bags will be much better than my old 1300 qm3/hr Jet blower anyway.
  • Lots of screws, wood glue, aluminum plated sealing tape, ....

    See the webpage of Bill Pentz for a detailed analysis and description of everything. I truly want to give him credit for his great source of information and plans he offers for free. Take a look and see for yourself.

Step 2: Parts List and Layout

I´ve done some Sketchup renderings with the converted measurements in metric sizes.

Don´t be bothered by the ugly 0.x mm measurements, you can surely round up/down where needed because I think this is no rocket science and everything can be made to fit within the specifications while working on it. Hey, we are using pop rivets for the connections instead of solder/welding joints.

I recommend that you see Bill Pentz pages first to read about what I may miss to tell:

Cyclone and Dust Collection Research by Bill Pentz

I don´t know if anyone needs the Sketchup file but I will give them to anyone interested.

Step 3: Cut It

Put the sheet of metal onto a solid worktable or supports. Decide how to layout everything that it fits on one or two sheets depending what sizes you have.

Use a scribing tool or marking pen to mark every cut line and every bend line to reduce errors while cutting.

Cutting with the electric cutter tool is fun. On the picture above you can see my first buy - a very old electric cutter. This one only did 10 cm of cutting after it went up in smoke - the second one (bosch tool) is working fine since I bought it. So maybe not EVERY old tool is good even if it is really heavy.

Keep caution on the edges, don´t cut too deep since you need to seal every hole later somehow.

Pop riveting alone does not make a good seal.

Step 4: Mark It

Since I wanted to connect every part with pop rivets I needed to have an idea how to do it.

So I decided to use the original match lines from Bill Pentzs´ plans. They will be the lines where the holes for the rivets will be placed.

I decided to have a spacing of 2.5cm for each rounded fitting and approx. 5 cm for the non-bent parts. I decided further to not think about how to get them air tight later. Damn. But more about that later.

Hey, this is an Instructable. I´m a maker. At least that´s what they tell me.

After marking use a center punch and a small hammer to put small dents into the metal. You use them to help center the drill bit. I recently found out that you don´t need a center punch if you have good drill bits that have a special cut so they will center themselves, but I forgot how they are called. I will update this if I find out. So if you have the choice buy the better drill bits and save a lot of work.

Step 5: Cut the Saw Teeth

On every metal part you cut or drill you should use some lubricant to prevent early tool death by fatigue.

It keeps drill bits longer sharp and last longer and helps even cutting the metal.

The electric metal cutter uses two small carbide blades that shear against each other to cut the metal, so it will bend a little downwards when the lower arm holding the second blade goes through the cut.

The teeth-like cuts are made because they must not touch each other when the cylindrical parts are bent later.

So all parts that get bent will be cut in shape of "saw teeth", don´t mind the other ones. I didn´t think about this, because I thought them to be bent, but they didn´t need to. See the later pictures for clearing up this mess.

Step 6: Drill It...

After marking, center punching, lubricating, cutting, you need to drill a lot of holes. I pressed the sheets together with two parts of scrap wood and some clamps.

Use the 5.1 (max 5.2 mm) drill bit if you use 5mm pop rivets, or 4.1 (max 4.2mm) drill bit if you use 4 mm. But I don´t need to tell, don´t I ?

After that clamp the parts that are connecting the cylindrical bent parts together tight into two squares of hardwood. I used screws, too, because my clamps did not bring the required pressure to withstand the hammering force and slipped.

Step 7: Hammer Time !

Do this to every part that connects to another part. Squeeze it into the hardwood, hammer the saw teeth.

The parts that connect the cyclone cylinder with the bottom don´t need to be bent 90 degrees, instead only use a light hammering to bend them to around 20 degrees. This can be fitted later when connecting the parts.

Step 8: Over and Over Again

Repeat for each part with pop rivets in it.

That will be every part.

Man, that are many holes, rivets, teeth.

Hope this will work as hell ... later ...

Step 9: Bend It

If you don´t have a bending unit around you need to improvise.

I did cut some circles of scrap wood measuring the inner size of the cyclone body.

Bend the metal roughly over some thick tubing or tree but try not to make dents into the metal. If you already did try to hammer them straight but don´t overdo it. I think this will be no problem unless you have some serious 20+ degrees hard edges in the tubing after bending.

Start with the big cylinder to get a feeling for it. I drilled two small holes through the metal so I can put a screw into the template wood circle to fix it.

Then I used regular spanning straps to slowly bend the metal around the wood circles until the ends overlap each other. If you have measured everything right the holes will match the ones on the other side. If you don´t did it right, it overlaps far more than it needs. But that´s fine, because the tension in the metal will bend it back anyway so it´s no problem if you have circles a little bit smaller than necessary.

If necessary use an third strap to tighten the diameter while loosing the two other ones in turns and retighten them until the wanted diameter is reached.

Clamp both ends together with a pair of crimping pliers and set your first pop rivets after removing the wood out of the cylinder.

Step 10: Pop It...

The moment of truth.

Everything drilled right ?

Measurements fit ?

Metal softly rounded ?

So put your first pop rivet in the gun, stick it through, try to fit both sheets of metal tight together, pull the lever of your gun, BAM !

The Polygrip rivets may need a second pull on the handle to cut loose because of the bigger clamping range.

Every other rivet type may need only one pull. Do one after another beginning either top or bottom, but don´t switch, because you could bend the metal and make it less tight than it should be. If you forgot to cut the hole for the Inlet port you need to drill out the rivets and start over after...


I forgot the port hole. Goto 10. Start over. Drill out the rivets with the same drill you use for the holes, pop out the rivets.

Next step.

Step 11: Don´t Forget the Inlet Port Hole

That´s DIY. Isn´t it ? Trial and error. Learning by doing. Don´t think about it. Keep up, take a nap, have another coffee or tea, mark the cutout, measure twice (cut once).

Bend it with a pair of pliers so that the vertical inner teeth show into the cylinder, the top and bottom ones to the outside.

The outside vertical ones don´t need to be cut anyway because they will fit flat onto the port. Insert the inlet port, fit it properly and drill the holes through. Pop rivet as ever. You should seal the gaps with whatever sealant you have (silicone, bitumen...).

Step 12: Filter Bags

I bought 2 filter bags from cotton which is the cheapest, but the worst solution, too. Cotton lets through the fine particles and clogs really fast, but I hope because of the cyclone only the really fine particles get through anyway and clogging is not so heavy as expected.

I really want to update this to cartridge filters but you need to invest another 400-600 Euros into them and I currently don´t have it.

First I cut two discs measuring 5cm more than the filter bag outer diameter and two more measuring just as much as the filter bag inner diameter, which in my case was 50 cm. The second two discs need to become rings so I cut them from the inside with my tablesaw on a circle cutting jig.

Because the filter bag needs to fit over it I rounded all edges with a roundover bit and a plunge router.

It will look nice, too.

Glue everything together and bolt it to the base plate. Now I needed to decide how the bags will be connected to the output port hole.

I had to connect the bags to the blower housing so I took an unused 150mm-T-fitting and two 45 degrees bend pipe fittings. This is not really optimal because I restrict airflow to 150mm diameter instead of 2x150mm because everything is going through the "bottleneck" but what the heck, I want to finish this thing and can change this later.

Maybe I win the lottery and can afford two cartridge filters.

The ducting needed to be connected to the filter bag holding plates so I cut two more discs and made rings that fit barely around the 150mm hoses. I glued them together with hot glue and tightened them with power straps until everything cooled down after a few minutes.

So I needed to cut holes in the base plates and decided to do it the dirty way. I cut two forstner holes into the middle of the plates and screwed the 150mm ports on top. Using a straight cutting bit with bearing guide I widened the holes to the exact diameter of the duct fittings. But - since the metal is bent on the edges - cut some metal of the fitting with my expensive router bit. Shit happens. it should work fine on MDF still, but I think it´s not longer sharp enough for hardwood.

With the bags came two metal belts with clamps but they didn´t fit over my custom built MDF rings so I needed to cut out the old pop rivets and drilled two new holes with the new diameter. Fortunately the belt was long enough to add another 5 cm to the diameter.

After that everything could be connected to the blower housing.

Step 13: Dust Bin

I bought a used water barrel cheaply but it was to high fitting under the cylone (damn, this thing is very long... I did underestimate it before buying the barrel).

But since I didn´t want to buy a new barrel (and finding one thats wide enough but not high is difficult) I decided to shorten it a little by cutting out a slice of it and joining the remaining parts together with 2k-epoxy and fiberglass to reinforce it.

I know, it is made from plastic and should be grounded and this is what is missing on the pictures yet.

If you can use a metal barrel for the dust bin!

After cutting the barrel I drilled several holes through the top and bottom part of the halves and used some scrap cardboard to connect both halves together from the inside. As it turned out this did not work out, because my barrel was a little bit thicker on the bottom so a small dent appeared and I did remove the cardboard.

I cut some slots in one half of the barrel to squeze one half into the other just that it overlapped a little to screw them together from the outside.

After laminating the cut line with stripes of a glassfibre mat I cut the screws with the angle grinder.

It does not look really good, rather really ugly, but it is stable and I hope will withstand the pressure of the blower.

To ground it I will insert some bare copper wire around the bottom of the barell and on four sides on the wall to the top and connect them through flexible copper wire to the cyclone, which itself is grounded to our houses "potential equalization" (I really don´t know if this is the right word) to prevent electrical sparks ignite the wood dust. It could result in an really big bang if the wood dust ignites and blows up the barrel so be carefull to electrically ground everything.

Step 14: Duct Work

If have gone this far you know it is not over yet.

Your old 100mm duct work will not longer be sufficient so every duct needs to be replaced.

Since this is not the theme of this Instructable I only put up some images to your further reference. Feel free to check them out to see what you can do.

I used some aluminum plated sealing tape and self sticking aluminum tape to seal every connection. Since this is a budget solution for dust collection I only bought the cheapest duct parts as you can see, they don´t seal very good for themselves (picture 2).

If you don´t seal the tubing your cyclone may loose too much power on all the small holes sucking air in and not sucking dust at the point you create it.

So please be carefull. Or buy the ducting with pre-fitted seals which is much more recommended - but much more expensive, too.

Step 15: Electric Works

A motor this powerful can´t be started instantly. So I got hands on a used soft start module.

These are relatively expensive when bought new (around 400 €) but you can get them used for under 100 € if you are lucky. The chinese built blower use some kind of magnetic switch things but I don´t dare to "jump start" a 4 kw 3p-motor so I decided to play it safe.

You can configure starting time, starting current and breaking time and this is fine for me.

The other device ("Frietomat") I bought some years before for my old system but never had the time to install it properly. It is used for switching on the dust collector when you start your table saw (or other devices connected to it).

It uses a coil to measure electricity that goes through the power cord. If you switch on the machine, it induces current into the coil and the "Frietomat" switches on the dust collector.

The problem is that this device only can start up 1p-220V devices and not 3p-380V ones like my blower motor.

Since my soft start module has a separate input for start up where I can put 220V on I can connect them together, but this is another story.

Please take notice that every device like this should be connected and checked by an electrician! Don´t touch this if you have no idea what you are doing.

The pictures taken from the blower motor connected to the soft start module are only to check the function of the motor and the unit and are not the final result so cabling will be done properly later.