These instructions presume you are starting with little to no sheet metal skills and a minimum of tools. As of the beginning of 2007 there are now over 4,500 cyclones that exactly follow my design in use with over 2000 woodworkers having built their own cyclones from these plans. You can do the same if you will take you time, be patient, and follow along. Please read the Cyclone Plan page before starting on building your own cyclone. Additionally, if you don’t have any experience doing metal working, build yourself your cyclone out of poster board and that 3M blue masking tape. You would be amazed at the numbers of people who write and say they transferred the dimensions wrong, left off tabs, etc. that resulted in their having to go buy additional metal and remake some of their parts. A cardboard cyclone where all goes together correctly will not only help you figure out all the different parts, but when this cardboard model is done, you will have a template that you know is right and will work for your metal working.

Most of the pictures on this page are very small thumbnails you can click to get full sized pictures. This lets the page load faster for those with slow connections.

Before starting you should decide on the material for your cyclone. People have made my cyclone design from quite a variety of materials. Most make their cyclones from galvanized sheet metal, but there have been quite a few other approaches. A few started with cutting up 55-gallon drums. Some used bendable plywood. One used graphite fiber. Another used vinyl floor covering. Some use fine hardware cloth (wire mesh) that they then coat with fiberglass, epoxy, or even spray with truck bed liner. One even made his cyclone out of concrete on a fine steel mesh. I even made one out of large PVC pipe. Frankly, almost any material will work if the result is strong enough to handle a minimum 15” of vacuum. I prefer to design my units to handle at least 22” of vacuum which is about what it takes to flatten typical galvanized steel HVAC snap lock pipe. I found using sheet metal is least expensive and quickest. Probably the prettiest is to use clear high impact plastic. With plastic being slicker than metal, it actually does a better job of separation, but can build up static charges. You also should pick a material for your cyclone body that will last and can stand being constantly sandblasted with hot wet sand. Many woods have a high silica content better known as sand and when this dust slams into the cyclone it releases moisture and generates heat. Blasting with damp warm sand causes many commercial cyclones to rust and wear through right at the point where the incoming air hits the outer cylinder wall. That is why I recommend making your cyclone from plastic or protecting that first contact point with either a rubber sheet or coating like truck bed spray on liner. These plans assume use of sheet metal and you are willing to learn a little basic metalworking.

Building your own cyclone is not a particularly difficult project, but does require about twenty hours work for those who are not familiar with metalworking. Most of this time goes into forming the metal carefully without using special metal working tools. Those who have the normal sheet metal brake, roller, and beading machine can make their first in about ten hours then only need about five hours for each additional cyclone after making their templates and refining their technique. A commercial ducting shop with powered sheet metal tools can typically cut and build one of these from the laid out metal in about two hours which is why many end up having these plans built for them at metal shops.

The key to building a cyclone that fits together easily and well is ensuring that you have the spreadsheet properly configured for the cyclone you want to build, carefully layout the dimensions on poster board, measure and cut accurately, and then after working out all the bugs on that cardboard, use that poster board as your templates for cutting your metal, and finally work the metal to fit well using templates to hold things round and the correct size..

1. Template Rings - These plans depend on use of carefully made wooden template rings to ensure all comes out the right size, that all the round parts stay round, and that all will fit together. Using the rings ensures all will fit right on. Those who do not use template rings during inlet, cone, and air ramp installation and soldering invariably end up with junk having to start over because they either cannot install the top ring or mate the cone because the cyclone goes out of round. The rings also help you avoid problems making joints in the wrong places. You need two round 18” diameter rings to help size and keep the upper cylinder and top of the cone round. These two rings keep the cyclone upper outer cylinder from warping or going out of round while installing the inlet, air ramp, and cone. One or both of the two 18” rings can become part of the finished cyclone holding the cyclone outlet and providing a place to mount the blower. A pair of 9” diameter rings is needed to similarly size the air outlet and keep it round. One 6” disc helps size the cyclone dust chute, the cyclone inlet transition, and the blower outlet transition. This same 6” ring later serves as a plug to check our cyclone for leaks.

2. Cleaning - No matter what approach you use to build your cyclone, it is best to first clean the metal thoroughly. I found using lacquer thinner with constantly changing rags did a good job removing the coat of oil used on sheet metal.

3. Metal Seams - The seams join the cyclone inlet into a rectangular box, the cyclone top into a cylinder, the cyclone bottom into a cone, and the halves of the dust chute. My design allows you different approaches to make these metal seams. The 3/8” extra wide tabs on each side of every joint can be seamed, overlapped or bent out at 90 degrees. Seamed joints are similar to the joint used on the top of a metal food can and require a special and expensive joiner. Making the bent seams is easy and you can hide those seams with automotive door trim, but most choose to make overlapped joints that look nicer from the outside. You also can hide your seams by putting them at the back of the cyclone so they do not show. If you choose to make overlapped joints, remember my plans use tabs on both sides, so you need to center the dotted lines to make joints that are twice as wide as either tab. Use of the rings for sizing will ensure proper sizing and joint alignment.

4. Fastening Seams - There are also many ways to secure the seams. Going from easiest to hardest, you can use a spot welder, screws, pop-rivets, regular rivets, soldering, brazing, and welding. Each requires different skills and tools. I've made units with a MIG welder, spot welder, screws, pop-rivets, and solder. My design is optimized for solder but works well with either screws or pop rivets. I think soldering works best making the nicest looking finished unit. Here are some of the approaches in order of preference and nicest finished result that you can use to build this cyclone:

   1. Soldering:
      Soldering is the method that I share here because it produces the best looking and strongest unit possible using readily available and affordable tools. Soldering is not for everyone, so I strongly recommend doing enough practice to decide if it will work for you. Also, if you have not done quite a bit of metal soldering, it is well worth your time to read over the below "Soldering 101" instructions. If soldering is not your thing, then go to the pop-rivet or screw type construction with polyurethane caulk. Either will serve you well. One of the biggest problems with soldering is most today simply go to their local “box” store and buy solder and flux. The non-lead solder they get with its flux is mostly not compatible with today’s “zinc” plating used on galvanized metal. Today many other metals are added to plating to make for longer lasting material that often can self-heal from small scratches. These additional metals used in protecting steel require a special flux and solder compatible with today’s plating because normal unleaded plumber’s solder and flux will not stick. I have had excellent success soldering all different types of galvanized coatings using 50% lead based solder with All-State Welding Alloys, Co. Duzall flux. Although a 4 oz. bottle is ample for a couple of cyclone projects, I order the 16 oz. bottles because with shipping the cost is nearly the same for four times as much. Only one of the many local welding supply outlets in my area carries this flux, so I ended up going on-line to buy mine, e.g. www.weldingsupply.com.
      
      Caution: Zinc, which is used often with other alloys like cadmium to galvanize steel is toxic when heated to a vapor and so is the lead in our lead based solders, so you need to work in a well-ventilated area and wear gloves. I prefer to do my soldering outside with a mild wind blowing or using a fan to blow across the work to minimize my exposure.

   2. Seamer:
      The fastest way to build this cyclone is to enlist the aid of a local duct maker and use their seaming machines. Duct workers have long worked with metal of this gauge to quickly make strong tight joints. In 2000 my local firm charged me $75 to roll all the metal and then make every joint except the air ramp. In 2008 this same firm now charges $200 for this same work. My firm was kind enough to let me watch. I thought I was pretty good at building cyclones because I had made quite a few. They really badly put me to shame. Their entire effort took less than an hour and left a pristine near perfect looking cyclone. Their eight foot long power roller rolled all nice and round including a perfectly tapered cone. Their LockFormer machine made snap lock joints for all the straight edges. They also had a special seamer that made the cyclone center joint between the cone and cyclone top, sealed the inlet to the outer cylinder, plus it put the rings on the bottom of the cyclone and both transitions. To use these machines I had to make all the tabs grow from the 3/8” in my plans to a full 3/4”. My metal workers advised that there are quite a few different joints and levels of these joint forming machines, most of which require different length tabs, so check before cutting any metal to be used with automated seaming equipment. All of these joints still required being sealed with a polyurethane duct sealant.

   3. Screws & Pop-Rivets:
      The easiest homemade way to build this cyclone is to use screws or pop-rivets. You can screw or pop-rivet the outer cylinder, the cone, the cone-to-cone outlet, and the air inlet. I've left plenty of material so you have room to drill and install pop-rivets or screws. I found 3/16" long rivets work well as they almost totally vanish on both the inside and out. All require lots of polyurethane gutter caulking. The Wood Magazine plans that you can purchase on-line for just a few dollars do an excellent job of showing you how to build and hang a cyclone using pop-rivets and wooden rings, plus shows you their way of hanging the cyclone. I do not recommend using their cyclone design, as it is very inefficient and the sheet metal too thin. I helped them upgrade their cyclone design so it has more efficient airflow, but these cyclone plans still provide almost no separation for the airborne dust that clogs our fine filters, so I only recommend venting cyclones made from these plans outside rather than use them vented indoors with fine filters. These plans here work equally well when using screws. The big difference with screws is you need to drill a larger outer hole and smaller inner hole. Hand tightening the screws will then pull the inner metal tightly to the outer. You still end up having to grind off the screws inside the cyclone to keep strings and shavings from hanging up on the screw threads that stick inside the cyclone. Joining the top cylinder to the cone and cone to the dust chute requires wooden rings, bent over tabs, or find a sheet metal shop that can roll a lip. I think bending over ½” tabs is the easiest and ends up with the best looking result.
      
      Start with drilling a hole at the center of the joint using a backer board. Next drill a hole on either side of the first hole spaced no more than 1" apart. I made myself a metal guide so my screw holes all line up. Without a guide you need to drill a set of holes, temporarily secure then drill the next hole and secure. Remember, if using screws then drill out each outer hole a little larger. Next run a bead of flexible polyurethane gutter and flashing caulk on one side of the joint. Clamp the pieces together in the proper alignment tightly on the form rings. Start by putting the first screw in the center of each joint then work outward going on either side. This spacing and working from the center out makes for a nice clean joint without any wrinkles that are inevitable if you don't work from the middle outward. I used to recommend putting the screw heads inside, but it was just too hard to provide good access. It is better and easier to put the screws in from the outside then grind off the heads later. For the pop rivets put the head inside which means you have to put in your riveting tool inside which is a little cramped. Remember the airside for the cyclone outlet is the inside of that cylinder. After securing and the sealant dries, put a piece of heavy aluminum duct tape over the inside of each joint. This makes a cleaner joint in terms of less air resistance. Using screws and pop rivets makes for an uglier cyclone exterior, but where it counts is on the inside. There we need as smooth and flush surfaces as we can get. Automotive door edge trim will snap right over the tops of the rivet heads it you want to dress them up some.
      
      Screws and pop rivets work well, are easy, and do not require a lot of practice or special tools, but makes for such an ugly looking cyclone I don’t recommend either.

   4. Spot Welding:
      One of the nicest ways to build the cyclone is to use a spot welder. You can buy a used Miller tong type spot welder on eBay for about $200 or get a new one from Harbor Freight for about $160 on sale. The Miller 18” tongs fit either unit and you need a set of these for roughly $90 to reach in deep enough to weld the cone. I have heard of groups who went together to buy or rent a spot welder. It takes some practice unless you get a welder that lets you setup an automatic weld to ensure the spots go deep enough without burning through, but the result is quick and looks pretty good. Again you will need to seal the inside with sealant and the aluminum duct tape. I personally use a combination of spot welding followed by soldering to make the cyclones I build today.

   5. MIG Welding:
      Another technique uses a wire fed MIG welder with either light or heavy sheet metal construction. Again, I do not have the skills to teach that type of metal working, and most do not access to an appropriate welder.

   6. Heavy Duty Welding:
      Finally and perhaps the strongest way to build a cyclone would be to use 16 or 18 gauge metal, a professional heavy sheet metal fabrication plant, and all welded seams and joints. My cost locally to do just that was nearly $400 to pay the $80 an hour my local firms charge to do TIG welding. The results are beautiful but going a little overboard. Careful MIG welding does an equally fine job and is used on at least one commercial hobbyist cyclone.

5. Clamping:
   A vital key to good joints is tightly holding the joints together. There are lots of approaches to clamping. Here are a few I tried including the only two that worked for me:

   1. Metal welding clamps:
      Like most woodworking, the key to good joints is making sure the joints fit right on instead of trying to force things by using heavy clamps. Unless you know what you are doing, using the long vise-grip type metal welding clamps creates nothing but an ugly mess of dented up metal and poor solder joints. The clamps are too much of a heat sink making it impossible to get solder around them without constantly changing clamp position or running a torch way too hot which will burn off and melt the galvanizing. They require a gentle touch or using homemade aluminum clamping pads to clamp without using so much force that the clamps bend or dent the metal. These clamps are also are so heavy that their weight alone will bend the metal if the clamp weight is not supported. To make these types of clamps work, you need at least three long reach clamps, each with the wide articulated pad that provides a flat clamping surface instead of the rounded point type clamps plus aluminum pads to spread the clamping pressure down our joints instead of in a small circle. I made up my own clamps with 3” wide long pads. For those who use normal clamps, I found separating these clamps by about 1” is ideal, so instead of a few we end up needing more than a dozen. You can “leap frog” the clamping by starting at the center then using two pairs of clamps working outward. Secure the area between two clamps, then move one clamp outward and secure the new area. If soldering we end up having to heat the whole area including the clamp enough to get the solder to flow. This is a pain and can easily cause burns if you are not real careful when moving the clamps. When using clamps we are also relying on them to provide a bit of a heat sink. This means that as we heat up the next area our clamp is going to keep the just soldered area from getting so hot the solder melts there too. Anyhow, unless you carefully formed the joint to be tight and only use low slow heat when soldering, the metal will warp, you will “un-solder” previously soldered areas, and . Most end up putting in screws every 1”, soldering, then removing the screws and with the clamp to act as a heat sink patching the holes. I personally use a spot welder rather than either clamps or screws to try and hold all together.

   2. Temporary rivets:
      I tried what many others do following the Wood Magazine plan using aluminum (not steel) pop rivets to do the holding while soldering. They work ok, but not well. Drilling them out after is a real pain because the metal that flares the rivets spins unless you use something like Vise-Grip pliers, plus that metal shaft is so much tougher than the rivet body, you often end up drilling through the side of the rivet into the cyclone metal. .

   3. Self-Starting Sheet Metal Screws:
      I even tried self starting 3/8" long sheet metal screws. These screws are built to be driven into sheet metal by a drill driver and will strip out easily. Although these screws work well for many applications, they cost a bit more and did not pull the metal together tight enough for good solder joints. The only way I found to make them pull the metal tight enough together for soldering was to pre-drill a hole larger than their threads on the top piece of metal. Then use a drill to drive the screw into the lower piece of metal stopping before the screw pulls in. Finish by hand with gently pulling the pieces tight and not stripping the metal. With that much work, it was cheaper, easier and much faster to use a single sized hole and pop rivets.

   4. Regular Sheet Metal Screws:
      I found using Phillips head sheet metal screws makes it much easier to remove them later to fill the holes with solder. As with the self-starting sheet metal screws drill the top piece of metal with a hole larger than the threads and then drill a small starter hole in the bottom piece. These sheet metal screws work better than the self-starting sheet metal screws because they have a much bigger taper that will really pull that bottom piece tightly to the top before stripping. The secret to removing the screws after soldering is to ensure you do not solder over the heads. Lightly heat them while your screwdriver is applying pressure. When they give stop the heat and unscrew them.

   5. Big Jig:
      I had so much solder leak through on some prior efforts that I came up with a jig to hold the metal tightly together without holes! This is way too much work unless you were to make a lot of cyclones. A jig works well until you do something stupid like me and loan the jig out and it never comes home. I made my jog from two pieces of heavy angle iron with one flipped opposite the other. I clamped them together with about 3/8" overlap, then drilled and tapped for 3/16" bolts. On the ends I put in 1/4-20 bolts with spacers to hold the two pieces together in alignment. These end screws keep all the other screws aligned opposite each other and hold the two pieces of angle iron off the metal. I used surplus stainless steel thumbscrews because the stainless does not conduct the heat away from the joints like steel welding clamps do. Stainless is a natural insulator, so the screws do not act as heat sinks, plus most solder will not stick to these screws.
      
      Use is fairly easy. Use a straight edge and extend all the thumbscrews about ¼” to make an even row. Put the angle iron over the joint to be soldered, tighten the 1/4-20 end bolts firmly on their spacer, then lightly tighten the thumbscrews starting from the center working outward. Again, having a joint that already fits tightly is critical as these are not going to pull a poorly made joint together. They only hold the joint together for soldering. The stainless screws act just like pop-rivets or your sheet metal screws in terms of pulling all the joints together tight with no holes to fill.
      
      Also stainless does not stick well to solder. At first I tried a 4" to 5" spacing, but recently remade my jig with screws every inch. That also lets me use my torch to solder quickly. If you were going to make a few of these, making a jig is well worth the trouble and you will spend less time making the jig than filling and sanding holes with solder. Whatever technique you use, the goal is to start with the joint made tightly, then hold the pieces in place because solder is so thin when melted it will flow right through any gaps.

   6. Spot Welding:
      Other than going to a sheet metal shop that has powered seam making equipment we found a spot or MIG welder is the fastest way to hold our joints together tightly in preparation for soldering. I prefer a spot welder, but found that by drilling holes on just the outside of our joint, clamping the whole joint together, then a light tough with the MIG left a nice weld that held all together well for later soldering. I found my MIG just does not have the temperature range to be good at welding thin galvanized steel, plus put out a lot of very toxic smoke so required me to be in my welding helmet with its built in respirator. A spot welder saves a lot of time drilling and putting in either screws, rivets or other types of fasteners without the large amounts of toxic fumes. My son and I still make a few cyclones for friends and we use a spot welder then solder. We prepare each joint with metal cleaning acid flux, tin both sides of the joint with solder, use ½” HVAC worm drive stainless metal duct clamps to hold each piece solidly to its wooden form, then using a spot welder with the long tong arms weld going from the center out to avoid wrinkles. We then solder the joint making for a good airtight seal.

6. Soldering Heat Source: Soldering works best with a propane torch or MAPP gas torch, but can be done with a big soldering iron. The soldering guns are not big enough. It takes at least a 150 watt soldering iron and works better with at 300 watt iron that does not lose so much heat in use. A few terrible early propane torch failures led me to recommend and buy a big expensive American Beauty soldering iron. Since then I have improved my propane torch technique and now have a couple of those expensive big soldering irons available cheap. Unlike a monster soldering iron, I can always find a use for a good torch. Don't follow my early lead and use your torch on too high of a setting as that leads to bad metal warping and burning the zinc coating which releases some pretty toxic gas. Instead use a very low flame and keep the torch moving back and forth over at least 3" area. Soldering takes lots of patience, but is worth it!

This is another one of those. I took it for granted that most knew all about soldering. Based on some of the pictures I got back, I screwed up badly. There are lots of ways to solder and most can be made to work, but here are a few pointers for your practice pieces than can make a world of difference and use about 1/3 as much solder. I strongly suggest that you work with some scrap pieces to get your technique down.

1. Mark the center hole and drill 5/32" holes along the same edge that your will overlap on the upper cylinder.

2. Form the cone. It seems to work best to work the whole cone into a relatively tight cylinder around the 4" pipe using a clamp then open it carefully to the right shape. You may need to use the PVC more to work the bottom into the right shape as narrow pieces of metal are harder to form.

3. Work at forming the cone and getting it just right so it will stand on its own (See picture above).

4. After forming, cut ½" wide tabs each ¾" long on the large curved end to mate with the upper cyclone cylinder.

5. Cut ¼" wide tabs each ¾" long on the small curved end to mate with the dust chute outlet.

6. Place the solid 18" disk template on your work surface.

7. Clean, scuff, and put on the flux.

8. Make sure the joint is aligned so the airflow falls over the joint overlap instead of ramming into it.

9. Mark the hole closest to the middle.

10. Put the cone wide upper end down on the template and secure it with a screw clamp snuggly. I used a regular stainless steel 1/2" worm drive screw type screw clamp to hold the disk tighter. I made my 18” worm drive clamp by taking apart three 6” clamps and screwing them together. These 6” clamps can later be used on 6” flex hose. Note in the picture that I made little metal tabs that hook onto the clamp metal to keep the template from slipping out when the clamp is tightened.

11. Do the same on the bottom with a just under 6" disk template clamping snuggly. I made a wooden cross bar that holds my wooden 6” template in place so when clamping the clamps do not pull the template into the cone.

12. Ensure both templates and cone ends are flush.

13. Start in the center then drill with the 3/32" bit and a backer block. Screw this joint together again working from the middle outward to keep the joint smooth and tight.

14. Solder the joint. Remove the screws and sand off any burrs.

15. Sand or scrape flush.

16. Remove the 18" disk template.

17. Bend the tabs on the top and bottom of the cone as needed.

1. Mark and drill 5/32" holes on one side of the outlet seam as you did before.

2. Form the outlet as you formed the cone and cylinder. This one also seems to work best by squeezing the whole cylinder smoothly around the 4" pipe using the screw clamps then open it gently to the right size and shape.

3. Scruff and clean the joint areas to be soldered then put flux on both surfaces.

4. As you did with the big cylinder clamp a 9” template ring flush on each end.

5. Working from the center out, drill 3/32" holes and screw the joint together.

6. Solder the joint, remove the screws and fill the screw holes.

1. The ¾” tabs on the bottom of the cylinder should be bent out as shown in step 2 of the above diagram. Likewise the 3/8” tabs on the cone should be bent out as shown in the same step. The wooden lower ring should still be clamped tightly in the cylinder and raised up from the bottom.

2. Flip the upper cylinder upside down with the tabs on top.

3. Put flux on the upper cylinder tabs and on both sides of the cone tabs.

4. Now bend these tabs with another 90 degree bend as shown in step 3.

5. Rest the cone inside the upper cylinder tabs. Align the tabs so the cuts are not over each other.

6. Bend the upper cylinder tabs over the cone all the way around. Then use a pair of vice grips to squeeze the joint tight.

7. Solder the joint from the top, then flip over and solder the other side.

8. Remove the sizing ring. If you do not remove the sizing ring now, getting it out with the air ramp installed can be a challenge requiring ruining the ring by cutting it up with a jig saw into pieces small enough to be removed.

Making up the cyclone outlet, soldering the air ramp to it, and then working to make it fit to the outer cylinder causes problems if you don’t understand three things.

First, even with a good brake and wooden templates, getting an outlet to match right on is near impossible. Worse, any error gets squared then multiplied by Pi, so even a tiny difference becomes a big gap. Rather than try to require all pieces to be made perfectly, I’ve allowed for some extra clearances and use sizing rings to ensure consistency.

Second, if you don’t use your sizing rings on that outer cylinder any errors are going be multiplied by Pi leaving almost no chance of being able to later install that inner cylinder that serves as the cyclone outlet or be able to attach the cone because your cylinder will be far out of round. Failure to use the rings also seriously hurts cyclone performance due to poor internal air flow.

Third, the air ramp is not a perfect fit and was never designed to be a perfect fit. I traded emails with the professor at Cornell who shared the math used to calculate the air ramp sizing. To be a perfect fit requires not a flat donut shape but instead a curved conic shape which requires metal expansion. To make our flat metal ring work without the required special metal forming tools what I did was make it so the air ramp fits tightly to the top of the air inlet and tightly to the inside of the cyclone outer cylinder. The air ramp is not supposed to fit tight to the cyclone center outlet tube or flush with the bottom of the inlet. The air ramp is designed to create a wedge shaped hole between the bottom of the inlet, the air ramp and the side of the cyclone. This hole is required if we want the air ramp to fit nicely without warping. This hole also allows a way for the inevitable dust that gets inside the dead area enclosed by the air ramp to escape.

I used to recommend using a rubber gasket to help seal close to the cyclone center outlet cylinder, but that joint does not need to be sealed, smooth or air tight. Make sure you do not use sealant on the center joint or you may never be able to take your cyclone apart. We need to be able to take the outlet cylinder out to clear a plug or board stuck in there sideways.

1. Check your dimensions against your intake to make sure you have a snug good fit.

2. Scruff and clean the joint areas to be soldered.

3. Make sure your outer cylinder is still marked all the way around with an easy to read dark line showing where the air ramp will touch that outer cylinder.

4. I think the best way to install the air ramp is to pull it tight to the top edge of the inlet and tight against the adjacent cyclone outer cylinder wall then either solder, screw or rivet it in place to the top of the inlet. Stretch it out so it makes one full turn around the cyclone outlet cylinder. With that top secured and sizing rings in place, then expand the air ramp to make a tight fit to the outer cylinder wall by pushing the bottom of the air ramp toward the bottom of the inlet. You want a nice even contact without warping. Then secure the air ramp to the cylinder wall and to just the inner most edge of the inlet. After soldering I use caulk to make a smooth joint and seal that connection between the ramp and outer cylinder wall.

5. Attach the spiral down the outside of the outer cylinder either using solder, HVAC sealant (recommend Eco-EZ Seal 44-39 High Velocity Sealant), polyurethane caulk, or good 3M automotive urethane windshield sealant. The result produces a nice airtight joint. Don't use silicon caulk because over time it reacts with the metal creating acetic acid and then falls off.

6. Lower the cyclone outlet cylinder down and use a sharpie marker to show where to trim. I hold my marker side tight to they cylinder to make the line about 1/8" oversized. Between a good pair of tin snips and lots of marks and cuts (some on me), I ended up with a nice hole that is 1/8" oversized. I got from an auto parts store some flexible rubber door edge guard (comes in a roll) material that slips on and then seals tight. It gives enough room to work that cylinder in and out, and a good enough seal as the critical seal is where the air is moving fastest. That's on the perimeter on that outer cylinder.

7. In terms of how critical that fit is, two of the industrial units we checked out had more than 1/4" gaps between the sides of the air ramp and outer cylinder. It will work any which way, but maximum efficiency requires a nice clean soldered, caulked, or glued seam on that outside. In theory the airflow on the inside is so low and small, it should not be an issue.

8. Here is an interesting picture looking up into the cyclone from the bottom that shows what the air ramp looks like installed. Thanks Red Dwyer for the picture!

1. Flux the mating surfaces of the joint.

2. Form the dust chute around the 6” template. I use one 3/4” wooden template and actually make my 6” cones so they taper from 6 1/8” on top to 5 7/8” on the bottom so the flex hose and ducting slides on easier and stays tighter.

3. Use a worm drive clamp to pull that metal tight and work the metal until you have a nice smooth joint.

4. Solder both ends of the joint then tap out the wooden disc out the larger top side..

5. Put heavy metal clams over the soldered ends to keep the joint from popping open and solder the center section.

6. Spread the tabs on the bottom of the cone just a little outward to make a nice cylinder that will solder onto the inside of the dust chute then apply flux. Alternatively, put on the flux and use a jig to pull that ring tightly onto the cone. I made my jig from a large circle that goes on the top of the cone and a smaller circle that goes on top of the dust chute ring. A long threaded rod connects the two and I tighten a nut to pull the dust chute ring wider end down tightly onto the cone. This makes for a near perfect looking joint with no tabs.

7. Solder onto the bottom of the cone.

8. Remove the 6" disks from the bottom of the cone and the dust chute.

9. Remove the screw and fill the holes with solder. 

10. Although this above procedure works like a champ, I found a little different approach that worked well for me. Instead of cutting tabs on either the cone or the dust chute, I put my cone on a heavy piece of metal (anvil) and lightly pounded just around the bottom 3/8" (some tell me it is lots easier to do before soldering up the cone, but I did it after). This expanded the metal just a little, enough so I got a good tight joint with the already soldered dust chute cylinder. I flipped the cone upside down. Tinned both pieces before making the cone or cylinder. Then put on an extra coat of flux as a lubricant. Lightly tapping the dust chute onto the cylinder, made a good tight fit. Some deep throated C clamps held all together while I soldered all in place. The results look almost like a single piece of metal!

The heavy steel plate that bolts onto the motor is key to holding the blower and cyclone. It gets mounted permanently, preferably with shock mounts so we can later remove the cyclone and blower without having to ever again lift the heavy motor and impeller. There are many ways to mount this plate and a number of different options for adding some vibration dampening. You can attach a heavy metal frame to the wall or ceiling. You can make a wooden cage, etc. I’ve even seen successful mounts using four pieces of chain attached to the ceiling then to vibration dampers or springs and then to the motor plate. Make sure you use a substantial mount because it will need to carry the weight of everything.

First Check and Prepare the Motor Plate

I now use a round steel motor plate that is 1/8" thick and 1.0" wider than the diameter of my impeller. It sits in my 3/4” thick plywood or MDF blower top. The blower top has a hole sized 1/8” larger than the impeller to let the blower shroud slip off the impeller without having to take down the motor and impeller. I made a lip to hold that metal plate tightly by routing a rabbet all around that hole. Ideally the depth of that groove I set to be the compressed thickness of my foam plus the thickness of my metal plate. The result would have the top of the motor plate flush with the top of the blower housing. This worked fine for my Delta, Leeson, and Baldor motors, but for a couple of others including my Harbor Freight motor did not work because the shaft lengths were too short. It is safer and easier on the motor to mount the impeller closer to the motor, so I had to recess that metal plate with a deeper groove. If the groove leaves less than 1/4” of material, then a metal ring should be placed on the inside of the blower top to support that plate so it can hold the weight of the motor, blower, and cyclone. Depending upon the length of the motor shaft and your choice of motor, you may have to recess your metal motor plate into your blower top to properly mount your impeller.

Test the Motor Plate Sizing

The motor plate will be held to the blower top by sitting on a piece of insulation then held tight by bolts holding large (fender) washers that screw into T-Nuts that press into the bottom of the blower top. I used a CNC router made blower top and foolishly made the hole exactly the same size as my CNC cut metal motor mounting plate. To make my unit fit I had to lightly sand the blower top and bevel the edge of the motor plate. Make sure you have a good tight fit but don’t yet mount the motor plate to the motor or blower top.

Mount the Cyclone Supports

My current personal cyclone is supported by a couple of heavy metal frame shelf brackets that indirectly attach to the motor plate. I used the large triangle shaped Stanley heavy metal shelf brackets available from the box stores. I mounted mine upside down to the wall each with three lag bolts to studs 16” on center. Putting them upside down moved the welded in support out of the way to each side of the motor instead of interfering with the blower. Before mounting I drilled four holes in my motor plate equally spaced around the motor with matching holes in my shelf mounts. This lets me use two pieces of 20” long angle iron bolted to the motor plate to rest on the shelf brackets. Instead of resting directly, to minimize vibration transferred to the wall, I instead inserted four soft rubber or neoprene shock mounts that sit between the angle iron and shelf bracket. Although you could spend a small fortune on shock mounts and I did for my first couple of cyclones, it turns out that a trip to a local automotive supply store found four soft neoprene cylinders each with 1/4-20 threaded shaft that sticks out the top and bottom. Mine were made to support a 150 pound transmission. I paid about a dollar each. Remember each only needs to support one fourth of the weight, so their total capacity should be the total weight of your motor, blower, and cyclone. With my soldered cyclone the total weight was about 150 pounds total so finding dampeners each designed to hold between thirty and forty pounds worked out well as each individual shock mount should have a capacity of about one quarter that total weight.

For my earlier cyclones I used a few other mounting approaches to provide some vibration dampening. One of the better approaches other than commercially made shock mounts was using U shaped brackets interlocked with these same kinds of cylindrical shock mounts. Here is a sketch showing how the U right side up and another upside down capture that shock mount cylinder with the screws in the end. Anyhow the U's mount to the ceiling in my shop via a square bar connected to rods or chains. I also showed how to directly mount the motor to a box that you can mount to a wall.

Mount the Motor and Impeller

With the motor mounting plate fixed firmly in place, put the motor on top and bolted it into place with star washers and the non-hardening Lock-Tite. All bolts that hold the blower and mounts require lock washers and preferably the non-hardening Lock-Tite to ensure nothing slips into the moving blower. Then mount the impeller using either a compression arbor, or special impeller star tipped setscrews with the same non-hardening Lock-Tite to secure the impeller. Make sure the impeller rotates freely and has the required clearances (Detailed instructions are on my airfoil and budget blower pages).

Mount the Cyclone Outlet Cylinder to the Cyclone Top Rings

I used a square and simply screwed the outlet cylinder to the inside of the lower cyclone top ring. A bead of polyurethane caulk around the lower seam sealed all well in place. I made sure this cylinder easily slips into the cyclone upper cylinder without hanging up on the air ramp. My air ramp has a piece of slotted rubber that runs around the inside to make a little better seal, but only the outer portion of the air ramp needs a really good smooth seal.

Mount the Cyclone Rings to the Blower

I counter sunk six equally spaced holes on the inside of that bottom blower piece for tapered 1/4"-20 screws. These attach again with the non-hardening Lock-Tite going into T-Nuts to hold those rings and cyclone outlet to the blower. The way I mounted my blower is pretty simple.

Mount the Blower to the Motor Plate

I used a thin piece of insulation on the routed area on top of the blower. That insulation goes both on the top and a little on the side, to make for a tight seal both on the bottom and edge of the blower plate. I glued a strip onto the top of my wood that when the plate is installed is just a little proud of the surface of the top of the blower. Bolt down through the blower top using fender washers, lock washers, and Lock-Tite to secure the blower top to the motor plate.

Mount the Cyclone to the Blower

Gently slide the cyclone over the outlet and onto the top rings. I made a board that wedges under the cyclone to hold it in place as I go around and put a screw every two inches. I found no need to seal this joint as it ends up near airtight after using these same rings as templates. I suppose a thin piece of rubber or felt could be used between the wooden disks if you are concerned about leakage, but there should be almost none.