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Bill Pentz
Cyclone Pages

Created: July 5, 2001
Updated: May 22, 2008

Cyclone Building Instructions

Table of Contents

Introduction

Instructions

Materials

Timing

Approach

Requirements

Tools

Supplies

Preparation Instructions

General

Cutout

Soldering 101

TechniqueOverview

Surface Preparation

Tinning

Soldering

Cutout Preparation

Wooden Templates

Metal Forming

Cone

Outer Cylinder

Intake

Outlet Cylinder

Join Cone & Outer Cylinder

Dust Chute

Air Ramp

Inlet and Blower Transitions

Final Assembly & Hanging

Motor Plate Purpose

Motor Plate Prepartion

Motor Plate Sizing

Mount Cyclone Supports

Mount Motor

Mount Outlet Cylinder

Mount Blower to Cyclone

Mount Blower to Motor Plate

Mount Cyclone to Blower

Frequently Asked Questions (FAQs)

Introduction:

Instructions:

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.

Sizing:

As discussed on the Cyclone Plan page the cyclone proportions and
sizing depends upon the weight and density of the material to be
separated, our needed airspeed, our needed collection air volume, and the
size of the blower we will use to power our cyclone. With more than a
decade of warning the air engineers went to work figuring out what was
necessary to comply with the 1989 Department of Labor, Office of Safety
and Health Administration (OSHA) air quality standard for large
woodworking facilities. Their testing found once the fine dust becomes
airborne, even powerful exhaust fans and air cleaners will not pull the
dust levels down fast enough to keep their customers from failing OSHA air
quality inspections. The air engineers learned if we want to keep our
air clean, we must collect the fine dust at each tool as it is made.
If tools are made from the ground up to totally contain all the dust, then
a good sized vacuum is plenty to provide good fine dust collection.
Unfortunately, almost no woodworking stationary tools are built from the
ground up with good fine dust containment built in. Instead, we almost all
use older tool designs that either have no dust collection built in or at
best only “chip collection” meaning collecting the same sawdust and chips
we would otherwise sweep up with a broom. The air engineers found that
most of our blades, bits and cutters can launch fine dust with air streams
of 100 miles an hour or faster, yet typical dust collection blowers rarely
move air at much faster than 40 miles per hours. As a result to collect
the fine dust at each source as it is made we must start by upgrading our
tool ports and hoods to block, contain, and deliver the fine dust for
collection. If we are not willing to do these tool hood upgrades then
there is zero chance of enough dust collection to ensure meeting the OSHA
standard. Even a large airflow will not keep our shop air safe to breathe.
They spent decades refining what we need in terms of tool hoods for each
size and type of tool and much of that information is shared on my Ducting
web pages. They also spent decades figuring out how to amply collect the
fine dust from these traditional tools that did not have good dust
collection built in. What they discovered is our larger tools which only
need about 350 CFM for good “chip collection” to keep our floors clean we
need about 800 CFM to collect enough of the fine dust at each source to
ensure passing OSHA air quality standards. Because too many exposed at the
government OSHA air quality levels still get sick, the American Conference
of Governmental Industrial Hygienists (ACGIH) recommends a five times
tougher air quality standard which requires moving about 900 CFM at our
larger tools. The medical experts have long pushed for an air quality
standard that is ten times tougher than the ACGIH standard that many
larger commercial facilities already follow. To meet the medical air
quality recommendations which are already the European Union standard and
now our EPA U.S. standard we need to move about 1000 CFM at the stationary
tools found in most small woodworking shops.

I bought the “best”
magazine rated cyclone based small shop dust collection system with vendor
designed and supplied ducting plus the upgraded vendor recommended finer
filter. The air flow and particle testing done on my shop showed that
cyclone was a fraud that in real use moved less than half the airflow the
vendor advertized and its filtering was a nightmare mess that not only
freely passed the fine invisible dust known to cause the most short and
long term health damage, this filter actually served as a dust store to
save up then blast a huge amount of this fine invisible dust into my shop
every time it was turned on.

I did considerable research gathering
all the suggestions from small shop woodworkers and the professional
cyclone researchers to try and improve the dismal performance of that
cyclone system. With considerable work and much help from my engineer and
professor friends all over the world, I published my recommended changes
to that 1963 basic cyclone design that was what all small shop vendors
including the kit plan makers were selling for indoor small shop use.
Although these improvements increased airflow by more than a third and cut
cyclone overhead dramatically, the result still worked poorly. Improving
the cyclone design helped with the airflow problem, but still put near
100% of the airborne dust into the filters. We make a huge amount of fine
dust in our woodworking and that much dust quickly clogs even huge
cartridge based filters. We had to have a cyclone that got rid of most of
that fine dust if we wanted a cyclone that would work with fine filters
for indoor use. The only reasonable way to use that basic cyclone was just
like it was designed in the early 1960s, vented outside into open filters
that freely pass the airborne dust allowing it to blow away into the
outside air. Even when vented outside and with my airflow improvements,
this cyclone design still requires at least a 3.5 hp motor to move enough
air to provide the minimum pickup needed to meet OSHA air quality
recommendations. This is pretty bad news today because this design with
my recommended improvements from my Cyclone
Modification web pages is what in 2008 every small shop vendor is now
selling with two exceptions. One exception is a squat cyclone that is
so poorly designed mess that the magazine testing rated it dead last
because it even sucks sawdust and chips out of the bin into the filter.
The other exception is my design which is what these building instructions
will help you build, or if you don’t have the time or skills, you can buy
from Clear Vue Cyclones.

Coming up with my cyclone design shared here was a considerable
challenge and to get good fine dust separation you need to follow these
plans diligently. These plans did not just appear as a blast of
inspiration, but instead came from a lifetime of experience as a design
engineer and scientist plus lots of perspiration. I started off my career
in the sixties designing solid fueled rocket engines, developed many
agricultural and medical devices then developed much of the equipment now
used to measure outdoor air quality. I also was principal engineer behind
the measurement technology and tools now used worldwide to measure vehicle
emissions. I also taught university engineering for nearly thirty years
which helped me dig into the research literature to understand separation
physics then work backward to figure the sizing and proportions to make a
cyclone that provides optimum airflow and fine wood dust separation. The
optimum sizing for a typical small shop that only uses one tool at a time
takes a cyclone diameter of about 13.5” for the upper cylinder and needs
powered by a 7.5 hp blower. Forcing the air inside a cyclone to turn in a
tight separation spiral requires lots of horsepower. If we make the
cyclone larger the air does not need to turn so tightly meaning we can
trade separation efficiency for a smaller motor but larger cyclone. The
theory shows we need at least a 22” diameter cyclone for a 1.5 hp motor,
20” for a 2 hp motor, and 18” for a 3 hp motor. Unfortunately the theory
and current cyclone engineering models were all setup to only separate off
the heavier particles and chips while freely passing the airborne dust
that so quickly clogs the fine filters we need for indoor venting. To
design my cyclone I had to develop a more efficient cyclone design. Even
with a better design in theory, it still took me over a year of building
and testing different versions to come up with my 1999 cyclone design. My
family called that growing pile of parts in my backyard Mount Cyclone.
I’ve continued to refine that design to its current from shared on my
Cyclone Plans and this web page. Medical school testing shows this design
provides five times better fine dust separation by weight than its nearest
competitor, a cyclone built from the information shared on my Cyclone
Modifications web pages.

One of my main design goals was to make a
cyclone that was scalable, meaning it could be built in smaller and larger
sizes, to permit its use all the way from shop vacuums to large industrial
complexes. Rather than try to keep up with so many different sized plans,
I instead chose to use a spreadsheet that automatically adjusts the
dimensions if you want to build a different sized cyclone. Many like to
build a 6 inch diameter cyclone with 2.25” inlet and outlet because these
work so well to separate off the junk to keep our vacuum cleaner filters
from plugging.

The below spreadsheet plan is my default optimized
to provide the best possible woodworking fine dust separation efficiency
in a cyclone that will just fit under an 8 foot tall ceiling, while
delivering the 1000 CFM airflow needed for good fine dust collection at
one lager stationary tool located anywhere within a one, two or three-car
garage sized shop. This is the default spreadsheet sizing setup to build
this standard 18” diameter cyclone of my design powered preferably by a 5
hp motor turning a 16” diameter impeller.

Materials:

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.

Timing:

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.

Approach:

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..

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.

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.

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.

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:

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.

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.

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.

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.

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.

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.

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:

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.

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. .

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.

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.

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.

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.

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!

Requirements:

Tools:

Propane or Mapp gas torch, soldering tip not
required

Jigsaw, router, or band saw preferably with a circle cutting jig
for cutting out round MDF disk templates.

Electric drill

3/32" & 5/32" Drill bits

Tape measure

T-square

50" straight edge

Compass or trammel points

Hammer and metal backer block

Rubber mallet or dead blow hammer

Tin snips

Screwdriver

Protractor that opens to 9” for drawing up to 18” diameter circles

6 each 6" worm drive type 1/2" metal hose clamps (to help form and
hold cone & large cylinder during soldering)

4 each 3" worm drive type 1/2" metal hose clamps (to help form and
hold outlet cylinder during soldering)

2 each 1"+ nylon ratcheting band clamps

Pliers

VISE- Grips or clamps

Scissors

Medium metal file

Wire brush

Good heavy leather work gloves

Supplies:

If you are a touch on the perfectionist side like me 1 Pound of
solid core heavy wire solder is enough. If you are a little more
careless with more open joints then get 2 pounds of solder. The non
lead type is safest, but will not work on most of today’s galvanized
steel. Using solder that is at least 50% lead will make for much
easier soldering and better looking joints. With galvanized metal, you
should try a little solder first. There are a number of different
galvanization processes and some do not solder with normal solders.
You can buy special solder at welding supply stores designed that work
with almost all galvanized metal. (Many build their units using
pop-rivets and polyurethane or HVAC caulk. This works, but it is near
impossible for one person to get a nice smooth joint alone using
rivets unless you use some Cleco fasteners from the Air Tool Store
(see my links pages for ordering details).

An appropriate solder flux like the All-State Welding Alloys, Co.
Duzall flux (Just about any flux will work if you are soldering bare
cold rolled sheet metal, but if you are trying to solder galvanized
material you need a special flux).

4' x 10' piece of 24 gauge galvanized steel or cyclone kit (note
many want and use thicker metal, but unless you have access to a slip
roll, 22 gauge and thicker requires lots of patience and time to roll
without kinks and bends by hand!)

Flux brush or old toothbrush

At least 4 long reach Vise Grip type welding clamps with homemade
aluminum pads or 30 Each #8 pan head sheet metal screws, ½" if you are
going to use screws for fastening or soldering

10 Each 3/4" long self-starting sheet metal screws to secure the
wooden top to the cyclone body

6 1/4-20 T-nuts that will go on the bottom side of the wooden
cyclone top to hold the blower.

1 Pint lacquer thinner

Grey or red "Scotch Brite" pads

Rags

5' long piece of 6" diameter PVC or similar sized tube to help
with forming

5' long piece of 4" diameter PVC or similar sized tube to help
with forming

¾" Thick 4' x8' sheet of MDF or plywood to make the cyclone top
pieces and the template rings that will hold all nice and round when
you do your assembly.

Fine felt tip marker (Sharpie, etc.)

Wooden scrap block

12" x 18" thin rubber or vinyl sheet to be used as a blast sheet

Glue for that sheet (Barge cement, contact cement, etc.)

2 each 24" pieces of at least 1" angle iron.

Piece of 300 grit emery cloth.

Preparation Instructions

General Instructions

Always wear your heavy work gloves when handling
sheet metal including when you buy it. Sheet metal and the
staples frequently used in the metal packing boxes are razor sharp!

Shipping and handling heavy sheet metal without a few dings and bent
corners is impossible. Those dings and even some pretty significant
tears in the package are nothing to worry about unless the metal is torn
or seriously stretched. You can easily fix any bends, dents, or dings
using a hammer and backer block with light taps on your metal. You can
fix flat pieces on smooth concrete and it is best to have a curved metal
block like automotive body workers use for the curved pieces(you may
have to work both sides).

For those building their cyclones from a kit, verify your package
contains the poster board templates (6", 9", & 18" discs) and the
sheet metal for your:

Cylinder

Cone

Inlet

Inlet 6” transition

Outlet

Air ramp

Dust Chute

Practice sheet metal for soldering (kit practice pieces are each
marked with a large X)

Reduce the chances of getting cuts or metal slivers by carefully
going over all the edges both sides with your metal file.

Take the sheet metal outside and thoroughly clean
both sides with rags dampened with lacquer thinner. It generally
takes two or three passes to get it really clean enough. If you leave
the oil on the parts you can not make your solder stick, the caulking
will not stick, the glue will not hold for the interior rubber blast
plate, and paint will not stick to your cyclone.

If you bought a precut cyclone kit then skip the following cutout
instructions.

Cutout Instructions:

Important: Don’t cut the tabs until after forming! Cutting
tabs before marking or forming not only creates lots of dangerous
sharp edges, it makes the metal buckle and bend at the cut lines
making it near impossible to make nice even curves, so is bad
technique!

I used a couple of sawhorses with a 4' x 8' sheet of heavy plywood on
top covered by a heavy tarp to make my cutout work area.

Layout your metal parts following the spreadsheet dimensions using
the small cutting diagram that is on the right corner of the spreadsheet
and shown below. If you mess up at all here or are
sloppy in your cutting, the cyclone will not go together well at all.
You must be dead on with this marking and cutting!!

I used a Sharpie black marker to layout only the cut
lines. Follow with a sharp metal scribe to scratch in both my cut and
fold lines. The clear silver scratch shows up well on the back marker
lines making it easy to see exactly where to cut.

My cutting started with the little rectangular dust chute to get a
feel for working with my tin snips. I tried both aviation snips, and an
ancient pair of snips that I inherited from my father. The aviation
snips use a compound action that was lots easier on my hands, but the
older pair did not leave the burred edges from my aviation snips.

My next cut was the cyclone upper cylinder.

That cylinder got stood up on top of the cone that was still flat to
ensure an exact fit. I did the same with the dust chute ring verifying
it was the same size as the bottom of the cone. I used welding and other
magnets to hold both into that same curve. That curve is the one just
below the top of the cone, not the top of the cone!! That excess will be
bent out to form the tabs for soldering to the top.

Once I verified that I got all marked correctly I got my number one
son busy cutting away. You can cut with tin snips, a metal jig saw
blade, a power cutter, or any of a number of other devices. Using tin
snips works well for us but is hard work. Did you know that puckering up
helps with the serious concentration? It does!

After a little sweating and lots of diligent work, "we" had all the
pieces cut out. Both of us had hands so sore we needed to go rent some
videos and rest up for a couple of days!

Now that we are experts, I wonder if my wife would let me have a new
computer controlled laser cutter. We could fill in the pool and put a
roof over that area! *Wondering why my son is looking at me so funny??*

Soldering 101

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.

Technique Overview:

In a perfect world we could just put the two pieces of metal
together, apply heat and solder, and "poof" there would be a good joint.
The theory is not that hard. To get a really pristine solder joint you
need do the right preparation, and use the right soldering technique. In
terms of preparation you have to thoroughly clean the metal surfaces,
sometimes including having to remove the galvanized coating. You have to
hold the pieces tightly together. You need to slowly heat both the metal
and your fasteners all to the same critical temperature letting the
metal melt the solder, not your heat source. Then finally you need to
let it all cool totally undisturbed.

This is not a perfect world
and in practice during soldering just about everything can and will go
wrong. When melted, solder becomes very thin and runs like water or even
alcohol. It will only go into and stay in a nice clean tight joint that
is at the correct temperature. If you don’t start with new un-oxidized
solder and clean tight joints, your soldering will be a mess. To have a
nice tight joint, you can't do like a welder and just use a clamp
because a clamp will steal all the heat from the area that the clamp
pads touch. That leaves an area completely unsoldered. You can't just
let the two pieces of metal stand on their own because sheet metal
expands at different rates opening gaps between the two pieces. The very
liquid solder just pours through any extra opening. Using clamps to hold
the metal together does not work because the clamps make controlling
temperature near impossible. Tight joints require carefully forming the
metal and then securing it every 1” or closer to hold all together for
soldering.

Many find getting to that correct temperature very
difficult without getting all too hot. The right temperature depends
upon solder type, flux type, and metal, so no one temperature will work
for all soldering. With an open torch flame, bringing a small area of
metal up to the ideal temperature without overheating takes practice.
The secret is to heat slowly and let your solder tell you when you are
at the right temperature as it will flow onto metal that is just right
and you do not have to melt the solder with your torch. The solder needs
to be hot enough to flow. Heating slowly keeps you from heating past
that point where the solder and metal oxidize. Solder will not bond to
oxidized metal or solder. Overheated metal also warps making a bad joint
or even ruined piece. Once the solder or metal is overheated, you must
start over with another round of cleaning and scuffing.

In
practice, even those who do lots of soldering, find this whole process
very frustrating, wasteful of lots of solder, and creates ugly looking
joints, so they use a different process. We make our joints in a couple
of steps. We first tin each part of the joint to be soldered separately,
use fasteners to hold all together during soldering, then bring the two
parts together and gently heat a much larger area adding just a little
more solder to make a nice tight strong joint. Here's a brief overview
of this technique:

Surface Preparation:

The surfaces to be joined must be totally free of oil, grease, or
other contaminants. Take your parts outside and clean the areas to be
soldered with lacquer thinner to remove any oils or other
contaminates.

Even after a thorough cleaning, you may still have
some rolling oil or other contaminates on your metal that could
interfere with soldering. You need to start by testing your metal to
make sure it is clean enough and your solder is compatible with the
galvanizing. You make this test by just using a little flux on some
already cleaned test metal, gently heating moving your torch back and
forth around about a 3" area with a little solder touching the heated
area. Let the metal melt the solder. Do not melt the solder with your
torch or you get poor joints!

When the metal is hot enough to
melt the solder one of two things will happen. If you get a nice
smooth coat of solder with the solder spreading out easily, then you
have compatibility. Unfortunately, for most what happens is the solder
will bead, flow under the galvanizing, or oxidize badly and just plain
does not work. If your solder misbehaves, then you are going to have
to make repair. Make sure you have new shiny solder that is not
oxidized or are using the special galvanized solder. If new solder
still causes a problem, then change over to a flux designed to work
with galvanized metal such as the All State Duzall flux. If that still
does not work, use a wire brush on a drill to scratch the areas to be
joined down to bare metal or forget the soldering and consider using
rivets. A few will use an acid wash, but that is still no guarantee
for success like sanding off the galvanizing. The problem here is that
many different materials are used for galvanizing. Most use pure zinc,
but some use zinc mixed with a range of other metals that makes the
coating much tougher, but in some cases impossible to solder.

If you did not have to remove the galvanizing, lightly scuff the
joint area with either sandpaper or a Scotch Brite pad. If you have
to, then use your drill and wire brush (still outside with a mask on
as the dust is major unhealthy) to clean the galvanizing off the areas
to be joined down to bare metal. If you do this, I recommend that you
buy a spray can of cold galvanizing compound or paint your unit inside
and out to prevent rust. That bare metal will rust quickly.

Clean the just prepared areas again with lacquer thinner and bring
back inside.

Get yourself a roughly 8" square rag and make it damp with water,
but not too wet.

Get together your clamps, jig, screws, pop-rivets, or Cleco
fasteners to hold all together for soldering.

Tinning

First we learn how to tin. Use a small flux or glue brush to put a
thin coat of flux on both pieces of metal just where you want solder.

Lie the piece flat or with just a few degrees of tilt to let the
solder flow into the joint and down the joint.

Important: Making the area to be soldered near flat
and horizontal is necessary because trying to solder uphill or
at a steep angle is tough and dangerous. When liquid, solder
runs like water and can burn you badly.

Light your torch and adjust to a very low flame. If using a propane
torch, adjust the gas so the brighter blue flame project about 1/4” to
3/8” out of the torch with the tail a few inches long. Many adjust by
sound backing off the valve until they no longer here a whistle like
sound. Never tilt the torch so a stream of liquid gas runs into the
flame as that will be so hot it will buckle and quickly oxidize the
metal ruining its ability to take solder! Regardless, make sure your
torch keeps a very low flame and gently heat the metal moving back and
forth over about a 3" span while holding the solder at the center of
the area you are heating. If you overheat the metal, you may have to
prepare all over again, so take your time and move slowly. Let the
sheet metal melt the solder, not the torch flame. When the temperature
is right, the metal will melt the solder and the solder will spread
out over the heated area that is covered in flux.

For tinning, you only need the finest coat possible to just cover
the area to later be soldered. With the solder still liquid with
practice you can create a drip that you control with heat and tilting
your work to move right down the area to be tinned. For those who do
not want to work this hard, you can keep the work flat, solder an
area, then quickly wipe away the excess solder using a single stroke
with a damp rag toward the area still unsoldered. This leaves a
pristine looking smooth shiny coat of solder. If you got it too hot,
sometimes you can scrub a heated area with flux to clean it, but you
will go through a lot of brushes this way. Otherwise, to recover from
getting the solder or metal oxidized from being too hot you must clean
and prepare it again, then reapply the flux and re-tin. Always let the joint cool for at least 5 minutes before
going on to the next soldering step!

Soldering:

Once you have a good tinning coat on both pieces, put them together
and lock them in place with your fasteners. I personally like screws
if you don't have a set of Cleco fasteners.

Screws are much
easier use and remove than pop-rivets. To put in the screws I drill
out a 3/16" hole in what will be the outside of the metal every 1" all
the way down the joint. I then take whatever time it takes to ensure
the metal is so well formed that it will sit in near perfect final
position without having to use any clamps or otherwise.

I then
flux both pieces with an even coat of the Oateys or similar plumbing
flux before assembly. (In truth I've so many times gotten it all
screwed together and then realized that I forgot the flux that I
should be putting a note on the work!) Using my template disks for the
round parts, I generally put a screw opposite the side with the joint
to hold all in place, then use metal screw type hose clamps to hold
all just right. I used to use nylon band clamps but found they do not
hold as well or as tightly as the metal screw clamps and with the
metal band clamps I don’t have to screw the metal to the rings. If you
are careful in making your rings and disks, your cyclone will have
near perfect sizing, will go together easily, and makes the result
come out round instead of all weird.

I then using a wooden
backer block drill a 3/32" hole through the inner piece of metal going
right through the outer screw holes. This lets the shaft of the screw
turn in the outer piece while drawing up the inner piece nice and
tight without stripping (use a hand screw driver or you will strip
most!). I double check and if there is more than a sheet of paper
thickness of gap, out comes my small hammer and backing block or
additional screws as needed. An open joint just will not solder
cleanly.

At this point I do a little magic thanks to my
retired artist professor friend Don Heberholtz. I think my mother
(also a retired art professor) taught me that to just get something
done go get an engineer, but to learn how to really do it right go
find a good artist. Don taught me that using just the smallest amount
of that All-State flux on the joint will make all the difference in
the world. Just 1/2 oz. has been enough for me to do three cyclones
and still have a half bottle left. I think from the smell that this is
an acid, but don't know which one. Regardless, this works so well that
if I have really clean metal, the need to tin in advance vanishes!

I position the joint almost flat with just a little tilt to
let the solder run both into and down the joint. I then put on just
the least amount of the All-State flux touching its roughly 1/64" tip
opening to the edge of the joint letting just a little flow in.
followed by gently heat going back and forth about 3" of metal.

Take your torch again with low heat and warm that exposed portion
until you see the tinned solder just get shiny, then flow a tiny
amount of solder right into the joint. I let the hot metal not the
flame of my torch melt the solder. When the temperature is just right,
two things happen. First the galvanizing bubbles with the solder
flowing underneath and the solder will also flow into the joint.

If the joint is too open it will flow right through. If it is
just right the joint will "wick" in the solder to create a very smooth
curved edge of solder with no bumps or problems. That little curve of
solder if bonded correctly will make a curved surface going up from
the lower piece of metal to the edge of the upper.

I continue
to add solder to the already melted area as I use my torch to heat
down the joint. If you tinned correctly, On larger joints sometimes
you also have to solder from the inside the same way to get a good
joint all the way through, but this should not be a problem if you
used screws and nice tight joints with careful heating.

Any time I have a flow through, I know I messed up and the metal is
not pressed tightly enough together. Likewise, when I do get a blob or
problem, I take a damp rag and after heating that area with my torch,
simply wipe off that area toward where I will next be soldering, then
let it cool. After it cools, I put on new acid flux flux. The damp rag
can take away any mistakes and leave professional looking joints that
paint beautifully!

Getting the screws out is easy if you did not solder the screw
heads. Still, some of us can get a little heavy handed and bury or
coat a screw deeply with solder. In that case getting the screw out is
near impossible unless you know the right trick because solder sticks
to the screws. The easy way is to use metal clamps on either side of
the screw to provide heat sinks so the whole joint does not pop open.
Then just barely heat the screw and end of your old screwdriver. This
will take the temper out of driver. The screw will break loose before
the joint if you do this right, otherwise that screw might just have
to be ground away with a bit becoming a permanent part of your
cyclone.

I again use my All-State flux just enough to wet each hole, then
fill the holes with solder making sure you have a backer board below
the hole or the solder will run right through. Either use a metal
clamp on each side of the screw hole or work on holes well apart to
allow enough time for each to cool so you don't pop open your joint!
Don't allow the joints to reopen.

Use your rag that is only lightly damp with solvent to wipe off the
excess flux. If you somehow ended up with rosin cored solder, you will
have a muddy brown and black mess. Fortunately, you can take the piece
outside and use lots of lacquer thinner to clean that mess off.

After studying the above technique, try it on enough scrap pieces
until you get a feel for how much flux to use, how long it takes to
heat up an area, and how to flow just enough solder into the joint.

Cutout Preparation

Take your hammer and find a piece of smooth
concrete or backer steel and carefully go around each edge both sides
to flatten any bends, cut marks, or dings. Don't pound on wood as that
will leave dings!

Using your straight edge, t-square, marker, and compass, carefully
draw on the metal all of the joint, folding, and cut lines. Joint
lines are marked on the diagram with dotted lines. Folding lines are
marked with dashed lines. And, cut lines are marked with solid lines.
Be careful as these lines will show you what you need to do.

Wooden Templates

Make your wooden parts and templates accurately and clamp tightly
if you want the pieces to fit together when done. Also, the larger
donuts will become part of your cyclone:

Use scissors to cut out your kit wooden circle patterns right on
the inside line and trace the patterns onto your MDF or plywood. If
you don't have a kit, then carefully draw the patterns right on the
wood using a protractor.

<= Router Circle Jig

Carefully cutout all the wooden parts. Use of a circle-cutting jig
is preferred, but if you don't have one, then cut just outside the
line and use a belt or disk sander to make all right on. You need to
make yourself the following rings:

2 each 18" donuts for your upper cylinder and cone top to hold
them round during soldering. Be careful with the ring that will be
used to make the top of the cyclone to hold the cyclone to the
blower. I use that ring away from any area to be soldered and make
the other ring with a hole on the side that I can work through to
tack all in place. You need to put a bevel or 1/4" round over on
these rings that will be put in and out of the cyclone, or you will
never get them back into the unit after things are soldered up. You
will reach through the ring holes during the construction so round
each over a little with sandpaper to save your arms! These rings
should be drilled when clamped together with the bottom of the
blower. Make six equally spaced holes on a 12” diameter circle, and
press 1/4-20 T-Nuts into the lower ring. These holes and T-Nuts will
later permit bolting the cyclone upper rings to the blower bottom.

2 each 9" disks for your outlet cylinder to help in forming and
hold it round during soldering.

2 each just a metal thickness less than 6" disks to help with
forming and soldering the bottom of the cone and the dust chute.
This sizing is important if you want your cyclone dust outlet and
cyclone inlet to fit regular ducting. Save one of these rings as a
plug for later leak testing of your cyclone.

Metal Forming:

Important: Key to good preparation is working slowly and
gently using your fingers to form the metal without forcing it. It
takes a while, but with patience you can get it to almost fit
perfectly just as it will sit when soldered.

Form the cone:

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

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.

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

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

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

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

Clean, scuff, and put on the flux.

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

Mark the hole closest to the middle.

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.

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.

Ensure both templates and cone ends are flush.

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.

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

Sand or scrape flush.

Remove the 18" disk template.

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

Form the Outer Cylinder

Start with the cylinder on a large flat work surface (I use a couple
of sawhorses with a sheet of plywood on top covered by a thick canvas
drop cloth to keep the parts from getting scratched)

If you look closely the above pictures show what
happens if you cut the tabs before forming! If you look
closely at the picture with the hand you will see the already cut tabs.
The next picture with the bands shows how badly the cyclone outer
cylinder bent because of those tabs. The bending process starts with
those cuts and immediately creates an ugly wrinkle.

On the end of the cylinder opposite the intake cutout mark a line
3/16" from the edge that will be your guide for drilling the screw holes
needed to hold all together while you solder.

Also mark on the inside of this piece the diagonal
line that your air ramp will follow. This will make it a lot easier to
install later.

You first need to hold it together while
soldering. If you use screws, start 3/8" down from the top and
drill a 5/32" hole on that guideline then another hole every 1" down
making the last one 3/8" from the bottom.

Start forming the cylinder by gently forming a roll. Slowly work it
rolling it on a curved surface (I used a piece of 6” PVC pipe) until it
tightens up enough that it will hold its shape without having to be
clamped. I found rolling it into a tube like you would a piece of paper
works well, then just kept working that roll in the same direction on
the table tightens it up nicely. Pushing too hard will form a buckle, so
be patient. A piece of 6" PVC can also help if you have a difficult spot
or need to use your hands to work out a buckle. I clamp the PVC between
two sawhorses.

Put one of the 18" donuts on the work surface then stand the formed
cylinder on that template.

One last quick wipe of the soldering surfaces with lacquer thinner
then put on your flux on both surfaces to be joined.

Use a screw clamp to pull the bottom of the cylinder tightly onto
your template ring.

Flip it upside down and do the same with the other donut template and
a second screw clamp.

The center of the joint should pull nicely together with no big gaps
or buckles. If not, you need to go back to the forming step.

Make sure the templates and cylinder are flush at each end.

Put your wooden scrap block as a backer inside the
cylinder and drill a 3/32" hole through the 5/32" hole you marked on the
cylinder seam as the center hole and put a screw through that
hole.

Then work from the center out on each side evenly continuing to drill
and put in the screws. If you do not work from the center out, you will
get buckles and a poor solder joint.

With all the screws in support it so you have a flat joint and
carefully solder making sure you don't solder over the tops of your
screws. Use your damp rag to make the joint look professional as you go.
Let all cool for at least 5 minutes.

Loosen the screw clamps on each end and tap the rings down about 1”
then retighten the clamps. Drill and put in the final screws where the
clamps were then finish soldering this last little bit of seam on the
top and bottom.

Remove the screws, dab on solder to fill the holes moving from one
end to the other to keep from building up so much heat it pops open the
joint. Finally, sand or scrape the soldered joint flush.

Cut tabs to the 3/8" line around the intake hole and bend the tabs as
shown in the diagram.

With the lower ring still in place, cut tabs to the 3/4" line around
the bottom of the cylinder and bend the tabs straight out at 90 degrees.
Leave the wooden ring clamped in place as we will need it to hold the
shape while we bend these tabs over the cone tabs later to attach the
cone to the upper cylinder.

Form the intake:

Center a middle intake bend line over the sharp edge of your MDF or
plywood and clamp the angle iron on tight making a flush joint with the
MDF that has the metal stickiing out.

Start with your gloved fingers and lightly work all over the metal to
begin the bend.

When you have it as far as you can go by using your fingers, then
lightly tap with your rubber mallet or deadblow hammer to make a nice
sharp joint.

Repeat for each of the other side folds on the inlet adjusting as you
go to end up with the right dimensions. If you are a little long you can
make the opposite bend a little shorter - this makes a little bit of a
parallelogram but we will not tell and is needed to make the transition
and air ramp fit.

Clean then flux the mating surfaces.

Use the Vise grips and your tape measure to clamp the unit to the
right size.

Again working from the middle out drill and screw this together with
a good tight joint.

Clean, flux, and solder the center joint to make your inlet.

Now attach the inlet box to the cylinder. Bend the
tabs all inward as shown in the diagram. Use a worm
drive band clamp to firmly hold your top and bottom rings in the upper
cylinder or you will end up with a cyclone that will be warped and
unusable as it will neither fit the air ramp nor the top ring.
Slip the inlet into the cyclone putting its leading edge right to the
cylinder seam with the overlap. Hold it in place with by drilling a hole
in the upper corner through the cylinder and into the corner of the
inlet box and install a screw or pop-rivet with the head on the inside.
Then adjust the angle of the box so the box edge and the cylinder seam
are parallel. Drill and install a second screw or pop-rivet in the lower
corner, again with the head on the inside. With the box held firmly in
place, put either some metal or heavy wood inside, then gently use a
hammer to bend over the tabs on the top, bottom and side to carefully
close up any gaps. Then either clamp or drill the tabs to hold them
tightly in place during soldering.

Clean and apply flux to the areas and tabs to be soldered.

Get your inlet placed just right into the cylinder then lock it in
place with screws again working from the center out.

Solder the intake to the cylinder and the cylinder seam.

Remove the screws and fill the holes with solder.

Form the cyclone Outlet cylinder:

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

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.

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

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

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

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

Join the cyclone upper cylinder to the
cone:

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.

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

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

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

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

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

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

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.

Form and attach the air ramp

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.

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

Scruff and clean the joint areas to be soldered.

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.

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.

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.

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.

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.

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!

Form and Attach Dust Chute:

Flux the mating surfaces of the joint.

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.

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

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

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

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.

Solder onto the bottom of the cone.

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

Remove the screw and fill the holes with solder.

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!

Inlet
Transition Development:

People who make my cyclone tend to have a problem in getting
from their 6" ducting to the 4.5" x 9" cyclone inlet. We do that with a
transition. There are three ways to make an inlet transition for this
cyclone. Best is to build a custom transition, the longer the better. Next
best is to modify an HVAC 4 x 10 to 6" heating register to a 4.5 x 9 to 6"
transition. And least best is to tweak the optimum design to use a 4" by
10" inlet that just happens to be a perfect fit with a standard HVAC
heating register.

There is a fairly simple but lengthy way to
build that transition. Sheet metal workers call this an evolution. Because
my plans are scaleable, that evolution will change based on cyclone size.
I've done one by hand for a 13.5" and another for an 18" cyclone. You can
follow the below steps to build your own transition. If you would like to
learn more on making a transition and have a spreadsheet to calculate all
of the specific distances, please see Joe Emenaker's
Transition Page.

The general concept is fairly simple. By drawing a full sized
view of that fitting looking at the circular inlet you can see a circle
and the rectangle that it joins.

The more fold lines, the smoother
your circle. Most metal workers find it is easiest to divide a circle into
24 parts making for 24 fold lines then smooth the little 1/24th circle
segments to make a smoother edge on the rounded part of the transition.
Use your compass to subdivide the full sized top view drawing into 24ths.
I started by using the circle radius to divide the circle into sixths then
used compass and straight edge to divide each six into half twice ending
up with a circle divided into 24 equal pieces. If you don't know how to do
this, you should spend a little time looking this up on the Internet.
Number each point on the circle as shown. Each 1/24th will create a
straight line that will approximate the rounded end of the transition. I
used a second smaller compass that is set to this 1/24th circle length, as
it is needed constantly when doing the metal cutting layout.

Now add to that top view (looking at the transition from the
inlet) drawing the red fold lines used to transition from the circle to
the rectangle. These fold lines give us the actual length of a base of
right triangle whose height will be the length of the fitting.

The blue diagonal for each of these right triangles is the
actual length of the line used to layout the metal cutting/folding
diagram. You can either use math to calculate the lengths of these fold
lines or you can get them by drawing a right angle. I find it easier to
just build these lines with a compass but you can click
here for my excel spreadsheet that does this math for you for an 18”
cyclone. Each fold line is a right triangle with height the same as
the length of the fitting when looked at from the side. The base of each
right triangle comes from the red line length from the top view. Draw in
the blue lines. We will later use a compass or dividers to move these
diagonal fold lines to our layout. It turns out there are only seven
lengths of fold line going out from each corner. This means the first and
seventh line each end up going to two corners. Once you have the lengths
of the seven fold lines that go from each corner, you have all it takes to
layout your cutting diagram.

To draw the unfolded metal for cut out start by drawing with a
horizontal line AB that is the length of the longest side of the fitting
rectangle. Use a compass to set the length of line one. Swing arcs from
either end of that horizontal line to set the top of that triangle.

To add the next segment swing an arc that is 1/24th of the
circle diameter. Where an arc of length 2 meets that is the end point for
the second fold line. Now add another 1/24th circle arc and intersect with
diagonal length 3. Each successive line makes another triangle whose base
equals the length of a segment that is 24th of a circle.

After drawing seven lines, we next need to locate the next
corner to create the lines BA. Swing arcs that are segment 7 long from
both 7 endpoints. Intersect these with arcs from points A and B that are
equal to the size of the side inlet (4.5” for an 18” cyclone). The
intersection of these will give the new points B and A for the next two
sets of 7 fold lines. After putting in these four sets of fold lines, we
then need to draw from that final lower point to the edge of our
transition. This is a diagonal of length T or half of what we would get if
we made an arc the height of the transition.

Anyhow when it is
all said and done, the result plus 3/8" of soldering tabs gives the
transition duct. I only showed the soldering tabs for the sides. You also
need them for both the circular part and the rectangular part. I used
those extra tabs to solder a 2" slightly tapered ring onto the circular
part to mate with my PVC.

Here is a thumbnail picture you can
click on to get a full sized image of the completed inlet, plus and
interesting picture looking through the inlet into the cyclone provided by
Red Dwyer. Thanks Red!

After having helped a few friends lift and mount their cyclones, I
decided that was crazy. Picking up and trying to hold a heavy motor, blower,
and cyclone up in the air while attaching it to the wall or ceiling was way
too much work. I made my design so we start by mounting a heavy motor plate
to either the wall or ceiling. To that we add the motor and impeller. I then
mount the cyclone outlet to the lower cyclone wooden ring with screws, bolt
the blower housing to the motor plate, then the cyclone outlet and rings to
the blower housing. Finally, I slip the cyclone onto the rings and hold in
place with screws all the way around the cyclone going into the rings. Here
is an exploded diagram of the pieces:

Motor Plate

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.

Frequently Asked Questions:

Ok, so I'm an idiot, but somehow I managed to cut my cone
outlet chute on the fold line. I don't want to buy a new piece of metal.
What can I do?

There is enough material that you don't need
both sets of tabs, but since many cyclones are made with 7" and even 8"
sized dust outlet chutes there is an easier fix. Compute the width of an
8" dust chute outlet rectangle, make that part and use it to mark the
cone. Now go down 3/4" and make a cut and join as normal. The only
difference is you will now have an 8" outlet. And yes, you will have to
cut a new dust chute band, but there is plenty of extra material to make
that part. Multiply Pi * 8" then add 3/4" for the tabs for the length of
that piece.

What tips can you give me on building my own cyclone?
Many are interested in some tips. Now with hundreds having built
these units. I incorporated the tips they have shared in the above
building instructions. Here are a few reminders that are particularly
important:

Bought my first
24 gauge galvanized sheet metal at a metal surplus shop for $17 for a 4'
x 10' piece. The cost was triple at my local hardware stores and the
pieces offered were too small to make the cone in a single piece. For my
second and third metal cyclones, that shop did not have any more surplus
24-gauge metal, so I ended up buying new sheets at $28 each. I was
incredibly unhappy because the coating used on that metal would not
solder at all. I tried everything then consulted with a metal expert. He
said some coatings, particularly on galvanized metal that will be formed
instead of soldered, contain metals and special coatings that provide
extra protection but preclude soldering. I had to use swimming pool acid
and a stiff wire brush to get down to bare steel to solder these sheets.
Best to do homework before making a purchase!

For my first
cyclone when it was still in the design mode, I cut all the pieces out
of poster board at exact size without tabs. I then built it using
drafting tape (masking tape works, just a little more sticky and can
ruin the poster board). I had to do this to ensure proper fit of the
cone to the top cylinder, the inlet, the outlet, the air ramp, and the
dust chute. I then used those cutouts to efficiently lay out how I
wanted to cut the metal. I then carefully drew (scratched) onto the
metal surface all my lines adding the tabs and bending areas. As I went
I filled in those lines with a Sharpie marker to make them more visible.
I had to use lacquer thinner to take those marks off after cutting.

For my last
couple of cyclones I made my pattern out of butcher paper including
tabs, then used those cutouts to make the cutting diagram for the piece
of sheet metal. A friend gave me a full sized CAD drawing of my plans
that can be used to layout the cutting as well, but I found making
copies and handling the overhead of trying to share far more than I was
willing to do. My efforts to support a private firm to provide the parts
independently did not work out, so I am going forward at this time with
my own effort for a complete unit using specialized metal working tools
to make a low cost alternative that will take minimum work to assemble.

Start by really
cleaning the metal well. If you don't this will be a filthy job because
the metal is covered with rolling oil. To remove that rolling oil, I
found using either lacquer thinner or acetone thinner worked, but do it
in a well ventilated area.

Choose a good
way to cut your metal. Inexpensive aviation snips work well as they use
a compound joint that gives more leverage. Get either a left or right
set. They pretty much are self-correcting forcing you to cut from one
side or the other. They just don't work well at all the wrong way. I got
a set of three pair from Harbor Freight for under $10 on sale. You do
need to be a little careful as the ones I got have serrated blades that
leave marks on your cut. As a result, my son and I use a big pair of
snips that my father gave me from his early days in construction in the
forties.

Don't cut the
tab slots on the cone or upper cylinder until after the metal is formed,
or they will cause weak points that will make the metal bend in facets
instead of nice curves.

Before cutting
out the cone, cut out and stand the unsoldered cyclone top cylinder
bending it to fit onto your cone drawing. Make sure you use the line
where you will bend the tabs, not the tab line! I know, learned this one
the hard way! This will double-check the arc length of the top of the
cone for a perfect fit. Do the same check to verify all other mating
parts. The bottom dust chute must mate to the cone, etc. Use rare earth
or the bigger arrow shaped welding magnets to help hold the arc just
right as you make your checks.

Now form the
metal. I use a piece of 4" PVC pipe secured between a couple of bench
mates. With gloves on I then gently press on either side of the metal
gently using that pipe to establish a curve in the cylinders and cone.
It takes lots of time and patience, but the result looks almost as
though it was professionally rolled. I actually curl the metal a little
extra so it does not spring out later and makes things easier to work.
For the bent pieces I did pretty well by using a couple of angle irons
and clamps with a lot of fussing. My pictures above show a good working
wooden brake for bending the inlet. I made it easier on myself by
purchasing an 18" brake from Harbor Freight for $19 on sale. You really
don't need either if patient, but it does help.

Instead of using
lapped joints on the upper cylinder and the cone, one of our sheet metal
working friends suggested that instead it is much easier to simply put a
3/8" bend on each side that can be clamped together on the outside for
soldering. I tried this and it works well, but don't use that approach
because I like the "cleaner" look of nice flat joints except for that
center one at the top of the cone that needs to be big to add a little
strength. I also bought a little sheet metal seam maker, but so far the
seam maker is still theory. I see I need a lot of practice before this
unit does me any good.

Thoroughly clean
the whole cyclone with lacquer thinner again prior to getting ready to
finish forming before soldering. Lightly scuff the areas to be soldered
with emery cloth or a steel wire brush. I'm still trying to figure out a
better way and time to put on the flux, but so far it seems best to do
so just before soldering. Carefully put on lots of plumbers' flux on
just the areas to be soldered, and be careful to not wipe it off as you
put the metal together before soldering. An artist friend gave me a tiny
bottle of special tinning acid where one drop is enough to prepare a
whole joint. After securing the pieces tightly together, just before
soldering I use a little of this flux.

In general, you
need to clamp and hold all together carefully before starting to solder
using either clamps, pop rivets, screws or sheet metal holders to ensure
a tight fit. If this is your first and you don't have much soldering
experience, I prefer using sheet metal screws. Clamps are really tough
because they tend to be big heat sinks and make for lots of unsoldered
and poorly soldered areas. You will be soldering with acid core solder
and plumber's flux. Make sure your solder is a blend of real lead and
tin (anything from 50% to 70% lead will work fine), and not the all tin
used for drinking water plumbing. The 97% tin 3% copper tends to not
stick well and is much harder to use. Both plumbing and welding shops
carry the lead based solder. After, you need to remove any pop rivets or
screws and fill the holes with solder. Solder flows so freely when
melted that if you don't put a backer block of wood or something else,
it will run right through those holes! As you go, you can use a pretty
moist thick rag on the hot wet solder to take off excess and make
perfect looking joints. Afterward, a fine stainless or brass wire brush
will quickly take off the excess flux, etc.

An important key
to a good cyclone is forming round cylinders and round cone. I cheat a
little on my forming. I made a 6", two 9", and three 18" wooden disks,
all of them right on in terms of size. After putting on the flux, I slip
two big wooden disks into the cyclone top and one more into the top of
the cone to hold all dead on round and while soldering on the cone.
Without those disks, it will become oval or worse.

To pull the
metal tight to those disks I made a set of holes about 3" away on each
side then used a couple of turnbuckles and safety wire. Just a few
cranks on those round shafted turnbuckles will pull the metal top and
bottom dead on. One of my friends uses threaded rod and big fender
washers on those disks to hold them in place. Alternatively a little
drilling with a strategic screw on top, bottom and elsewhere if needed
holds all in place nicely. I've had good luck using band and strap
clamps to help hold all together as I work.

Next, I bought from
Harbor Freight 3 deep-throated welding clamps for $9 a set that work
like ViseGrips. The jaws open into a big deep square. By clamping a
couple of these jaws fairly close together I can either put in pop
rivets or just solder. I at first used the aluminum pop rivets that are
easily drilled out later, then filled the holes in with solder. A couple
of friends have written and said they liked using sheet metal screws.
Now I just kind of leap-frog those clamps right up the side soldering as
I go. The clamps are great heat sinks so the prior solder does not melt.
It takes a little fooling to get the placement figured out, but sure you
can do it! Likewise, make a similar round plug for the cone bottom dust
chute and for the transition that connects between the inlet and shop
ducting.

Thoroughly clean
the whole cyclone with lacquer thinner again prior to painting. Probably
best to not rough up the galvanized sheet metal, but instead start with
metal primer designed for galvanized followed by whatever paint you
want. Dizzy used a color similar to Jet tools that some posted as being
Krylon Ivory.

I recommend
doing careful homework before installing an oversized fan impeller. If
you do, never run a blower that has an oversized
impeller with unrestricted airflow as that can quickly burn up a
motor! Also, make sure you use a reliable amp meter at least
during the building and testing stages to ensure you are not drawing too
many amps and overstressing your motor.

I also recommend
that if you can afford it, there is considerable benefit to putting an
AC amp meter on your cyclone. It will tell you how well your cyclone is
working and when to empty filters. A Magnehelic® gauge will do the same
thing for you and give you bragging rights in terms of a pretty good
idea of CFM airflow. The correct sized gauge should be the Dwyer 2010
gauge with a 10 inches of water pressure range and the built in CFM
scale. Most of the gauges readily available on EBAY are for much larger
or smaller ranges and lack the second CFM scale. If you are lucky enough
to find one on EBAY, a 10" scaled Dwyer gauge will cost about $30 plus
you still need tubing and a pitot tube. The Dwyer 166-6 or 167-6 pitot
tubes that we need to measure hobbyist sized dust collection are near
impossible to find used and cost about $54 including shipping and
handling from Dwyer.

After years of reading on the woodworking forums that it will
take me at least 80 hours and cost me over $1200 to build your cyclone
design, many are afraid to build your cyclone. With what appears to be
hundreds already having built your cyclone, something does not make sense.
If it is really so expensive and hard to make your cyclone design, why
have so many done so? Sadly, you are getting sucked in by bad
information being given out by a few who would like you to do anything
except make a cyclone from my plans. Your cost and time estimates are
almost double what it really takes. My cyclone was engineered not to make
a profit, but instead to protect my family and me. In more than forty
years of woodworking and evolving my dust collection I made a lot of
mistakes and learned considerable eventually ending up sucking an oxygen
hose. While laid up in bed bored, I chose to put my three engineering
degrees to work building a better cyclone. When back on my feet I turned
those plans into a working cyclone. My doctor talked me into sharing what
I learned and my plans. I shared out my cyclone and blower designs for
free for anyone who wanted to build a system instead of getting a patent
for my efforts and turning them into a commercial venture. Almost every
brand of hobbyist cyclone now "borrows" portions of my plans,
unfortunately all make so many compromises there are still no other
cyclones available that do a good job on the fine dust separation we need
to protect our fine filters. Regardless, after sharing quite a few chose
to build cyclones from my plans. Word spread quickly through the various
Internet woodworking forums that my cyclone worked very well. Overwhelmed
with questions and asking for help with parts suppliers, I designed some
alternatives and talked a number of vendors into helping hobbyists out
with bulk purchases to keep the costs for our motors, impellers, filters,
and flex hose low. This made these cyclones even easier to build. I went
one step further helping my son and daughter make a little extra spending
money by having a local laser cutting firm cut kits and then do the
forming to make them easier to assemble. This reduced the normal build
time from 25 to 30 hours starting from scratch by about half. I am
disabled and could not keep up with that business, so I allowed another to
take it over. It did not work out and I eventually moved on. His friends
took things badly and ever since have gone out of their way to say how
difficult it is to build one of my cyclones even with a kit. With both of
my children away at school and me unable to do this kind of work I just
let things slide thinking eventually the building would resume. I am happy
to report it is picking up and that almost all continue to be very pleased
with the very good performance of these units. As of December 2005 the
feedback is saying it costs about $650 to build a cyclone from my plans
including blower. Those who now use my cyclone design swear by it, often
having clean shop air for the first time in a lifetime of woodworking. Ed
Morgano so liked the units he and his son built that he now builds units
in clear plastic under his Clear Vue Cyclone label.

I know a few people that I much respect who strongly recommend
the cyclones they built from your plans. I want to have the peace of mind
of having really good fine dust collection in my home basement shop. I
also have a job that owns me, so the last thing I have time for is
building my own cyclone. Do you recommend the Clear Vue Cyclone? Does it
have a serious static problem as I have heard rumored on a few woodworking
forums? Will it work as well as my making your cyclone in galvanized
steel? Ed Morgano built himself a clear plastic cyclone after
building my cyclone for his son’s shop and found it worked far better than
he ever expected. He wanted a clear one to see what was going on inside.
Although this started off as a visual aid and demo unit, his sharing that
effort generated a huge amount of interest. As a soon to retire
professional machinist his work was nothing short of incredible and demand
from others to have similar clear cyclones grew rapidly. I agreed to allow
Ed to use my design and to advertise his units on my web pages. As word
got out as to how well these work and Ed pricing them at less than what
many were spending to build one of my kits, sales and interest picked up.
Ed’s involvement pushed me to go back to work and I’ve since made a number
of improvements to the basic cyclone design and blower from my web pages
to make that unit move even more air and provide even better separation
efficiency. The thing works like a champ and I highly recommend them and
Ed without reservation.

That still leaves a couple of issues. How
long will one of these last and is there a static problem. Based upon the
plastic being used, the life of these units should meet or beat the life
of the metal units that mostly fail from too much moist sand hitting on
the same spot. The plastic is resilient and does not have this problem.
After more than a year of heavy use these units are showing little wear
and still remain clear and easy to see through. Likewise, in more than a
year of use we have not heard of anyone having a static problem. Both Ed
and I take static seriously because a large discharge with a very heavy
dust load can cause an explosion. People have been saying that PVC pipe
created similar static and would also lead to explosions, but nobody has
shown this pipe to ever be a problem in hobbyist sized shops. We just do
not make enough dust at once to create potentially explosive
concentrations (See Rod Cole’s article on static electricity). Meanwhile
Ed coats each new unit with a material that minimizes static build up. You
can add more any time you want if the static becomes a concern. Meanwhile,
Ed is working with a professor versed in static discharge physics and I am
hopeful we will hear there is little risk. In my opinion as a lay person
in this area, we are far more likely to burn up our cyclones and dust
collectors when using cardboard and plastic collection bins.

What is meant by a 2D2D and 1D3D cyclone design?
Cyclones are often named based upon the ratios of their parts. A
1D3D cyclone, also referred to as a 3D, is a cyclone that has an upper
outer cylinder with a diameter of D and a cone that is three times longer
or D*3 long. Each different cyclone design has specific strengths
depending upon the ratios between their parts. The 2D2D was designed to
separate a fixed larger particle such as grain from lighter husks. It
works, has a low overall resistance, but is not particularly good at
filtering fine particles because it was built to send them right out the
top!

I understand a tighter diameter cyclone is more efficient for
separation, but the smaller the cyclone the bigger blower impeller and
motor needed to overcome the extra static pressure caused by turning air
in a tighter spiral. Could you just make a really big cyclone and cut down
that resistance and actually gain some filtering by having the airflow so
slow that the particles just drop out because the airspeed is so low it
will not keep the fine dust airborne? In theory this is not needed
because centripetal force separates off almost all the dust before it hits
the cyclone center outlet tube, so if all else in the cyclone is designed
right, there should be little or no dust in that air stream.

What
you are really talking about is building what is called a drop box. A drop
box increases the area of a duct enough that the airspeed falls off so far
the particles can no longer stay entrained (kept airborne), so they just
fall.

To build a drop box that works, you need to know the CFM
produced by your system. Many try to use trashcan separator lids (a simple
form of a drop box) and find they do not work if you have much over 500
CFM. With my blower and cyclone designs we start with about 1200 CFM
minimum through a 6" inlet with the 14" impeller with 3 hp motor. Since
FPM = CFM / area in square feet that gives us 1200 / (3*3*pi / 144) = 1200
/ .19635 = 6111 FPM. We also know that anything over about 50 FPM will
move the fine dust and keep it entrained (meaning airborne). From that
same formula FPM = CFM / area with our 1200 CFM and a desired FPM of
<50 we get area = 1200 / 50 = 24 square feet. A tube with a 24 square
foot area has a radius of (24 / Pi)^0.5 = 2.76 feet or about 32" radius
which comes out to a 64" diameter exit tube! Moreover, this still only
reduces to 50 FPM and we need less. I've computed this a few different
ways in the past and every time come up with needing a drop box that is
bigger than 5' in diameter.

Although you recommend using a 1D3D cyclone design, your plans
and kits all use a cone that is 1.64*D long. Why? A natural
reversal point is a term used in studying swirl tubes of which a cyclone
is a special case. It means that there is a natural point where the air
traveling down the inside of the cyclone will reverse direction and head
up to exit. In terms of airflow, the 3D and 1.64D cone lengths provide
natural reversal points in just the right place to keep from our cyclones
either plugging or pulling the dust out of the collection bin. These
lengths are based upon airflow, particle weight, and cyclone dimensions. I
went with a 1.64D cone length after going through the swirl tube physics
and math needed to optimize each of these factors with the shortest
natural reversal point to permit the shortest cyclone so woodworkers could
fit it under their ceiling.

I read on a web page that you simply copied an existing
agricultural cotton cyclone and there really is no such thing as a Pentz
design. Is this true, and if not, why is your design unique? You
appear to be reading the pages and forum posts of someone who years after
I finished and began sharing my cyclone design agreed to pay me a little
for the right to sell a kit cyclone and blower based upon my designs,
stole them without paying a thing, ran up bills in my name, then tried to
rationalize his theft on his web pages with a bunch of nonsense. My
cyclone design is unique and my own based upon a lot of my research and
testing. He contributed nothing but messing up the inlet against my
advice.

Without mincing any words I bought one of the highest
recommended and most expensive hobbyist cyclones and still landed in the
hospital in 1999 with dust triggered pneumonia. My lungs required me to
either fix my fine dust collection or quit woodworking. I spent a lot of
money on that cyclone and its filters, so did my best to make it work. I
needed double the airflow that it provided. No amount of changes to the
cyclone got the airflow up enough to provide good fine dust collection. I
also had no more room in my circuit breaker panel, so going to a much
bigger blower did not make sense. The Fan Laws show that to double the
airflow I had to square the horsepower, so for my larger shop would need
at least a 10 hp motor to power my existing cyclone. I could squeeze
another 240V circuit, but not the amperage to start and run a motor that
big. This left me with two choices, get a more efficient blower or get a
more efficient cyclone. I chose to do both. Lots of research and
considerable testing went into making my resulting cyclone and blower
designs far different than the typical 1D3D agricultural cyclone. I took
my airfoil blower and cyclone designs to firm of patent attorneys. Their
patent search found both combine and innovate amply that I could easily
patent them. I chose to instead share my designs here on these web pages
so other woodworkers could avoid health problems similar to mine. Here are
some of the other considerations that went into my design:

Cyclone
Blower: My testing found the fierce competition between vendors
created a world of badly underpowered hobbyist cyclones. Almost every
hobbyist cyclone used the same design, all copies to some degree of the
early Delta commercial outdoor cyclones. To use one of these very high
resistance designs in my large shop I need a 5 hp motor and much larger
impeller. Otherwise it would not move enough air to collect the finest,
unhealthiest dust as it is made.

Cyclone
Design: Guess what else? My expensive hobbyist cyclone was designed
to sit outside and beat the ever loving out of cotton to separate off
that fiber from sand and dirt. This design may work well outside, but
when downscaled and brought indoors creates problems. It separated off
all the same chips that we would get with a broom and blew all the fine
dust right through into my filters. Although the vendor could still
accurately claim it was 95% efficient in separating off the wood dust by
weight, they neglected to mention it sends close to 100% of the fine
dust right into the filters. As a result, our fine filters quickly plug
killing the airflow needed for good fine dust collection. Cleaning these
filters frequently gives us a dust bath exposing us to the fine dust we
should avoid. Cleaning these expensive filters also rapidly wears them
out.

I then went looking hard at every other cyclone and even
trashcan separator designs. None did a bit better, and most far worse
with huge losses due to very high internal turbulence that causes high
amounts of resistance. By this I mean it takes about 1 hp larger motor
to power a cyclone or trashcan separator to get the same airflow. I read
about some success using a “neutral vane” that is an extended inlet so
the incoming air does not crash into that already spinning inside the
cyclone. Adding one of these saved almost 30% of the resistance, but my
cyclone still did not separate off the fine dust and moved far too
little air for my shop. I went back to the research and found that the
neutral vane was actually a bad idea and we really needed to clean up
the airflow within the cyclone.

Recognizing that typical
hobbyist cyclone designs were not a good solution I started over going
back to the swirl tube theory and then redesigned a new cyclone that is
optimized to minimize internal turbulence to permit using the smallest
possible blower while maximizing fine dust separation. Although I
started with the 1D3D cyclone from the Cotton Site research because of
its airflow efficiency, I then redesigned the inlet, added an
appropriate helical baffle (air ramp), and redid the internals. I
designed a new rectangular inlet sized to minimize resistance while
gently laying a smooth flow of air flat onto the cyclone outer wall and
not let it touch any already moving air. I added an elongated inlet to
further stabilize the air. I changed the internal geometry of the
cyclone so the air did not have to compress at all within the cyclone. I
also came up with an optimum angle for this inlet that gets rid of most
of the fine dust. In short, all the internals on my cyclone are
different from a standard 1D3D cyclone. I also had to address the cone
length because the unit would be too tall for my 8’ shop ceiling. Coming
up with the 1.64 cone multiplier took a lot of research, modeling,
prototyping, and testing. Other vendors simply keep opening the size of
their cone outlet (dust chute) until they quit getting plugging. That
cost them almost all their fine dust separation, but they still don’t
care that customers will constantly have airflow problems and need to
buy new filters four times as often. The result of my efforts is a
cyclone that gets the same 95% of the heavy dust as other hobbyist
cyclones. It also gets 95% of the fine dust. Many tell me they rarely
get more than part of a cup of fine dust after months of use.

I bought one of your early cyclone kits and it does not have
an air ramp. Do I need one, and would it work better with one or not?
Air Ramp: Instead of using my cyclone design that had been
in used by roughly a hundred people all over the world when I licensed a
kit version, a number of quick changes were made. One of those changes was
to change the inlet from its 4.5” x 9” size to 4” x 10” so customers would
not have to make their own transitions. They could simply buy an HVAC 6”
to 4” x 10” heater vent. Rather than go through the entire design changing
all to fit with that new sized inlet, a business decision was made to only
change that one part. The result was a nightmare in terms of reducing the
efficiency of this unit by over 100%. What happened is this change created
a constriction in the inlet. I was still pretty dumb then and was
operating on some bad assumptions. I did not intuitively understand that
at the speeds and pressures of typical hobbyist dust collection, air is
more like water. It will barely compress at all and will not go around any
obstruction. One small port, ducting reduction, or obstruction is just
like cracking a water faucet. It kills airflow. In this case it really
killed the airflow. I have heard stories about testing, etc. but the
bottom line is with that change the already carefully designed air ramp
could not be forced to fit, so the kit assembler left them out and refused
to allow me to make repair. The result works, but not nearly as well as a
unit with an air ramp and proper design. Sadly, all who got those early
kits are stuck with so much work to make repair that it is not worth
doing. Still, if you are starting from scratch or a current kit, then you
should include the air ramp. Using the air ramp saves roughly a half
horsepower and will roughly double your filter life by greatly increasing
fine dust separation.

What are the pro's and cons of the 2D2D Vs the 1D3D and 1.64D
setups? Both the 2D2D and 1D3D cyclones were designed to separate
agricultural products. The 2D2D primarily separates off grain from husks
by blowing the husks out the top. It does the same with most sawdust and
shavings, so is not a very good woodworking cyclone because all lands in
the filters. Likewise, the 1D3D was designed to separate cotton fiber from
dirt and sand. The finest, unhealthiest dust is lighter than cotton fiber,
so it passes right though this type of cyclone. The 1.64 times D cone
multiplier is a change I made to the 1D3D so a cyclone of the appropriate
diameter would still fit under an 8’ roof.

I have the 2 hp Delta motor and a Sheldon's Engineering #1225
airfoil on order. Have you come up with a design to mount the motor/blower
assembly to shock mounts on the ceiling that also allows access to the
blower for periodic cleaning? You are double lucky as neither these
motors nor that impeller are still available. And yes, to both questions.
To mount the motor I bought some strap metal and formed a total of eight U
shaped pieces. I mounted four, one in each corner of the motor board base
with the curved side up (see picture below). In the center of each I put
in a neoprene shock mount cylinder that had a bolt coming out each end. By
taking another U, turning it upside down and twisting it 90 degrees I was
able to "capture" that shock mount and mount the second U to my mounts
that attach to my ceiling joists. I used T nuts in the blower housing that
I bolted through the motor board base to hold on the blower shroud.

You say you mounted the 1 1/2 hp Delta motor and impeller on
end. Will this result in burning out the bearings someday? The
mounting vertical is only a problem if you have a motor without
permanently sealed bearings. In the case of the Delta 2 hp I'm using or
other motors with sealed bearings that is no problem at all.

You know that all of your joints have 3/8" overlap on each
side? This makes for soldering areas that are a full 3/4" wide. Why would
you not just have one side overlapped 3/8"? That seems to make more sense.
You are absolutely correct. I did design my plans with a 3/8"
overlap on both sides of the upper cylinder, the outlet cylinder, and the
cone. The reason I did this is for those who don't want to mess with
overlapped joints, they can simply bend the 3/8" tabs vertical and use
those tabs to clamp each of those pieces with simple c-clamps ready for
soldering. After, they can cover the joint with shiny automotive car-door
plastic trim. If you have lapped over joints, then you can easily cut off
that extra tab or make the joint a full 3/4" wide. That wide of joint
requires the propane torch but rarely leaks solder all over the inside as
do the 3/8" joints.

I have the Harbor Freight 5 hp compressor motor with the Jet
DC-1900 14" impeller. I have two questions. First, how much clearance
should I allow for the impeller inside the blower and how big to make the
blower outlet? Second, how do I mount this to either the ceiling or the
wall? That's lots more than two questions!

The blower
height should be tall enough to give your impeller 1/2" clearance below
the impeller, the width of your impeller and at least 1/2" to 1" above the
vanes. If you are making a normal pull through cyclone give yourself 1/4"
clearance between the impeller and the jog in the outlet that gets closest
to the impeller as opposed to only 1/8" clearance if you are using an
airfoil impeller. If you are making a push through where material can
directly hit your impeller, you need to increase that clearance to 10% of
your impeller wheel width or 1", whichever is greater, to keep from
getting jams. The blower outlet needs to be anything over the area of a 5"
circle for a 2 hp or smaller blower and 6" circle for 3 to 5 hp blowers.

Here are two
different approaches to hanging the motor and blower on the same diagram.
I like the idea of hanging the motor and blower so they can stay in place
and I can independently remove the cyclone. The motor and blower are too
heavy for me to want to lift. The right side shows the configuration for a
ceiling mount and the left side shows the configuration for a wall mount.
In either case, with the Harbor Freight motor there is a roughly 3" lip
around the motor shaft that needs to be inset into your MDF or plywood,
preferably onto foam insulation to make a good seal.

Can you tell me the size of the footprint and height of the
new cyclone with the 5hp motor? The cyclone footprint is 18" in
diameter. The blower footprint is 26" square but sits up above the
cyclone, so is mostly out of the way. The filter footprint is about 13" in
diameter depending upon brand. The cyclone height depends upon which cone
configuration you use. My motor is about 12" tall, the blower 8", and the
cyclone about 54" tall (using a 1.64 cone multiplier). That totals 74"
above the dust collection bin. You need at least 4" of flex hose below the
cyclone, so with an 8' ceiling I am limited to a collection bin that is
18" tall.

Okay, I built this thing and it is too tall for my trashcan
that I planned to use. Why didn't you make this a shorter unit like the
other vendor designs? Almost all other cyclones follow one of two
designs, and both were engineered to separate and blow away the fine dust
outside while dropping the heavier sawdust and chips into a bin. These
designs use short squat cones and trade size for separation efficiency.
Their level of separation efficiency relies heavily upon the filters for
protection. I chose to go a different direction wanting to use the
smallest possible motor, with a goal of moving the same 800 CFM airflow
with only a 1.5 hp motor. I was successful, but then discovered that to
handle the overhead of my large shop I had to step up to a bigger blower
and motor. I did and was happy with the results working well without
having to build a bigger cyclone. My design moves more than the 800 CFM
airflow we need at our larger tools with a 2-hp motor driving an airfoil
or a 3-hp motor driving a 13.25" impeller. When equipped with the 14 and
15 inch impellers now being used by many and a 5 hp motor, the result is
incredible. So, to answer your question I traded some extra height for
efficiency in both power and particle collection. I found using a standard
metal 30-gallon drum lets me fit my blower, cyclone, and dust bin
comfortably under an eight foot ceiling. If you have less room that 8’,
you can use a side outlet instead of top outlet and put your blower
elsewhere instead of on top.

What would be the downside/upside of taking the motor and
impeller off the top of the cyclone and inverting it and then taking a U
of flex tubing from the top of the cyclone to the impeller to make a pull
through unit with the blower mounted on the floor? Using tight
radius or right angle bends on such an arrangement would kill your
airflow. If you kept each radius 18" or more, in theory there will be
minimum resistance from the bend. Likewise, if you go with at least a 6"
and preferably an 8" with not less than a 2-hp motor turning at least a
12" impeller, there will be very little resistance from the pipe. If
ceiling height is a problem, seriously consider making a push through unit
(sorry, but no airfoils in this mode) following the same ducting plan but
feed into the cyclone inlet with the blower connecting to your ducting.

My basement ceiling is too short to mount it to the top of the
cyclone. Can I mount my motor to the side? A few have done just as
you suggested. By mounting the Leeson motor pointing up and reversing the
direction of rotation it works well. The nicest implementation I've heard
of used a variable pulley and slave pulley to permit adjusting the RPM.
You can go up about 25% in speed without worrying about the impeller if
you use either the Clear Vue or Jet impeller.

Is there any advantage to making a push-through cyclone
instead of a pull through? In a perfect world it would make no
difference at all because the resistance is the same on either side of the
blower. Plus, with a push through you end up with material hits on your
impeller. In our real world push through does not have to overcome the
resistance of the cyclone in addition to the rest of your system ducts,
hoods, ports, etc. The result for those who use smaller blowers, the push
through will be more efficient.

I work in the sheet metal industry and wondered why you did
not design this cyclone to be 16 or 18 gauge metal? Could I make one out
of that heavy of metal? How about using stainless steel? I use 24
gauge because I can cut it with tin snips and it does not collapse. 16 or
18 gauge would be better, but don't think average woodworkers have access
to the tools needed to fold the inlet, roll the curves, or hold the
cylinders and cone together. If you have those tools, then the heavier
metal would last far longer. Likewise, so would the stainless, but again
it takes special tools to weld it as our soldering irons just will not
work.

I do woodworking as a hobby and have zero interest in either
learning how or buying enough tools to work with sheet metal. I have a
nice 5 horsepower Baldor motor and am ordering up that 14" Jet DC-1900
impeller to make a cyclone. I took your plans to a local HVAC shop and
they said they would build me a cyclone for a modest fee. The only problem
is they want to use 30 gauge metal instead of the 24 gauge you
recommended. Will that work? The 30 gauge will work, but the first
time you close all the blast gates with that big motor turning that large
impeller your cyclone may well become about 1/2" thick. You need to use
heavier metal, at least 24 gauge. Perhaps you buy a 4'x10' sheet of 24
gauge and they use their tools to build it?

Now I'm really confused. I had just made up my mind to buy the
airfoil impeller with that 2 hp motor, and suddenly you are saying to buy
a 14" Jet DC-1900 impeller and use a very inexpensive Harbor Freight 5 hp
motor. Why? I personally am using a new Baldor motor with
Cincinnati Blower powered cyclone and a new Delta 2 hp with my airfoil
powered cyclone. I was asked to come up with an equivalent solution
without the problems of the airfoil for the least cost as there are many
buying inexpensive lesser quality dust collectors that could spend about
the same amount and end up with cyclones. I know there are less expensive
impellers than the Jet, but it is top quality and one of the more quiet,
plus the cost difference for something a whole bunch less quality was
under $10. That is why I specified the Jet impeller for the inexpensive
unit. Likewise, the Harbor Freight Motor is not by any means the best
quality, but their 5 hp compressor motor sells for under $100 (on sale for
only $69), and many just can not afford to spend two or three times that
for a good quality motor. So if you have the money and patience to keep up
with the airfoil, buy that. Otherwise, buy the Jet impeller and a bigger
motor.

How does the cyclone body mount and dismount from the
blower/motor assembly? I've used two approaches to mount the
cyclone to the blower shroud. For one, I screwed the top MDF donut that
holds the cyclone to the bottom of the blower using T nuts. I had
predrilled holes all around the perimeter and just screwed the cyclone to
that donut and was done. For the second I bought four footlocker wire cam
latches. I screwed the female parts to the donut and the male parts to the
cyclone. Lifting the cyclone up and onto that cylinder then latching those
four down pulled the cyclone up nicely, but it did take a second ring with
insulation to make a good seal.

I want an airfoil impeller, but am terrible at doing
maintenance. Is there something that you could coat that impeller with
that would reduce or eliminate my having to clean it? You might be
able to get a gunsmith to coat the impeller with Teflon or find a can and
spray it yourself. That spray used to be readily available, but I have not
seen any in a while. If you really are not willing to do the upkeep, then
buy the larger motor and material movement impeller.

Is there a concern with the start-up torque of the motor
enlarging the mounting holes in the MDF or plywood blower unit top?
If you bolt that motor on tight, it is not going to move at all. I
don't see this as a problem, particularly in the heavy Baltic birch
plywood that I used under my motor and to support my other design that
uses a side instead of face mount motor. In my kits I include a 1/8” thick
steel plate for the motor mount as a better solution. It is also much
easier on your back because the motor and blower impeller stay mounted
while you separately take down the cyclone and blower housing.

Is this like the Wood Magazine plans where they cut the air
inlet flush with the upper cylinder? No, the inlet goes inside the
cyclone right to the center edge where the joint is for the outer
cylinder. This is a much more efficient way to build the inlet instead of
having to add a less efficient "neutral vane" later. The inlet sets the
angle for the air ramp and how to cut the outer cylinder.

Where does the air ramp go? The air ramp starts on the
top of the cyclone inlet and spirals down to the bottom of the inlet
making one revolution around the cyclone outlet cylinder. Unlike the below
picture that shows how I used to attach the air ramp to the outlet
cylinder, now I find that soldering the air ramp to only the cyclone
outside cylinder instead of the outlet cylinder works best. Because the
air is moving very slowly next to the outlet, this is not that important,
but a good seal on the outside is!!

Does the air ramp go right to the edge of the cyclone?
Yes, the air ramp helix goes right to the edge of the cyclone and
is soldered there to the outside cylinder. It only fits close to the
center cyclone outlet cylinder and that joint should not be soldered or
sealed so we can take our cyclone apart to clear plugs or trapped debris.

What angle does the air inlet enter the upper cylinder?
The angle is the same as the angle that the air ramp spirals down.
To understand it takes a little work. The inlet stops at the center seams
of both cylinders inside the cyclone. The air ramp makes one rotation
around the inside. If you were to flatten out the outer cylinder after
drawing in the line that the air ramp makes when touching the outer
cylinder is a diagonal of a right triangle. That triangle has a height
that is the same as the inlet and a width that is the same as the distance
round the outer cylinder. In fact, that same diagonal length is the
circumference of the air ramp outer diameter. The same is true for the
outlet cylinder as the diagonal on that cylinder sets the length of the
inner radius for the air ramp. To make all this work, the angle is the
same as you would get by just extending the diagonals. To draw the angle
you can start just below the MDF and go to the edge.

How do you position the inlet and mark the outer cylinder for
cutting? Although you can calculate the angles to cut the outer
cylinder for the inlet, I found it better to build the inlet and solder it
up. Then build the outer cylinder, but don't solder, just hold together
with either clamps or pop rivets. Put a mark on the outer cylinder where
the bottom of the MDF will sit. Now with a straight edge put the inlet up
against the outer cylinder curve and move it down until it comes out just
below where the MDF will hit. I take a flat sharp tipped piece of metal
and scribe the upper and lower cut lines. If you have a very clean inlet,
you can cut to size and solder will fill in any gaps. If you made a rough
inlet, then it is a good idea to make your cuts 3/8" inside of that line,
then make tabs that you will bend outward to solder the cyclone to the
inlet.

Does this angle matter? The closer you stay to the same
angle of the air ramp, the less resistance and the better your cyclone
will perform both in terms of needing less horsepower, and in terms of
better separation.

Does the air inlet get cut away where you have the hidden
lines on your spread sheet? No, the outer cylinder ends up being
cut, following the procedure I just described.

I'm confused about the inlet. From the drawing it looks like
it has a strange cut. Hopefully it will be explained in the building
instructions. Pictures would be good! The inlet has long been a
source of confusion. My original drawing and dimensions did not show this
as a parallelogram, but they are now corrected. The inlet is a simple box
setup as a parallelogram. By slanting the ends of this box, it makes a
nice easy seam with both the outer and inner cylinders.

I'm confused about the connection between the inlet and my 6"
ducting. Help! Pictures would be good! The complication comes from
connecting the end of the inlet, a rectangular box, to a round piece of
ducting. I finally got so many questions on how to make this transition
that if you now look above at inlet transition and it will show you in
detail how to develop your own transition in sheet metal. It takes some
work, but is not all that difficult.

I noticed that you do not have to put the motor and blower on
top of the cyclone. That would be ideal for me as I have a basement shop
that does not have enough ceiling height to mount the motor above. What
mounting configuration will give me the least tall cyclone? If you
study the cyclone plans carefully, you will se you can seal the air ramp
and create a blank space where the aid is isolated. You can take the air
out of the top of cyclone or through that blank space. Below is a picture
plus dimensioned drawing for a cyclone top with the air going out the
side.

Which motor would you recommend with the Jet 14" impeller the
Harbor Freight 5 hp or the Delta 2 hp on EBAY? The Delta 2 hp is
way too small to push a material movement impeller bigger than about 12"
unless you choke the airflow down. Adding a cyclone to your ducting will
choke the airflow down amply that the Delta 2 hp should not burn up during
normal use. I've tested my Delta 2 hp with both the Jet 14" and the Clear
Vue 14" impellers without a cyclone attached. It tried to move far too
much air and drew way too many amps with a minimal resistance test pipe.
When connected to my ducting, cyclone, and filters there was enough
resistance that it did not draw too much amperage, but was right at the
top of its maximum design range with a 3 hp motor. Knowing motor life will
be far better with about an 85% of maximum amps, I would have to further
restrict the airflow before being comfortable using that motor.
Additionally, with this motor at near maximum capacity, you are going to
push it hard spinning up this heavy impeller with lots of blade
resistance. I have measured start up amperage at well over four times
running amperage. For sure if you use the Delta with a 14” impeller, you
want to turn on your dust collector and leave it running, not start and
stop it. In short, it can be made to work for a while, but you are at risk
of shorter motor life if you use a 2 hp motor with a 14" impeller.

The Jet DC-1900 14" impeller metric sized shaft does not match the
5/8" shaft on your Harbor Freight motor or the 7/8” sized shaft on the
Delta motor. I went to a machine shop and they made up an arbor for me for
$35 because they are my friends and I've helped them out a little in the
past. Normal cost can be up to $90 for that arbor. That's why I recommend
the Clear Vue 15" material movement impeller that already comes with a top
quality compression arbor. Clear Vue can supply that impeller and the
larger 16” with compression hubs to fit 5/8, 7/8” and even the larger
1.25” sized motor shafts.

After you get the blower, cyclone,
ducting, and filters assembled, you need to measure the amperage draw on
any of these motors. If it is too much, then you need to reduce the size
of the inlet to your blower or to your cyclone a little. Always check your amperage after assembly to make sure you don't
have too much airflow that could damage your motor.

I decided not to mess with the airfoil, so bought the Jet
impeller with the 5 hp Harbor Freight motor. How do I make my HF 5HP motor
with a 5/8” shaft work with my impeller fan which is a 0.94" hole. Did you
have to deal with the same situation? Yes, I had to deal with the
same problem. I handed my impeller, motor, and $35 to my machinist. He
pulled a 5/8" keyed arbor from a drawer, welded on a back plate, used the
Jet arbor for marking, then drilled and tapped holes. He said we could
have rolled a piece of sheet metal to fill the gap, but that was not the
correct fix. I listened to him as he has been at this a long time and does
excellent work. He also gave me a little tube of lock-tite and said to be
sure to use it on the bolts and set screws.

Do I need to protect the inside of my cyclone? About
the only place on the inside that could benefit from some form of coating
is the inside of the top cylinder where the inlet air first strikes.
Apparently the entering sawdust hits this one area hard enough to cause
wear, generate heat, and release moisture. Many types of wood contain high
silica content that means you are really sandblasting that spot as well.
The combination rusts and wears through cyclones right at that impact
point. Still, most cyclones will take years of steady use depending upon
the gauge metal used. Probably the best thing to glue there would be a
piece of thin rubber such as the Rubbermaid shelving liner I used or
square of vinyl upholstery material. Many industrial cyclones end up using
either a piece of stainless or of rubber sheet there as well. I was a
little surprised to hear that the rubber sheet holds up far better and
longer than the stainless. It's true because the rubber gives. This is why
putting the vinyl bonnets on cars protects them pretty well from small
rock chips.

I’m about to build 2 of your cyclones, and have clock-wise
spinning impellers. Does it matter which direction the air circulates
around the cyclone? Should I reverse the input direction from those on
your plans so that the uptake air spin is the same as the cyclone spin? Or
is this completely irrelevant given the 16” length of the outlet tube?
The air exiting the cyclone reverses direction spinning upward at
the reversal point. The direction of spin is set by the direction of the
air as it enters the cyclone inlet. Your unit will be a bit more
efficient, roughly 0.1 hp, if the blower is already turning in the same
direction as the incoming air as it will not have to overcome that spin.
Other than this little loss in efficiency, I was unable to measure any
difference in overall air volume or airspeed. In short, your cyclone
should work just fine no mater what way your blower needs to be oriented.
I intentionally made my cyclone with an entry reversed from my plans so it
would better fit in the limited shop space available and the result still
works well.

How can I quiet my cyclone down? It sounds like a jet engine
trying to tug away my home?

If you bolt directly to your framing, most of the noise is
fairly low frequency so like a subwoofer will go all over your shop and
house if they are attached. I know as I have 12" of well-insulated
plenum between my and my teen's room. Now all I hear is the bass. All
you can do is to change over the mounting to use shock mounts so the low
frequency stuff does not make your shop and or home walls into sounding
boards. Grainger's carries them (search under vibration hanger),
but pick a set that is sized near the overall weight as heavier mounts
provide little vibration protection.

I like adding a
muffler. PSI sells one for $49 that I have heard saves about 10 dB as
well, but it only fits a 5" outlet that I think is too small. Quite a
few have made their own mufflers out of perforated pipe wrapped with
screen then with fiberglass followed by being slipped into a larger
tube. I tried making one using PVC pipe because PVC helps dampen the
noise, but found sliding the outer pipe onto the insulated inner was
difficult. For my next I used 8" snap lock pipe on a 6" perforated
center pipe covered in window screen then fiberglass insulation. With
the 8" pipe it was bear to fasten that center seam but much easier than
trying to slip that mess into a tight PVC tube. My Home Depot store had
nice tapered 8" to 6" reducers that ended up making a pretty
good-looking unit. After I went to all that work, Larry Adcock, creator
of the WoodSucker, told me it would have been easier to just use a
length of fiberglass insulated HVAC flex duct in place of the muffler as
it apparently does a better job and costs far less. I tried that and he
was right!

I've since bought a good digital dB meter. I measured
96 db with the blower just going directly into the filter through metal
duct. Adding my homemade muffler to that same setup dropped it to 88 dB.
It went down to 92 dB using PVC duct and no muffler. Using insulated
HVAC duct it went down to 87 dB with no muffler. Using insulated HVAC
duct and my own homemade muffler it went down to 82 dB. These test
results will vary considerably depending upon how you made your blower,
your choice of impeller, motor choice, any coatings or insulation you
use, and depending if you use anti-vibration mounts.

Rather than
attach my cyclone directly to my ducting metal to metal, I use a short
length of flex pipe. That keeps the metal from carrying the sound. In
spite of my advice, my personal solution involved a lot of work. I hung
the whole setup using shock mounts. I used my home-made muffler. The
spray helped about 5-10 dB and the muffler they say saved about 10 dB.
Wrapping the outlet to the muffler with pipe wrap helped more getting
rid of the sounding boards. Also going with MDF instead of my original
plywood top on my cyclone seemed to help, but I like the extra strength
of good Baltic birch plywood, so continue to use that for my blowers. I
did try spraying the cyclone outside, but that did not seem to help
much. Spraying the outside metal sides of the blower did seem to help,
but I did that before getting my dB meter, so cannot say how much. I
also tried putting the cyclone outside, but it was way too close to my
wife's study/craft room and it quickly found itself back inside.
Probably the biggest help was building a new cyclone that was far more
carefully finished so the airflow was very clean.

In spite of my
advice, my personal solution involved a lot of work. I hung the whole
setup using shock mounts. I used my home-made muffler. The spray helped
about 5-10 dB and the muffler they say saved about 10 dB. Wrapping the
outlet to the muffler with pipe wrap helped more getting rid of the
sounding boards. Also going with MDF instead of my original plywood top
on my cyclone seemed to help, but I like the extra strength of good
Baltic birch plywood, so continue to use that for my blowers. I did try
spraying the cyclone outside, but that did not seem to help much.
Spraying the outside metal sides of the blower did seem to help, but I
did that before getting my dB meter, so cannot say how much. I also
tried putting the cyclone outside, but it was way too close to my wife's
study/craft room and it quickly found itself back inside. Probably the
biggest help was building a new cyclone that was far more carefully
finished so the airflow was very clean.

I have not tried
an enclosure myself, but I know a few of the folks who have. They
consistently said it did little to no good in terms of reducing the
noise. Since those early comments, others have responded with solutions
that apparently do work. They have built enclosures with enough room to
access the cyclone using either two layers of sheetrock inside and a
third outside or sheetrock outside and a 3M construction sound deadening
board inside. They also recommended mounting the cyclone on a wall with
isolation dampers to keep the wall from being used as a sounding board.

Adding the
baffling and sound deadening materials to the outside of the cyclone
around the blower and outlet would help considerably. My only caution
would be to not use something that becomes a dust collector.

You can also use
one of the rubberized spray on compounds such as Dip-It or a plastic
based automotive undercoating (not oil or tar). If you use either, be
careful, as the odors can be terrible.

Strangely, using
PVC pipe instead of dust collector spiral pipe or thick HVAC pipe also
seems to help considerably as you don't hear nearly as much sawdust
rattling in the pipes.

Yitah R. Wu says: "With regards to cyclone noise, I work in
automotive and one product which probably be good for reducing cyclone
noise is what we call peel and stick mastic. It's usually in 8x10 sheets
and is basically a 1/16" sheet of asphalt and recycled rubber with
adhesive on it. It does a great job of both adding mass and dampening
for sound deadening of the cyclone itself. Auto parts and auto stereo
stores typically carry this material. Some brands are Evercoat Q-Pads
and Dynamat."

I see benefits in locating the cyclone in the shop and
locating the blower in the attic directly above the cyclone. This would
add a couple feet of straight pipe, but would help deal with ceiling
height limitations and possibly reduce noise in the shop. Do you see any
significant drawbacks with this? If you put your blower in the
attic, there are a few concerns.

The fire codes
in most areas require that you use metal ducting and a metal flange
through your ceiling for the inlet, and a similar metal duct and flange
for your outlet;

You will still
need to have your dust collector, collector barrel, filter, and filter
bin in your shop to make access easy;

Obviously you
will need to bring power down through the ceiling or at least a good
heavy duty switch. If you hard wire it up in the attic, you also have
inspection problems, so need a plug up there and switch down lower;

Going in the
attic is not a good setup for an airfoil blower because you need to
check and clean it regularly. Even with a nice pull down ladder to my
attic loft area, I am way too remiss to check up there often enough;
and,

You do need to
realize that in mid summer in many areas you can easily burn up a motor
it can get so hot in your attic. You might have to do as I did and put
in a thermally switched attic fan that goes to an attic vent if yours
goes up into the 130+ degree range like mine.

I take it you soldered your cyclones together?
Yes,
for my metal ones I used my propane soldering iron to solder the first one
using acid core solder and plumber's flux. I thought I would try my big
Weller gun with a spade tip for the second as the propane heat was hard to
control and warped the metal from being too hot. The Weller with the spade
tip did not work worth a darn. I bought a bigger electric American Beauty
150 watt soldering iron from EBAY and it works lots better, but not as
good as the propane torch with a soldering tip. I wish I had bought a 200
watt unit, as I seem to keep making these units. If I knew I was just
making one, I would not even consider anything but an inexpensive propane
or small butane torch. You can use that tool for lots of things, but what
do you do with a five pound soldering iron after you make your cyclone,
fix all the gutters, and solder all the joints in your HVAC system air
tight?

Hope this covers your questions.

bill

Disclaimer

The drawings, procedures and words
shared on these pages are for information only. Your actions are your
responsibility - VERIFY and CHECK information out before proceeding, and
don't attempt anything without the required skills. Although I've taken every
care to ensure what I have done and presented is safe, dust collection equipment
uses electrical components and blowers that when improperly built, used, or
maintained may cause serious injury or even death,
so USE THIS INFORMATION AT YOUR OWN RISK! At the same time, unless you as
a woodworker provide appropriate protections for the fine wood dust you make,
you put your health, the health of those close to you, and even the health of
your pets at risk. Long term exposure to fine wood dust eventually harms most
woodworkers. Please take the time to protect yourself and those close to you.
HIRE A PROFESSIONAL ENGINEER to design, specify, test, and certify
performance of any dust collection system if you have a commercial or an
industrial application, allergies, other medical problems, people working for
you, a large shop, work with hazardous materials, or are subject to regulatory
oversight. Neither I (Bill Pentz) nor any other references or links on these
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