112-dustcollection.pdf

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2/9

DUST

COLLECTION

ROUND-UP

2007 August Home Publishing Co.


3/91 www.Woodsmith.com 2007 August Home Publishing Co. All Rights Reserved.

WOODWORKING TOOLS

AND REQUIRED AIRFLOW

10" Table Saw 550

Surface Planer 550

Belt/Disk/Drum Sander 550

Compound Miter Saw

475

Router Table/Shaper 450

Band Saw 375

Scroll Saw 375

Jointer 375

Drill Press 375

f the letters, emails, and phone calls weve been receiving of lateare any indication, then concerns over dust in the woodshophave become paramount to many woodworkers. Theres little

question these days that wood dust is a very real health concernfor woodworkers. (At least three public health agencies haveclassified wood dust as a carcinogen.) And along these lines, weget a lot of inquiries about how much or how little dust control isenough. There seems to be a lot of confusion over how to compareone dust collector to another.

Of course, theres no one size fits all dust collector. Differentshops and different budgets require a variety of solutions. Ivedivided those choices into four categories, which are described indetail on the following pages. In considering each of these options,its important to weigh their costs relative to their capabilities as

well as their limitations.As to side-by-side comparisons of dust collectors, the most

telling information can be found in their performance curves.

POWER TOOL CFM

I

TIPSFROM

OURSHOP

DUSTCOLLECTION

Cyclone.Cyclones

are the best option,but not the only

option, for dust con-trol. Details of fourmore dust collection

systems begin onpage 3.


4/9

SAMPLE PERFORMANCE CURVES

2 www.Woodsmith.com 2007 August Home Publishing Co. All Rights Reserve

This graph shows representative performance curves for two populartypes of dust collectors. Notice that both collectors have a maximumairflow of approximately 1,150 CFM. As pressure increases, the CFMof each tool declines correspondingly. Also note the steeper declineof the curve for the single-stage collector.

At first glance, the dif ference in the curves seems negligible.However, if you consider at what point the collectors fall below 550CFM (the airflow typically considered minimal for collecting dust at atable saw) the difference in the machines becomes more meaningful.

The single-stage collector falls below this threshold at approximately5" of static pressure. The cyclone reaches the same point at about6" of SP. Again, an apparently insignificant difference. But considerthat a mere 1" of SP difference represents almost 15 feet of 4" duct,and the cyclones advantage is clear.

200

300

400

600

500

700

800

900

1000

1100

1200

1 2 3

Minimum for Dust Extraction

Minimum for Table Saw

CYCLONE

1" Difference in

Static Pressure

INCHES OF STATIC PRESSURE

CUBICFEETPERMIN

UTE(CFM)

SINGLE-STAGE

COLLECTOR

4 5 6 7 8 9 10

FUNDAMENTALS FOR DEFEATING DUS5

collect dust from the most popularwoodworking tools.

Keep in mind that every foot of

ductwork and every fitting increasesthe pressure that the dust collectormust overcome in order to maintainadequate airflow. So its crucial thatductwork be constructed as effi-ciently as possible.

In that vein, the sidebar at rightprovides some basic guidelines forgetting the best performance from

your dust collector. While theseguidelines are most pertinent to cen-tral systems, the principles remainthe same for collectors of all size.

These simple graphs show howthe volume of air moved by a dustcollector (indicated in Cubic Feet

per Minute or CFM) is affected byan increase in pressure, as whendrawing air through a system of duc-twork. (This is measured in Inches ofStatic Pressure, abbreviated as SP.)

The sample curves (below) showhow two systems with similar CFMratings fare quite differently as staticpressure increases. (Performancecurves for most dust collectors areavailable by request from manufac-turers.) The table on page 1 showsthe airflow required to effectively

24-ga.

MetalDuct

MetalDuct Tape

24-ga. Long

Adjustable

Clear Flex Hosewith Ground

Blast Gate

Short & Straight.The duct between th

tool and the collector should be in th

straightest possible line and as short as yo

can make it. When making turns, try to u

45 fittings instead of 90 fittings.

1

Use Dust-Worthy Duct.PVC pipe an

HVAC dust do not make good dust co

lection duct. PVC creates far too much add

tional pressure and HVAC duct is too thin

withstand the pressure of a dust collector.

2

Seal all the Joints.A small leak in th

ductwork can have a huge impact o

the efficiency of your system. All connectio

should be sealed using either metal du

tape (good) or silicone sealant (best).

3

Use Blast Gates.Blast gates ensure th

youre only drawing air through th

tool in use. Install blast gates at every to

branch and then use them.

4

Finer Filters are Better.Besides captu

ing a lot more of the harmful dust,finer filter increases the efficiency of yo

dust collector. Thats because, although th

holes in a fine filter are smaller, there a

a lot more of them. That allows air to pa

more freely through the filter, creating le

pressure for your collector to overcome.

5



Single-stage dust collectors like the one repre-sented here continue to be the most popularchoice for the home woodshop. There are a

number of reasons for this.First is the relatively low cost. Single-stage

dust collectors can be one-half to one-third thecost of similarly sized cyclone units.

Second are the very satisfactory perfor-mance characteristics. The 1-hp unit shownhere boasts 1,250 CFM (before factoring inany static pressure remember the perfor-mance curve) and 42 pounds of dust collec-tion capacity. This is more than adequate onboth counts for most home woodshops.

A couple more reasons for the popularity ofsingle-stage systems are their ease of setup

and versatility. Whether your shop consists ofa couple of stationary tools or an entire garagefull of dust-raising woodworking machines, asingle-stage collector can be configured tomanage the dust effectively in short order.

Right out of the box, most of these collec-tors have casters on their bases. So it isnt nec-essary to run an elaborate system of ductworkin order to put the collector to work. You cansimply roll the collector from tool to tool as

youre working.As an alternative, most single-stage collec-

tors come standard with a Y-connector so youcan connect more than one tool at a time. Byusing blast gates and a couple lengths of flexhose (typically not included) this can cut waydown on the number of times youll have tochange the hose from one tool to another.

There are, however, some limitationsto single-stage collectors such as this one.Some of those limitations can be remedied(seeThree Ways to Enhance Performanceonpage 4), while other frailties are just part andparcel of single-stage design.

The most limiting factor of single-stage

collectors is the fact the the impeller mustbe able to withstand the constant impact offlying debris (by definition,everythingthatgoes into the ductwork passes through theimpeller of a single-stage collector). For thisreason, efficiency takes a back seat to dura-bility in the construction of a single-stageimpeller. Which is a big part of the reasonthese collectors suffer a more rapid declinein performance when compared to two-stagecyclone collectors.

SINGLE-STAGECOLLECTOR

How it Works.In a single-stage

collector, all dust and chips passthrough the impeller. Large dust

particles and chips collect in

the lower bag and finer dustis filtered as air exhausts

through the upper bag.

Filter BagTypically ratedfor 30-micron,

much finerbags are widely

available

CollectorHousing

Collection BagCloth is standard,finer filter bagsrequire plastic

ImpellerDesigned to moveair and withstandimpact from dustand woodchips

IntakePort


6/9

SEPARATOR

CONNECT IT DIRECTLYFILTRATION


1-micronFilter Bag

4"-diameterTrunk

4" FlexHose

NOTE:Y-Fittinghas beenremoved

CanisterFilter

3"-diameterBranch

Y-Fitting

Plastic

Collection Bag

Several options are available

to improve on the 30-micronfilter bag thats standard fare on

single-stage collectors. Below is a

1-micron filter bag with a plastic

lower bag (this forces all the air

through the filter bag). At right

is a canister filter rated to trap

particles as small as .5 microns.

1

By removing the Y-fitting

(photo, below) and connect-ing the ductwork directly to the

collector, you eliminate an unnec-

essary restriction and are able to

start with a larger diameter of

duct. (Each branch of the Y is 3

in diameter. The trunk has a 4

diameter.)

The canister filter not only

captures smaller particles than a

bag, but also increases filter area

almost 600%.

2

Centrally located systems

should also include a separa-

tor (illustration, right). This effec-

tively turns a single-stage collector

into a two-stage collector, which

has a couple advantages.

First, the large chips are col-

lected in the separator before theycan impact the impeller, which

lessens damage to the impeller

and extends its useful life.

Secondly, emptying the gar-

bage can that serves as the chip

collector is much easier than

removing the lower bag from

the collector itself.

3 WAYSTOENHANCEPERFORMANCE

3


7/9

{ How it Works.Dust is drawn directly into

the garbage can, where heavy particles settle.Fine dust is captured in the canister filter.

This two-stage collector combinesspace-saving portability (provided

you use a trash can with casters on

it) with the performance of two-stagedust collection (see photo at right).

The collector fits 20-gallon steel gar-bage cans or 32- or 40-gallon plasticcans. The weight of the collector isenough to hold it firmly in placeand create a tight seal.

Large chips are collectedin the trash can (not in-cluded), and fine dustis captured in the cartridgefilter before the air is recircu-lated into the shop (seeHow it

Works, at left).You might think that the

small filter will require con-stant cleaning, but that isntthe case. The efficiency of two-stagedust collection, and the surprisinglylarge filter area inside the cartridge

{ How it Works.Both heavy chips and finedust are drawn directly through the impeller.

A single bag functions as both chip collectorand dust filter on units such as this.

as often, but dont count on this unitto maintain a safe level of air quality.

The bag shown here is rated for 1-micron, which is finer than the bagsof most similarly sized units. But evenat this level, airborne dust escapingthrough the bag is a real concern.

Because these units are designedto be compact, impeller size is re-stricted compared to the largermodels. The result is a steeper de-

cline in the performance curveas pressure is increased. Forthat reason, these collectorsare intended to be connect-ed directly to a single tool.

The size of the bag alsolimits the usefulness of this

collector. A planer or jointer willfill the bag too quickly to make

the unit particularly useful. None-theless, for under $200, these units dohave their place in the small shop.

TWO-STAGECOLLECTOR

COMPACTPORTABLE


This is the most affordable type ofdust collector available. Not surpris-ingly, its effectiveness is limited.In fact, this type of collector offersmore in the way of convenience thanit does in effective dust collection.

You wont have to sweep your shop

mean youll only need to clean thfilter after every third or fourth tim

you empty the trash can.

The one drawback to this unithaving to lift the heavy, awkwacollector off of the trash can eatime you empty it.

Impeller

IntakePort

Motor

ExhaustPort

ChipDeflector

CanisterFilter

CleanAir

HeavyChips

MotorFan

Housing

Impeller

IntakePort

Roll-ArounTube Fram



Cyclone dust collectors are inargu-ably the best dust collection system

you can install in your shop. Theirsuperior performance and their namecome from the cyclonic action illus-trated inHow it Workson page 8.

The efficient separation of dustfrom air means the impeller in a

cyclone collector can be designed togenerate maximum airflow withoutconsideration for sustaining impactfrom flying wood chips. This givescyclones a much better performancecurve and makes them highly effec-tive even when connected to an elab-orate system of ductwork.

Filtration can vary between manu-facturers. The Oneida shown hereuses a pleated cartridge filter that

captures 99.9% of dust particles downto .2 microns.

Clearly there is no need and nomeans to improve the performanceof a cyclone collector with add-ons.

You can, however, choose betweenan internal filter (see page 8) or anexternal filter (see photo above and

illustration on page 8).There is l ittle in the way of per-

formance difference between thesetwo options.The real differences arespace utilization (the external filtertakes up a lot of room) and conve-nience (cleaning the internal filtermeans taking the cyclone apart see Oneidas tip for easy reassemblyin the box on page 8). Cleaning theexternal filter calls for blowing the

pleats clean with an air hose andemptying the dust pan.

The cost of a cyclone, and themisperception that they must beused with a fully-plumbed systemof ductwork, often lead home shopusers to consider less costly (and lesseffective) means of dust control.

Contrary to popular belief, cyclonecollectors do not have to be con-nected to a complete system of duc-twork to be useful. An economical

way to get started with a cyclone isto mount the unit on a mobile stand(available from Oneida) and use it

just as you would a portable single-stage collector. As budget allows,

you can add ductwork and blast gatesa little at a time.

CYCLONETWO-STAGEWITHATWIST

{ Although often configured as a central

system, as shown here, cyclones canbe used as portable systems.


9/9

CLEANING AND REPLACING

INTERNAL CYCLONE FILTER

To save space, Oneida cyclones can be configured withan internal filter. The trade-off is that you must removethe metal cone of the cyclone to access and clean the

filter. The real trick, though, is getting the cone backon. Oneida offers this advice.

Internal FilterRemoval.

Disconnect the conand move it aside

while you removethe internal filter fo

cleaning (Fig. 1).Once removed, blo

the pleated filter clewith compressed ai

{ Using Suction to Connect.To reattach the cone aft

installing the clean filter, first make sure all of the blasgates are closed. Then turn the cyclone on and let the

suction draw the cone tight against the barrel (Fig. 2)The suction will hold the cone tight against the bottomof the barrel and allow you to use both hands to re-

attach the snap ring (Fig. 3).

{ How It Works.Debris enters the barrel and is sepa-rated in a cyclonic stream of air. Large dust particles

and chips fall into the bin and finer dust is trapped inthe cartridge filter.

NOTE: Some informationpresented in this

illustration is specificto Oneida Cyclones

and may not representproducts from

other manufacturers.

Motor

ImpellerDesigned to

create maximumairflow

BarrelandCone

Combine to createcyclonic air streamwhich removes 99%of dust from the air

MountingBracket

IntakePort

ExhaustPort

Chip Bin35- or 55-gallon sizes,

easily removablefor emptying

Fine Dust BinRemoves easilyfor emptying

Flex CouplingExpands or contracts

so cyclone will fit undermost ceiling heights

CartridgeFilter

Captures 99.9%of particles from0.2 - 2.0 microns

BaffleReduces

noisefrom

exhaust

SnapRing

1

2

3

112-dustcollection.pdf

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