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Welcome to the updated Cyclone and Dust Collection Research web pages.

Budget Dust Collector (under construction)

  1. Question

    Why don't you cover how to build a budget dust collector?   This page on how to build your own dust collector has been on my web pages since 2002, but I did not include a link in the menu because I felt those who are serious would do a search and find it. These pages and my efforts are directed toward helping small shop owners protect their health. I have no interest in fielding questions or helping people build dust collectors that I know are unsafe and if used improperly create the very problem that I have spent so much time and effort trying to help people avoid. A good dust collector is the best solution if you have a shop where you can put your dust collector outside and vent it outside without returning any air into your shop. If you have to put or vent your dust collector inside your shop, then building a good cyclone makes far more sense. In some cases where money is very limited, it makes good sense to start by building a dust collector blower large enough to later power a cyclone based system. It is not hard or expensive to build a really good dust collector blower that will move the air we must move if we want good fine dust collection. This page shares how to build a good dust collector.

  2. Overview

    For those who lack the money, time, or room to build a cyclone, it still makes good sense to start by building a dust collector that moves enough air to collect the fine dust needed to protect your health, has enough capacity to power your shop, and has the power to later also power a cyclone.

    You can already do this from my existing pages by starting with my budget blower then adding a filter stack. This page shows how to combine the two.

  3. Background

    Buying a cheap dust collector is not a wise move as you will eventually have to replace it because it will work poorly. Most vendors do tricks to be able to advertize very high maximum airflows. In real use the actual working airflows make up a much lower range show by either a fan table or graph of blower performance. The higher the pressure and more duct a blower must move air through the worse the performance. Resistance is measured in water column inches abbreviated W.C. This means your blower must generate enough pressure to move a column of water 4". A small one-car garage sized shop generates between 4" and 8" water column inches of pressure depending upon ducting and how dirty our filter. A medium two-car garage sized shop ranges from 6" to 10" of resistance. And a large three-car garage sized shop ranges from 8" to 12" of resistance.

    Blower technology is very mature meaning if you buy the same size and type blower from any of the main blower makers you will get near identical blower performance. Unfortunately, imported small shop blowers are mostly so poorly made that most provide far less performance, so standard blower tables tend to be a maximum for small shop dust collector and cyclone blowers.

    If you want the full 1000 CFM that all the major vendors who guarantee air quality found we need to get good fine dust collection, the fan tables show we need at least a 3 hp dust collector turning at least a 14" diameter impeller at 3450 RPM and you must use all 7" diameter ducting. If you use an oversized impeller you can get that 1000 CFM through 6" diameter ducting but need a bigger 5 hp motor. Even the best 2 hp 240 volt dust collectors only use 12" diameter impellers so will not move enough air for good fine dust collection. None of the 120 volt dust collectors move as much air as the 2 hp units. Jet and Delta offer 120 volt dust collectors that consistently test with the highest airflow, meaning around 875 CFM in real use with a 6" diameter duct. The vendor advertised maximums are about as useful as claiming that my car gets 99.9 miles per gallon because that is what the MPG gauge says when I am coasting down a steep hill. Jet builds excellent impellers and blower housings, so I recommend you either use their parts or make your own and buy your impeller from Clear Vue Cyclones. Even with this airflow, I still recommend venting outside through fairly open filters without returning the air to your shop.

    You can buy a fair dust collector for about $250, but a good one with solid motor and enough capacity to take care of an average sized shop will cost more like $800 if you put this unit outside and do not return the air to your shop. Used price runs about half of new. Most priced in the under $600 range will still be short about 1 horsepower and a couple of inches of fan diameter of what we need to power a cyclone separator.

    After going through the unworkable dust collectors, most end up eventually with a cyclone to protect their filters and get much better fine dust separation. To buy a dust collector with enough power to drive a typical hobbyist sized cyclone you really need a 3 horsepower motor driving a 14" impeller. WoodSucker and my airfoil-based cyclones are the only exceptions that I know of. This easily puts you in the $600+ range to just buy a dust collector with ample motor and impeller to later power a cyclone.

    Then, except for a couple of brands that are known for poor quality tools, you still need to add filtering. Cheap filter bags that will only filter a fraction as well as claimed will cost you at least $50 more. Good filter bags will cost at least $100. But, a good cartridge filter with far more filtering area, better filtering, and far less resistance will only cost about $85. I recommend that all who have existing bag type dust collectors replace the top bag with a good cartridge filter and the bottom bag with a heavy plastic bag (see my DC Cartridge Conversion Page.

  4. Requirements

    Start by ordering your impeller. The minimum size is 14" to move the 1000 CFM that the experts have proven is the minimum we must move at our stationary tools. Jet makes a nice replacement 14" impeller that fits their DC-1900 dust collector that you can power with a 3 hp motor, but this is not what I would order. The problem with the 14" is you need at least 7" diameter ducting to move that 1000 CFM. To move 1000 CFM through a 6" diameter duct you need a 15" or 16" diameter impeller and a real 5 hp motor. I recommend you instead order a Clear Vue 16" impeller with 5 hp Leeson motor as this will give you optimum airflow when you later add a cyclone.

    Next chase down an inexpensive motor. Ideally, a 3 hp to 5 hp 3450 RPM pump motor would be best. These are available used and rebuilt from pump and swimming pool shops for about $50 and off eBay for about $100. You can rebuild one that only needs bearings for under $30 if you have a press and know what you are doing. You can also order up a 2 hp Delta off eBay for under $100 including shipping, but these are really a little too underpowered, so often require consticting the inlet to keep the motor from drawing too many amps and overheating..

  5. Basics

    Building your own dust collector is not that difficult but there are a few basic things to understand. Dust collectors pass all the material right through the blower and so do cyclones when the dust bin gets full or cone gets plugged, so NIOSH who sets U.S. safety standards recommends both only use heavy duty steel material handling impellers that can take material hits and do not spark. Sadly we have multiple small shop vendors who still sell cyclones and a couple who sell dust collectors with aluminum impellers. At one time the thinking was a heavy aluminum impeller would be safer and not spark, but too many fires proved that aluminum when hit with a piece of metal launches little white hot sparks similar to a 4th of July sparkler (look up thermite reaction if you want to know more). These sparks cause fires. This is why NIOSH reversed their early recommendation and went back to only recommending steel material handling impellers.

    impeller Type & Material: impeller Blower technology is mature meaning it is so well understood that buying the same sized blower from each of the major blower makers results in near identical performance. The major commercial blower makers all use the same types of material handling impellers in their

    The problem with dust collector and fine filters is the same for everyone. Dust collectors work great for "chip collection" meaning collecting the same chips and sawdust that we would otherwise sweep up with a broom, but almost all do a terrible job when it comes to fine dust collect. The only way I recommend using a dust collector is exhausting the air outside. Filtering a dust collector is just not that practical. There are two major problems. First, few dust collectors move enough air to actually be effective at collecting the fine dust. Second, it is impractical to try and put a fine filter on a dust collector. Properly sizing a filter to a dust collector requires far more area than we can get with a fine filter bag. Stepping up to a cartridge filter poses problems because our dust collectors blast sharp chips which punch holes in the filter material, plus these chips lodge in the filter pleats requiring us to have to dig them out. That digging can easily ruin a filter. filter will cause that filter to need cleaned far more often. Cleaning breaks down the filters so they soon begin passing larger particles. Upgrading to a larger cartridge filter with ample area sounds like a good idea, but most cartridge setups on dust collectors work very poorly. Again most cartridge filters are too small in overall area creating a cleaning and rapid filter wear out problem. Most small shop vendors sell filters that freely pass the finest dust. This creates a dangerous false sense of security because our shops look clean while having dangerously unhealthy airborne dust levels. Additionally, fine cartridge filters do not work that well with dust collectors. Dust collectors put close to 100% of the fine dust into the filters. This means all dust collectors will quickly ruin expensive bag and cartridge filters. As dust collectors get full they blow sharp chips at a high rate of speed which will poke our filters full of large holes killing their ability to do good fine dust separation. They will also blow chips up into the filter pleats clogging the pleats again with our digging those chips out often ruining our fine expensive filters. Dust collectors provide almost zero fine dust separation. This means our filters end up with a constant high load of fine dust that keeps clogging the filters. The required cleaning will quickly wear out our expensive cartridge filters.

  6. Blower and Filter Parts

    (Shipping and full retail prices quoted, so all should be higher than your actual cost - See my Links Page for contact and ordering information):

    • $150 14" material movement impeller

    • $100 Good quality 3 hp to 5 hp 3450 RPM motor

    • $85 Wynn Environmental 300 square foot Farr compatible filter

    • $20 3/4" MDF or Baltic birch plywood for the blower top, bottom, and filter stack

    • $12 An 8" round to 8" square HVAC duct transition for blower to filters (will need cut down to fit blower 5 5/8" x 7" opening)

    • $5 An 8" connection for the filter stack

    • $15 Blower sides and hardware See Budget Blower for detailed hardware requirements

    • $10 4' x 4' Piece of fiberglass window screen

    • $10 Buy a 4' length of 8" heavy insulated HVAC flexible duct (muffler and connection to filters)

    • $407 Subtotal

    Just like with any commercial dust collector, in addition to the parts above that make the dust collector, you still need a few more items to make this system work:

    • Buy or build a good tight sealing 4" blast gate for the filter stack

    • Buy enough 4" hose to go outside your shop from that blast gate

    • Buy a 10' piece of 6" flex hose and put your unit on wheels
      Buy a longer piece of 6" hose or ducting if you put your collector in a fixed location.

  7. Assembly
    1. Now go to my budget blower page and follow the instructions there to build your own budget blower. Modify the HVAC transition to fit on the blower and attach it to the insulated 8" HVAC flex duct.

    2. Sew or use heavy fishing line to make your window screen a cylinder that will fit snugly inside the filter and put that screen in place.

    3. Build a filter stack then connect it to the HVAC flex hose coming off the blower.

    4. Now connect up the blower to either your ducting or flex hose.

    5. Finally, and most important tune your blower so it does not over-stress your motor. A motor trying to move too much air will draw too many amps, overheat and eventually die and possibly cause a fire. Tuning the motor is easy. Put a clamp on amp meter (See my testing page for sources and procedures) on one of the blower hot leads. Now open all blast gates including the gate on the filter clean out and check the motor amperage. It should read no more than about, 95% of its rated amperage. If it is lower, fine, you are done. If it is higher, then you need to systematically reduce your blower inlet until that amperage is at the 95% mark. The easy way to do this is install a blast gate just before the blower inlet. Slowly close that gate until you get the amperage desired, then firmly lock that gate in place. If it accidentally closes, nothing will get hurt as the blower draws the least power (amps) when pushing against the least air. But if it were to slip open all the way, then it could over-stress the motor.

    I've shared an approach that will quickly get a top quality blower built and stay well within what it would cost you to buy a new dust collector. I've received dozens of emails from hobbyist woodworkers who have built their own dust collectors for far less by putting more time and some careful scrounging. Here are some of the ways they greatly reduced costs:

    1. Find a large truck service depot and get four used large truck air filters, hopefully for free. Then build your cleanout and filter stack around those filters.

    2. Go to motor, swimming pool and pump shops looking for a good motor that just needs bearings. You can often get these motors for little or nothing and it only takes a few dollars to press in new bearings.

    3. Spend the money to buy a good quality steel impeller with a good solid arbor mount. Don't try to use either an airfoil impeller or an HVAC squirrel cage fan, as both would be ruined by the small blocks and pieces of hardware that inevitably get sucked up during dust collection. Both will also quickly clog, get badly out of balance, then destroy themselves and motor bearings from the strings and long shavings pulled in. Don't try and use a light aluminum or alloy impeller, as both tend to explode when hit enough times. Finally, don't use an impeller that is held on the blower shaft only with setscrews. That works fine for moving clean air in systems where the blower motor shaft is horizontal. When mounted vertically, the setscrews are not enough to keep the impeller from eventually slipping and crashing into the blower shroud.

    4. Make all the blower, filter tree, ducting and transition parts yourself.

    Now that should pretty much do it allowing you to build a pretty incredible dust collector system for under $400 and some "sweat equity".

  8. Disclaimer

    The reader assumes all responsibility and liability associated with the hazards of woodworking and dust collection. Dust collection when improperly built, implemented, used, or maintained may cause serious injury or even death, so USE THIS INFORMATION AT YOUR OWN RISK! The author has no control over how a reader will act as a result of obtaining information from these pages. Your actions are your responsibility, VERIFY and CHECK information out before proceeding, and don't attempt anything without the required skills. The author shall not be responsible for any errors or omissions that may be present on these pages. Accordingly, the author shall assume no liability for any action or inaction of a reader.

    The drawings, procedures and words shared on these pages are as in use by the author and shared for information only. No claims are expressed or implied as to the safety, usefulness, or accuracy of this information. Neither the author nor any other references or links on these pages will accept any liability for any damages or injury caused to people or property from use of this information or from any associated links.

    These pages are directed toward a hobbyist and small shop woodworker audience and are not intended for application in a commercial, institutional, or industrial setting. Commercial woodshops are generally governed by a complex set of worker safety regulations, such as those mandated by OSHA. Satisfying the compliance of such regulations is beyond the scope of these web pages. 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.

    Unless you as a woodworker provide appropriate fine dust protections, most small shop owners put your health, the health of those close to you, and even the health of your pets at risk. Unfortunately particle testing by the author and hundreds of others all across the country shows those who vent inside even with very clean looking shops invariably have huge build ups of invisible dust. Government testing shows on average just one hour inside a small shop that vents its dust collection inside results in more fine dust exposure than large facility commercial workers receive in months of full time work. The difference is almost all large commercial facilities vent their dust collection systems outside, so they rarely build up the fine invisible fugitive dust that escapes collection. Even with venting outside, the peer reviewed medical research shows the more fine dust we take in the greater the short and long term health damage and this research also shows even with their much lower exposures almost all large facility woodworkers develop serious dust triggered health problems and significant loss of respiratory capacity. This should terrify small shop and hobbyist woodworkers because of our much higher exposures. Respiratory doctors who have read these pages share small shop woodworkers and their family members often have the worst respiratory problems. Please take the time to protect yourself and those close to you.

Copyright 2000-2018, by William F. Pentz. All rights reserved.