Table of Contents(click on topic to go there)
- Design Information
- Basic Information
- Cyclone Building
- Static Electricity
- Noise Control
Clear Vue Cyclones is the only firm I license to build my cyclone design, blower design, and impeller designs. They have long provided completed cyclones to those who just want a system they can quickly install, plus they provide all of the individual parts for those who want to build their own. Most who build their own cyclones purchase the Leeson 5 hp compressor motor and material handling impeller from Clear Vue Cyclones.
Wynn Environmental Dick & Rick have the best pricing and service in providing excellent affordable cartridge filters for cyclones, cartridge filter upgrades for dust collectors, excellent and affordable fine dust air cleaners, 3.5", 4", 5" and 6" clear flex hose in 25' lengths and clamps. They are my recommended source for your large and small dust collection filters in both washable poly and the less expensive blended cartridge filters. They also offer the finer "Nano" filters I prefer and use myself to take better care of my poor lungs.
The Electric Motor Warehouse Barry also provides the top quality Leeson compressor motor that I recommend using with the Clear Vue 15" and 16" material movement impellers. Barry had by far the best service and prices any of us could find on the net when I started this effort and needed a good motor for small shop woodworkers. He also on request would mount the bell housing and wire for the proper rotation!
Camfil Farr and Donaldson Torit are the two most respected names in commercial dust collection. Both provide conventional dust collection systems plus they also provide fine dust collection systems for customers who must pass stringent air quality inspections. It is well worth your trouble to spend some time on both of these vendor’s web pages looking over dust collection and filtering. I used to include the Farr table that showed most stationary woodworking machines found in small shops need about 1000 cubic feet per minute (CFM) airflow for good fine dust collection. Farr also provided the airflows for larger machines such as a CNC wood router needing at least 2500 CFM air volume with 6000 to 7000 feet per minute (FPM) air speed. Farr also has some good information on filters at http://www.farrapc.com/products/hemipleat//.. This site also has a great mini video clip of what happens during pulse jet cleaning. Both Donaldson Torit and Farr are clear that when venting outside a 30-micron filter is ample, but when venting inside we need to use filters that provide at least 99.9% filtering on all particles sized 0.5-microns and larger. ASHRAE says all filters that vent indoors must be measured when clean and new. Additionally, both firms are clear that indoor filters are so fine that they will quickly clog and kill the airflow needed for good fine dust collection unless we use at least one square foot of filter area for every two CFM airflow. Sadly, every major name brand hobbyist dust collector and cyclone messes up badly on filter fineness and sizing. Most provide one square foot of filter for every 10 CFM of airflow and provide filters that can take a year or more before they build up enough fine dust trapped in the filter pores that they provide the advertized 1-micron filtering. Meanwhile we breathe in that fine unhealthiest dust.
- American Fabric Filters has some of the best add on filter bags available and will custom make a bag if needed.
Just about anybody can make a fairly good cyclone "chip collection" separator. I've seen these made of stacked barrels and all kinds of other things. To make a fine dust collection cyclone you need to get into cyclone engineering, physics and airflow dynamics. Even with thirty one years teaching college engineering plus work experience in aerospace, air and medical engineering, I found myself having to learn considerable engineering to even understand many of the articles. Searching Google for Cyclone Design led me to some of the early work done by the Cotton Institute who appears to be one of the first to seriously study cyclone design for agricultural use. These cyclones are engineered to drop the heavier dirt, sand and debris while sending the cotton out the cyclone top. Those articles recommend some major improvements to the traditional agricultural cyclone designs. I then found a spreadsheet that compared the various cyclone designs for different size and weight material. That research led me to learn that a cyclone is a special case of a swirl tube. The swirl tube information will take you into the physics behind centripetal tube separators of which a cyclone is a special case. One of the important considerations of cyclones over swirl tube is the cone design. Too short of a cone will cause the internal tornado within a cyclone to suck the material out of the dust bin. Too long and the air reversal holds the material up and causes the cone to plug. Too big of an opening coupled with a bad cone length ends up causing the internal tornado to precess meaning spin around where it sucks the fine dust off the cyclone walls. All of this research greatly increased my knowledge, but rapidly led me to realize that with the range of materials that must be separated for woodworking, that none of the traditional cyclone designs would work well for both larger chips and fine dust. From there you need to look into boundary layer and laminar air flow over various surfaces as without this you are going to pull the fine dust right off the cyclone walls and get poor overall separation. Now add in techniques to use a directed air stream to move the dust without stirring the previously collected fine dust in the collection bin back airborne. With all that you should then be ready to start engineering your own cyclone design. Cyclone Calculator gives more formulas and engineering calculations for optimizing a cyclone than you probably ever wanted to know.
Bill's "Dust Collection Basics" is my best shot at providing the overview information you need to make sense of dust collection and its technology.
Rick Peters' book is a solid collection of good information on "chip collection": "Controlling Dust in the Workshop" is one of the best, but some of the material is becoming dated such as the grounding discussion and some of the duct sizing.
Sandor Nagyszalanczy's book "Woodshop Dust Control" is also an excellent source of information on "chip collection" and a little more current than Rick Peters' book. It also focuses on "chip collection" instead of fine dust collection, plus inappropriately tries to downscale commercial ducting designs for hobbyist use. I also strongly recommend reading some of Taunton Press articles and books on dust collection. I've found them to be a great resource. Be aware that this field is changing and evolving so quickly, none are really able to keep up!
All including those who have upgraded from other vendor cyclones cannot believe how well these cyclones work. I published my initial cyclone design in 2000 and since then many thousand small shop owners have built their cyclones from my plans. Unlike all other traditional cyclones on the market, my cyclone is not a modified agricultural gravity based design. These traditional cyclones were engineered to separate off the heavy material then blow the airborne dust away outside. They were never designed to work with fine filters because they pass too much fine airborne dust. Many who work with MDF know that hobbyist cyclone designs fail miserably because with close to 100% of the fine dust going into the filters, they create a constant filter cleaning nightmare that quickly ruins these expensive filters. My design minimizes internal turbulence then uses a directed airflow to separates off almost all the dust including the fine dust. At least three MDF firms have changed over to my cyclone design. They consistently get almost no dust going into their filters. Instead of having to replace filters quarterly their same filters now last many years. Thousands have built their cyclones from my plans and even more thousands bought built cyclones of my design. Although there are some negative comments on the Internet from disgruntled vendors and a few prior firms I had to dismiss for their failure to perform, overall feedback on how well this cyclone works and how easy they are to build from my plans remains very positive.
Steve Silca was one of the early and brave who spent lots of time with me working through concerns.
Garrett Lambert Article on Building and Installing a Bill Pentz Cyclone on WoodCentral
Wayne Davey shows his cyclone project
Marco Denicolai shows his version
Stu in Tokyo shows his version
Stephen Saville shows his vacuum cyclones
Dr. Rod Cole has some excellent additional information on why we don't need to worry about grounding PVC on his site: Dr. Rod Cole on Grounding PVC (Click here).
Here are a few more sites that speak more to the hazards of wood dust.
National Institute of Heath - Wood Dust a Carcinogen
Bill's updated Wood Toxicity Table
Austrialian Wood Toxicity Table
OSHA Wood Dust Hazards
Australian Safetyline Institute - CONTROLLING WOOD DUST HAZARDS AT WORK
EPA PM 2.5 Objectives & History (fine particle research): http://www.epa.gov/region4/sesd/pm25/p2.htm
OSHA - A Guide to Protecting Workers from Woodworking Hazards: http://www.osha.gov/Publications/osha3157.pdf
Indoor Fungi (another problem with wood dust): http://www.sporometrics.com/Thesis/Chapter%201.htm
CDC - 1988 OSHA PEL Project Documentation