Some Info Straight From Bill Pentz

  • Advertise with us
Blog entry by ToddE posted 08-28-2007 03:06 PM 14820 reads 1 time favorited 4 comments Add to Favorites Watch

I wanted to share some comments Bill Pentz had for me when I asked him about my new 2 HP cyclone purchase. So…here goes…by the way, Bill spends hours a day answering emails, like 7 hours a day. I hope that you would take the time and read the information he has on his web site ( and the comments below before you would write to him. I pretty much asked him the plain facts, so this should take care of any discussion questions you may want to ask him. Also, I put his recommendations for my other four questions at the bottom along with the question I asked. (By the way, if I did what he wanted me to do in the first sentence, I would be closing my shop because my wife would kill me after I just bought this thing and set it up!) Enjoy. Todd

In short, send that cyclone back and either buy or build a cyclone of my design and equip it to blow outside during nice weather and into a pair of the Wynn 300 square foot filters during bad weather.

With all that said there virtually zero chance that your cyclone is going to do anything more than give a false sense of security from making your shop look clean while it loads up with an ever increasing amount of the finest unhealthiest dust. I was right where you are nine years ago and my top magazine rated cyclone ended up building up so much fugitive fine invisible dust that my immaculate looking shop tested with more than twice the OSHA maximum after three months with no woodworking from just turning on my cyclone. I lost 68% of my lung function and am still required to stay on oxygen at night. I was blindsided by the false sense of security from the advertising claims which had nothing to do with the reality. The reality is fine invisible dust, particularly some of the nicer hardwoods, lingers in even the cleanest looking shops for years. Every time you go into a shop with this kind of dust, your body becomes a little more allergic. Eventually, you get sick, often with symptoms of a cold or flu that takes a long time to shake. That may turn into a chronic sore throat or sinus infection followed by a potentially dangerous allergy or asthma attack and often pneumonia.

If there was any legal way for me to do so I would tar and feather most of our vendors for putting out pure garbage when it comes to dust collectors and cyclones. Our Federal Government has no standards for the six out of seven small shop professional woodworkers and the innumerable hobbyists except what we put in place ourselves. California does air quality testing for shops that want to go commercial, regardless of fineness of filters virtually all shops that vent inside test with two to five times the OSHA airborne maximum dust levels. Air will not physically carry more than 5 times the OSHA level. At these levels all end up with serious lung damage and one in eight ends up being forced into an early medical retirement. At the permitted OSHA exposure levels 100% of all woodworkers will show a major loss in respiratory function after ten years plus one in fourteen will be forced into a medical retirement. The five times higher ACGIH standard is not much better, which is why the European Union adopted a 50 times tougher than OSHA standard. It only takes moving 25% more air to meet that medical recommendation.

There are lots of problems with all the commercial cyclones being sold by small shop vendors today. A 2 hp cyclone is well under 1 hp too small to even meet the OSHA standards in terms of required airflow when you challenge that unit with the normal resistance of our cyclone, filter, ducting, and hood. The major makers of our 1-micron filter fabric say we need at least 1 square foot of filter area for every 4 CFM and prefer to use 1 square foot of filter for every 2 CFM. Did your claimed over 1000 CFM cyclone come with 500 square feet of filter area? That filter is way undersized which means if it is a real 1-micron filter it is going to plug constantly. It won’t plug constantly because the vendors sell filters that sound good in their advertising but reading the fine print shows they are really not fine filters until they “season”. Seasoning means a filter builds up a permanent coating of dust in the filter pores that does not come out with normal machine type cleaning. I seriously doubt you have a machine cleaner. You get to breathe the fine dust passed by the filter for the typical nine months to a year and a half for one of those filters to amply season that it gives close to the advertised performance. Meanwhile, every time you go in your shop you will see a relatively clean looking shop that is actually building up dangerously unhealthy amounts of fine airborne dust because the filter is good enough to get rid of most of the visible dust. This dust takes years to dissipate and break down. You not only get to breathe that dust while you are making it, you also end up breathing it every time you work in your shop because airflow from our tools, dust collection, air cleaners, fans, HVAC, etc. launch this dust over and over. It will not settle in anything less than perfect still air. Because we do not machine clean our filters, we can easily make matters worse. Too little cleaning and the airflow through the filter is terrible. Too much cleaning and the finest unhealthiest dust passes right through the filter. Adding to this problem all of the major hobbyist cyclones are pretty poor separators and rely on the filters to trap most of the fine dust.

Air engineers learned over three decades ago that to capture the fine dust we need:

Fix most tools with better hoods to block the airflows, contain and direct the dusty air for collection.
A minimum airflow at our larger tools of 800 CFM to meet OSHA standards, 900 CFM to meet ACGIH standards and 1000 CFM to meet the medical recommendations which are now the European Standard.
Either exhaust the air outside or filter it. If you want to filter you then need
a real 1-micron or better filter
roughly 1 square foot of filter area for every 2 CFM
still regularly blow out your shop with a good exhaust fan and
regularly vacuum your shop with a powerful commercial vacuum, e.g. Fein Turbo III
Plus, it is a good idea to also have an exhaust fan to create a negative pressure to avoid contaminating office and living spaces.

To move 1000 CFM against normal shop resistance you need a 5 hp motor turning a 14” impeller with all 7” diameter ducting. Alternatively you need a 15” impeller driven by a 5 hp or larger motor with all 6” ducting. 5” and smaller diameter pipe strangle the airflow unless it is a second port, say the blade guard on a cabinet saw.

1. Should I plumb the entire shot with 6”, instead of reducing my feeder lines to 4”?

A: At the pressures your cyclone blower can generate you will get about 440 CFM with a 4” duct. Imagine low pressure water in a tank. The larger the opening the more water that gets moved.

Main Line:

I have 10’ high ceilings and plan to suspend all the pipe along the ceiling. I have to run the main line (29’) from the dust collector to behind the 8×8 outfeed table so the line isn’t in my way for the table saw. Note: I would like to add a small line to build a shrowd above the blade. The main line will run all the way from the cyclone to behind the outfeed table, then (a 45 – a 1’ length of pipe – to another 45: instead of a 90 degree elbow) , then 5’ down the outside wall to a gate for my table saw. Try to run at a diagonal across your shop with the cyclone located as close to the center of a wall as you can.

Feeder Lines:

I thought the first feeder line I would run would be a broom sweep hood. I am going to have a 45 elbow from the main line, then about 12-14 feet of run from the main trunk line to the outside walls, then (a 45 – a 1’ length of pipe – to another 45: instead of a 90 degree eblow) and then 5’ down the outside walls to the gated wye, then behind the tool.

A: Sounds fine

I would like to have between 4 and 5 branches(feeder lines) coming off of the main line. If I can’t do that, I would probably just have 3 and then use gated wyes.

A: Also not a problem

2. Should I switch the ports over to 6”? Every one of my ports right now are 4”(table saw, jointer, planer, etc), except the port on my bandsaw, radial arm saw and my chop saw, which I intend on building some back hoods for anyway.

A: Yep…I suggest doing it right once…

3. What type of gates do you recommend?

A: Make your own or buy the aluminum non clog type shown on my web pages from Lee Valley

4. Lastly, about the wire for the plastic pipe static build up?

A: You can use either PVC, HVAC steel ducting or whatever you want, but just make sure it is well sealed. Lately the costs have been coming out in favor of HVAC ducting. Home Depot and Lowes both sell duct sealant in a one gallon can next to their metal ducting. It works well and is easy to use.

-- Allegheny Woodshop

4 comments so far

View Dick, & Barb Cain's profile

Dick, & Barb Cain

8693 posts in 4295 days

#1 posted 08-28-2007 04:44 PM

Hi Todd,
It looks like you got a lot of good information from Bill Pentz.

I’m glad you checked out his site.

According to Bill, my system isn’t adequate , so I guess I’m going to have to make some changes also.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN.

View Ethan Sincox's profile

Ethan Sincox

767 posts in 4170 days

#2 posted 08-28-2007 06:00 PM

Holy crap! I had an asthma attack just reading through Bill’s site!

Todd, you should include a link to Clear Vue Cyclones. I’m currently saving up for a premium dust collection system (absolutely necessary per the upcoming move into a basement shop) and I do believe I now have a target goal of $1065 ($995 + the $70 for the filter).

-- Ethan,

View MsDebbieP's profile


18615 posts in 4157 days

#3 posted 08-28-2007 06:38 PM

I’m with you, Ethan.. .gasp gasp.
Makes me want to work outside in the elements and still have a fan blowing everything away from me AND wear my respirator at the same time!!

-- ~ Debbie, Canada (

View jklingel's profile


99 posts in 1153 days

#4 posted 04-15-2018 04:31 AM

i am just searching for bill’s name here, as i just read his web page and think i grasped about 1 or 2% or it…. kidding, but there is a lot of info there. yes, the tone is a bit informercial and often repetitive, but it does sound logical and scientifically based. i am wondering if the simple answer is: crack a window, turn on a large fan as much opposite from the window and possible, and wear a GOOD respirator, even if you have to spend a grand on one. forget the $2K cyclone and just vacuum the accumulated “chips” more often… with your respirator on.

Have your say...

You must be signed in to post the comments.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics