Phil Thien's Baffle and Bill Pentz

[David Hostetler]

I am not trying to disparage Bill's work in the slightest, and as I have mentioned, intentional or not, the impression does come through that Bill is opposed to anything but a full blown cyclone setup.

In theory though, a cyclone is just a separator, hooked up to a big 'ol impeller and motor, usually hooked up to a large (6" or bigger) duct.

I think we all agree that the basics of dust collection are...

#1. Hoods. You have to be able to draw the dust in for a dust collector to do its job.
#2. Airflow. See #1, likewise you need to keep the dust suspended until you get it to the collection chamber.
#3. Filtration. 1 micron or lower filtration is best.

The cyclonic chamber as well as the Thien separator both are there to address issue #2. Without separation, chips and fine dust will quickly clog up any filtration media. I have not seen any air quality analysis test results comparing the effectiveness of separation and air flow between say a 3HP DC sucking through a cyclone, and a 3HP DC sucking through a Thien baffle / separator.

The assertion that Bill gives RE: 4" plumbing is most likely valid in that 6" plumbing has the capacity to move more, but if you are capturing 95% with 4", and 97% with 6", you still have SOME ambient dust. Unless I am missing something, there is no dust collection setup that gets everything, the point is to minimize your exposure to the best of your ability. So to say that a full on high HP cyclone pulling through 6" or 8" duct will completely protect your health is a bit of an overstatement as well.

Now, read my opening statement here again... I am NOT dismissing Bill's extensive research, but I agree with Jim O'dell that Bill seems to be pitching one approach as best, which is fine, but most of us cannot afford the "Best" or we would all have shops filled with Mustard, or Black, or, well pick your color, and Harbor Freight would be out of business. That simply does not address the reality many of us live with.

And on the issue of health protection RE: dust collectors and cyclones, any effort to minimize your exposure to the fine dust will make great strides toward protecting your health. But like was mentioned, even with a full on cyclone system, Bill himself uses a respirator to protect himself.

[Phil Thien]

If all you want is a clean shop, then Phil's separator (especially if coupled with a hanging air filter) will help give you that, and a lower cost and quieter to boot. But don't fool yourself into thinking that you are protecting your lungs.

It seems like a few people are writing-off the baffle as chip collection only. Nothing could be further from the truth.

Before I found the Dylos meters and then organized the group, there was a misconception out there that the finest dust never settles, and shops w/o big cyclones were akin to toxic waste dumps.

The "Dylos Experiment" put that one to bed. I don't remember a single post from a Dylos purchaser that said, "hey, I set this thing up and went to town on my table saw and found that my cyclone works so good the #'s didn't budge."

What I do remember was an avalanche of E-Mails and phone calls from people (many with cyclones) saying, "I have more work to do."

There are three issues involved in good DC:

(1) BIG CFM. This can certainly be achieved with or without a cyclone. A single-stage unit w/ a giant blower can certainly get you the CFM you need.

(2) GOOD SEPARATION TO KEEP YOUR FILTERS CLEAN. A good cyclone will certainly outperform the baffle. However, for many weekend warriors, the baffle will provide plenty of runtime between filter cleanings. And it is important to remember that NOTHING keeps your filters from loading over time. A good cyclone will load them more slowly than the baffle, but they will get loaded.

(3) GOOD COLLECTION AT THE TOOL. Perhaps the largest surprise for most Dylos buyers was the fact that attaching a big cyclone to their cabinet saw wasn't enough. If you want to capture the fines on a table saw, you gotta have above the table collection, and you may have to open-up the cabinet's port, too.

In my first message above, I was not admitting defeat to the cyclone in any way whatsoever. I have corresponded w/ people using the baffle in their single stage that have lower Dylos readings than other people w/ cyclones.

So to recap: The only advantage of a good cyclone over the baffle is separation efficiency. You can absolutely build a system with one or more baffles that will keep your air every bit as clean. You may just have to clean the filter more often.

[Joel Earl]

The 'debate' between Phil's separator and Bill's cyclone is cleanlliness vs health issues. As a security technician, I would say that if you use Phil's separator and are expecting health protection, you have a false sense of security and that can be dangerous. To get the same HEALTH benefit you would need to still wear a respirator.

If all you want is a clean shop, then Phil's separator (especially if coupled with a hanging air filter) will help give you that, and a lower cost and quieter to boot. But don't fool yourself into thinking that you are protecting your lungs.

I have said before this - if you want real health protection and a security blanket in having such go seek out a sterile medical or NASA clean room as that is about the only place you likely will >> honestly<< find it to occur. Fact
I use Phil's pre-seperator. It does all I want and expect of filtration. Bill's would give me more sucky - not needed in my shop. The other stuff .... well, I won't go there.

I go outdoors - I have air that is not perfect. I drive an auto, I cook, I swim in lake water and oceans ---- and on and on.
You are in shops and hopefully working with wood. It "may" cause harm. Generations and generation of folks have been okay and not harmed too. Without the cyclone in their shops at that.
I sound like a soap opera so sorry.

[John Coloccia]

What's interesting, Phil, is that just turning my cyclone would send the Dylos into the stratosphere. I found that while I was collecting moderately well at the tool, the filters would build up a static charge and everything floating around got stuck to my filters. Turn the cyclone on, and wham...all over the place. When I added my JDS air cleaner, that problem went away. It's pretty amazing what an air cleaner can do. IMHO it doesn't help you much as you're working. What it does is clean the air when you're done stirring up junk so that the next time you walk into the shop you don't make a cloud of fine dust.


That Dylos is one of the best investments I ever made.

[Phil Thien]

I found that while I was collecting moderately well at the tool, the filters would build up a static charge and everything floating around got stuck to my filters.

But why would a static charge on the filter cause a spike in the readings of the Dylos? Wouldn't it cause a decrease in the reading as more and more of the airborne dust clings to the outside of the filter?

[John Coloccia]

Because it would collect the dust that was floating around in the air after I left for the night. When I flipped it on the next morning. the airflow out of the filters would blow all that collected dust to kingdom come. LOL. Quite funny actually, when you think about it

[dan sherman]

Never mind, John responded while I was typing

But why would a static charge on the filter cause a spike in the readings of the Dylos? Wouldn't it cause a decrease in the reading as more and more of the airborne dust clings to the outside of the filter?

[Peter Aeschliman]

Well articulated post, Phil.

Thanks for your invention, by the way. I installed 2 baffles in my Grizzly 3 HP single stage double bag unit and added Wynn filters. It works awesome from what I can tell!

[Alan Schaffter]

Time to jump in here.

What everyone is missing is the best option. The reason many people are using cyclones or baffles is to separate out the dust, to make it easier to dispose of, but more importantly to extend the life of their filters both from clogging and needing to clean, and extending the life of the media (cleaning breaks down the filter media).

Dust clogs the filters and reduces CFM from end to end in a DC system- yes it reduces CFM at the source, right where you want to collect it. Even cyclones and baffles pass some dust onto the filter- where it either (A) gets captured and so doing reduces CFM in the system, INCLUDING collection at the souce!!! or (B) passes through the filter back into the shop environment- there is no (C)!!!- neither option is acceptable in my mind. The better the separator, whatever type, the longer it takes for (A) to happen, but it still happens. Even a clean filter reduces CFM.

So what is the solution. Use a separator and discharge outside, NOT into a filter. Without a filter you are starting off better than you will ever be with any type of filter. Commercial shops typically discharge into external bag house filters.

As to heat loss, unless you are a commercial shop, or run your DC continuously, it is not the problem you think. The thermal mass of the shop walls, floor, ceiling, benches, and tools is much greater than that of the air in the shop. If you go to this Wikipedia link and look at the tables of "specific heat capacity," which is the measure of the heat energy required to increase the temperature of an object by a certain temperature interval, you will see that gypsum, wood, etc. etc. have a heat capacity over 1000 times as much as the same volume of air. So just like opening and closing your fridge door, you can let in volumes of cold (or hot) air and the shop surroundings will quickly warm (or cool) it until equilibrium is reached. The tradeoff a few pennies more in heating or cooling costs, or MUCH cleaner air in your shop.

And yes, Bill Pentz will agree this the best DC configuration. Phil?

[John Coloccia]

That's a great point, Alan. In my case, I have to exhaust into a filter because my shop is very tight, and my furnace is right in the next room. I would need to bring make-up air directly from the outside, which is VERY cold in New England. Sometimes I run the DC for an hour when I'm turning or doing a lot of sanding. My heater just wouldn't keep up and my shop would be very cold, very quickly. If my configuration were different, I would absolutely vent outside.

[Phil Thien]

Time to jump in here.

And yes, Bill Pentz will agree this the best DC configuration. Phil?

Before I answer that question, can I have a more concrete figure for how much energy (natural gas) it would take to heat 48K CF (800-CFM at 60-min) from -5F to 70F?

Anybody know the answer? Not trying to be a stickler here or anything, but the energy from the thermal mass isn't free, I had to burn gas to heat my walls up, too.

So if someone could compute that for me, I can give you a better answer.

[dan sherman]

Before I answer that question, can I have a more concrete figure for how much energy (natural gas) it would take to heat 48K CF (800-CFM at 60-min) from -5F to 70F?

Anybody know the answer? Not trying to be a stickler here or anything, but the energy from the thermal mass isn't free, I had to burn gas to heat my walls up, too.

So if someone could compute that for me, I can give you a better answer.

if this link is right
http://wiki.answers.com/Q/How_many_b...f_air_1_degree

64,800 btus, assuming 100% efficiency.

[Mark Engel]

I think if I left the refrigerator door opened for 60 minutes with an 800 cfm fan inside blowing out.... well, you get the picture.

Some analogies just don't hold up.

[Thom Sturgill]

Phil, I wasn't meaning to slight your separator. I was primarily responding to the thought/attitude that partial collection was better than none so 85% is good enough because I can't see the rest. And to the danger of having a false sense of security.

Obviously if you are measuring, you can potentially improve collection, and have some reality on what is being missed. It does not surprise me in the slightest that people that measure get better results than people who don't regardless of whether they have an expensive cyclone or a separator. But the attitudes that I see reminds me of hard-core smokers (I used to be one, my father died of lung cancer) and second hand smoke.

I am a wood turner, and as such primarily use the machine that's the hardest to collect from. I can think of no other machine that poses the problems a lathe does and I've owned or used most of the machines found in a wood shop.

All that said, I own an underused HF DC with Wynn filters and an air filter and intend to add your separator, I just don't delude myself that that's as good as it gets, and will continue to wear a mask while sanding.

[Jeffrey Makiel]

Phil...it's been a while since I used this part of my brain.

If your shop was fully warmed up to 70F and you turned on your dust collector which exhaused outside and had a window open to let the make-up air in...

BTUs/hr = Cp x Mass flow x delta Temp
BTUs/hr=1.08 x 800 x (70-(-5)) = 64,800 BTU/hr

Natural gas gives about 1000 BTUs/cubic foot...

64,800/1000 = ~65 cubic feet

Assuming your home heating system is 85% efficient...

65/0.85 = ~76 cubic feet of natural gas is actually used if you run your dust collector for 1 hour (continuous or in aggregate). Just multiply this number by the cuft rate on your gas bill to receive your heart attack.

-Jeff