FWW Article on dust collector modifications

[Peter Hawser]

The latest FWW had an article full of suggestions to improve dust collector performance including baffles and external cyclones. I couldn't help think that what they were really saying was the dust collectors we all buy (other than big bucks cyclone units) are ineffective, inefficient and/or poorly designed. I can't think of another tool in my shop that comes "out of the box" needing so many mods to do it's job (that doesn't count jigs - that's different I think). Other than Jet and their Vortex, do you think other manufacturers will offer some kind of improvements in the standard 1-2hp dust collector and if they do, does it have to cost $700? Or is $700 about right? I really don't know, I'm just asking. FYI, I have a JDS 1.5 hp and bought a canister for it. So I have about $500 into my DC. I tried the old Lee Valley trash can separator, but it took too much of a hit on air movement. Like so many tool purchases, I kind of wish I could go back in time on this one. 2h or more...

[Michael W. Clark]

That sounds about right regarding needing mods to perform up to our expectations. Along those same lines, I think they are one of the few equipment purchases you make that their performance is completely dependant on how they are installed with respect to the system. Your system may have too much loss, but your neighbors system works fine because of less system loss.

[David Kumm]

I thought the article gave some decent information although not much of it surprising. I found fault with a couple of things. The statement that " 400-500 cfm is adequate for your biggest chip producers" seemed kind of arbitrary and I'm not sure I'm in agreement. The testing procedure for measuring the cfm I thought was pretty optomistic as well. A few feet of flex attached to what looked like 6" spiral isn't going to give real world results. Most small baggers are running flex to the machine and the resistance of several more feet of flex and the machine hood itself will drop the cfm a fair amount below their numbers. They did conclude that the 1.5 hp was marginal for use with a separator but I think they still overstated their numbers. Looks to me like 2 hp is the real minimum to deliver the 400-500 cfm- assuming that is adequate. Dave

[paul cottingham]

I also thought they should have used a thien top hat or garbage can conversion rather than the internal baffle. That would have yielded much more useful results for me, and I suspect many others as well. It is also a better comparison external evice, vs external device.

[glenn bradley]

I did a mod on my old bagger just to get me through till I got the cyclone. I too had to remove the separator as it just put too much hit on the flow. With an oversized American Fabric Filter on top and a solid bag below, it still does duty for the jointer. Like a contractor saw; you can add a lot of bells and whistles and get it to sing pretty good but, it will never be a cabinet saw. An inexpensive bag unit will never be a high-end DC. If I could put my DC outside in a shed I would buy a bag unit in a heartbeat as they move much more air for a given horsepower (or cost). Since I have to vent back into my shop, air quality came first. That meant a very fine filter and a cyclone to keep it from clogging up. If I have a busy year I can get about a half a cup of fines in the container below the filter after scrubbing regularly throughout the year. The chip bin gets emptied about once a month but the filter stays remarkably clean.

[paul cottingham]

I made a top hat, and am planning to vent outside. I am pretty happy with the result. It's not a cyclone, but it won't cause a divorce either! It is encouraging me to use more hand tools anyways.

[Phil Thien]

I don't have an answer to your questions (well, I do, but I don't have enough time to type it), but...

Bill Peck from FWW had sent me an E-Mail last year asking if it was okay to write something about the baffle.

We talked (via E-Mail) a few times in January of last year, and then I heard nothing more. I figured maybe they lost interest.

Now to cover a couple of points:

(1) Mr. Peck had originally said they were going to use a General International DC for the test, then subsequently said they'd be using a Jet. I had mentioned to him that the Jet really isn't an ideal choice:

"Oh boy. That snap ring on the Jet DC-1100 often creates a sort of ledge which interferes with separation quite bit. Not the optimum DC for a baffle mod."

The bag retainer on Jet units can result in a ledge around the perimeter of the ring, which obviously is going to interfere with separation. For optimum separation, this area needs to be smooth and uninterrupted.

Units where the bag is clamped to the OUTSIDE of the ring will work better with the baffle. That bag retention method on the Jet is the thing's Achilles' heal, IMHO.

If you have a Jet to which you'd like to add a baffle, do yourself a favor and get a big band clamp and move the bag to the outside of the ring.

(2) FWW seemed to experience filter loading (with the baffle) faster than what I'd expect based on feedback from other baffle users. Of course, #1 (above) would contribute greatly. Other factors can be the rate at which you feed debris, and the type of the debris. So quickly stuffing fines into the hose is going to load the filters faster than slowly feeding chips.

(3) FWW said that when they cleaned the filter, the result was a pile of debris on top of the baffle. They had to remove the filter and brush the baffle off to prevent this pile from just getting pushed right back up to the filter with the next run.

Removing the filter a lot would certainly be a pain. A better option is simply removing the inlet air hose and reaching in with your arm and pushing the dust over the edge of the baffle.

But most of the feedback I get is one to two cleanings a year (from fairly heavy hobby users) where they simply take the filter outside and clean it out.

I really think the key to superior performance is making sure the bag is clamped to the OUTSIDE of the ring. I know it seems simple, but as Mathias Wendel observed in his video at woodgears.ca, a properly executed Thien separator removed more wheat flour than a high-end 3M Filtrete filter. It does work very well, you just have to observe a few rules. Rule #1 has to be no ledges. :)

All in all, I think the article was very favorable. Clearly the Thien baffle outperformed the other solutions in airflow until the filters caked, which required over 100-lbs of sawdust. And had they moved the bag to the outside of the ring, I feel the results would have been that much better.

[Jim German]

I thought it was a pretty good article, not so much for the raw numbers but for the relative effects of the various seperators, as well as showing some cheap and easy ways to improve the perforamance of your DC.

As for Dust collectors not really being ready out of the box, I'd agree. I think alot of that goes down to a lack of understanding by consumers as to how well a dust collector is working, as well as a desire to not pay a fortune for one. Many folks assume that if the DC is getting most of the big chips, its doing its job. If a dust collector is to protect your lungs, it needs to have much more CFM, and a much more effective filter. Even the canister filters on most smaller DCs are woefully inadequate.

Lastly I think most people myself included would perfer to spend their money on toys like bandsaw, lathes and tablesaws instead of dust collection.

[Peter Hawser]

The guru himself posted! :D Mr. Thien, why don't any companies include your baffle? I'm assuming you have been approached?

[Phil Thien]

The guru himself posted! :D Mr. Thien, why don't any companies include your baffle? I'm assuming you have been approached?

Nope, never been approached.

[Andrew Joiner]

Phil, Do you have a patent on it?

[Phil Thien]

Phil, Do you have a patent on it?

The initial finding by the patent office blew all my claims out of the water. I made the decision to abort the process there.

It is a very niche product. Even if I was to license it, the $ returned would be nominal. And I would have to start paying an attorney real money to go further in the patent process after the claims were initially rejected.

Also, manufacturers may be willing to use (in my opinion) less effective forms of a baffle (and sidestep any patent protection) to avoid paying me anything.

[Danny Thompson]

Phil, Do you have a patent on it?

My suspicion is the companies are looking for their own solutions, so they can control the patents and differentiate themselves from one another (e.g., Jet Vortex Cone).

Mr. Thein, you've got a big fan, here, for sharing your ideas for the good of others without personal financial gain. That is what is so great about communities, like this.

[Jay Radke]

It was a decent article and is a help for someone that has an older DC and wants to upgrade without spending more money. Though for someone (i.e. like me) that doesnt have any DC other than a shop vac and a Rockler separator, taking their suggestion to be the best 2HP vac and do the conversion doesnt make sense to me. Since I am a hobby type guy, and with my poor garage door that needs an upgrade so I can work in winter, I am saving up to go right to a 3HP cyclone. Yes its more but not that much vs the time and effort the mod will take. Now if I already had a an old bag model I would go right ahead and do the mod.

The one thing that I find interesting is that we are obsessed with the elimination of fines, which is clearly a good thing for lung health. however at some point we have empty the drums. tipping over the drum into a bag generates plenty of dust, maybe not as fine particles but dust just as well. it wont get as deep into your lungs but will still get in.

[Cary Falk]

I had a Jet 1100 and a 1883(3hp double bagger). I put clear bags on the outside of the lower hoop and canisters on top. I never got the results that everybody else did. I always had a pile of dust and chips on top of the baffle. Sounds like I got similar results to FWW so both of us must have done something wrong. My filters were caked no matter I cleaned them. It doesn't matter now because I have a cyclone now, but I always wondered what I was doing wrong.

[Phil Thien]

I had a Jet 1100 and a 1883(3hp double bagger). I put clear bags on the outside of the lower hoop and canisters on top. I never got the results that everybody else did. I always had a pile of dust and chips on top of the baffle. Sounds like I got similar results to FWW so both of us must have done something wrong. My filters were caked no matter I cleaned them. It doesn't matter now because I have a cyclone now, but I always wondered what I was doing wrong.

It is always hard to say. Some people seem to be able to execute the concept, others struggle. The FWW article is really the perfect case of this, as I told them (in black and white) that the Jet wasn't the ideal test unit. Over a year later, their article appears, and they're using the Jet.

The reality, though, is that the baffle outperformed the cyclone until they ran over 100 #'s of material through the thing. And I suspect (just my guess) that they weren't patient in feeding debris into the unit, either. Had they instead used the unit is realworld conditions, and used the bag outside the ring, I think they would have found an even better result.

Some people are headed towards getting a cyclone no matter what. I equate them to audiophiles that are always upgrading their speaker cables and interconnects. I know a couple of guys like that, they barely even listen to music, and enjoy it. It seems their hobby isn't really the enjoyment of music, but rather the upgrading of their gear.

I know some photographers like that, too. They spend a ton upgrading their glass and buying high-end Xeon workstations for editing photos. One of these guys I know was having a problem and I was working on his computer and realized he had nothing more than tens of thousands of pictures of ... his cat. He had represented himself as a professional photographer, doing weddings, etc. Not a single wedding photo or any other photo of anything but his cat, and some pictures of the inside/outside of his home.

And there is nothing wrong with that. I'm just saying there are a lot of woodworkers that spend more time posting on these forums than they do making sawdust, yet they have a dust collection system which would be ideal for a small commercial shop, LOL.

I've been in some of those and have had owners boast "my filters never get any dust in them." Well duh, I look around and see barely any materials. I ask to see some of their projects and I see a few small decorative boxes.

If you use a cyclone a lot (like Steve Knight uses his CV) you will also find it loads the filters pretty fast. In fact, Steve gave up on cart. filters and build a plenum with bags because he got tired of cleaning his filters.

There are others with Oneida cyclones that have had the same experience, especially when running drum and belt sanders (which generate lots of fines). They sometimes blame the brand of cyclone they have, not realizing that the other brand may only be marginally better.

It really is just a matter of physics. To build a cyclone that get get the finer dust, you need a big (TALL) cycylone. Larger than most people would want to have in their shops. And those are expensive, I know of nobody selling them to hobby woodshops.

[Mark Ashmeade]

And there is nothing wrong with that. I'm just saying there are a lot of woodworkers that spend more time posting on these forums than they do making sawdust, yet they have a dust collection system which would be ideal for a small commercial shop, LOL.


You're bang on the money there Phil. I moved to a bigger shop, and realised that the 4" ductwork I had before just wasn't cutting it. That much was evident when I disassembled it for the move and got covered in sawdust that had been in the 4" PVC. I had one of your design baffles in a trashcan, and it was outstanding at separating the dust and chips. Barely any dust at all got to the bag (a HF unit). The HF unit wasn't going to handle the larger ducting, so I pretty much had to change it all out for a bigger design all round. So now I have pretty good DC, but spend too much time in front of the computer and not enough in the shop!!

[David Kumm]

I wish FWW had also put an oversize quality bag on the collector and compared cfm with the cartridges. I'm one of those guys Phil refers to as having way more DC than is really needed but I'm pretty much in agreement with his take. Cartridges are great on a large cyclone as they take up less room and the cyclone keeps the stuff out of them that degrade the material but the fines still come in. Cyclones for wood shops are pretty inefficient when the particle size drops. My widebelt has a dedicated bagger on it. I would not put a cartridge on a direct unit wih no baffle or separator and not put cartridges on a sander if I had a choice. Dave

[Wade Lippman]

If you use a cyclone a lot (like Steve Knight uses his CV) you will also find it loads the filters pretty fast. In fact, Steve gave up on cart. filters and build a plenum with bags because he got tired of cleaning his filters.

There are others with Oneida cyclones that have had the same experience, especially when running drum and belt sanders (which generate lots of fines). They sometimes blame the brand of cyclone they have, not realizing that the other brand may only be marginally better.

It really is just a matter of physics. To build a cyclone that get get the finer dust, you need a big (TALL) cycylone. Larger than most people would want to have in their shops. And those are expensive, I know of nobody selling them to hobby woodshops.

I would have about 2 cups of fines from the filter when the 55 gallon drum on my JDS 3hp was full; and a decent chunk of the 55 gallons came from a drum sander. The JDS is very short, so the separation probably isn't as good as other; so when people claim they get 2 tablespoons of fines, they might be right though I can't confirm it

OTOH when I had a 2hp DC, I put a separator like the one they tested on it. It got like 90% of the material, but passed all the fines. I found the filter clogged just as fast as ever and it cost a lot of suction; so I got rid of it. Their test confirmed the loss of suction, but claimed it eliminated the filter clogging problem.
I am curious if other people had experience like mine, or like the magazine's results.

[Peter Hawser]

Well, I'm sure Jet thought about their design completely on their own!

[Peter Kelly]

It is always hard to say. Some people seem to be able to execute the concept, others struggle. The FWW article is really the perfect case of this, as I told them (in black and white) that the Jet wasn't the ideal test unit. Over a year later, their article appears, and they're using the Jet.I'm sure that decision had absolutely nothing to do with WMH being a major sponsor of FWW....

[Alan Schaffter]

It really is just a matter of physics. To build a cyclone that get get the finer dust, you need a big (TALL) cycylone. Larger than most people would want to have in their shops. And those are expensive, I know of nobody selling them to hobby woodshops.

As you may know, I have a tall (3D vs 1.64D) cyclone with 3 hp/14" impeller blower- I run it for quite awhile before I need to clean filters, but never put a magnehelic on it to monitor flow and SP so I really can't say if it is any better, and if so by how much.

What I will say, is that configuring it as a push through eliminates the potentially dusty mess of emptying a drum as others have mentioned- I detach a bag, tie it off and carry it to the curb. Where I'm going with this is, where do most folks put the baffle when they are using it with a DC (instead of a shopvac)- before or after the blower? Are any using a trash bag? Most DCs do not generate enough SP to blow up the bag, especially if the filter is not totally clogged.

http://www.ncwoodworker.net/pp/data/1329/medium/P10100382.JPG

http://www.ncwoodworker.net/pp/data/1329/medium/P10100531.JPG

[Michael W. Clark]

Alan,
You are correct regarding the dust bag at the bottom. However, one major advantage of putting the fan after the cyclone is that the cyclone will protect the fan from large objects that could damage the impellor. It also reduces the dust loading on the fan to minimize wear on the wheel.

There are a couple of indicators that are a good measure of performance when it comes to a cyclone and most centrifugal separators. First, is the pressure drop. It is an indicator of how much energy is being put into the device to separate the material. More specifically, the more pressure drop, the more centrifugal force applied to force the dust particles to the wall of the cyclone. The second indicator is the size of the cyclone. The larger the cyclone, the more time the particle is in the cyclone and the greater the chance it has of moving to the wall for collection. Of these two, the size of the cyclone tends to be more important for fines capture. There are limitations on the pressure drop, both practically and physically.

If Alan's cyclone were scaled down by half and still operated at the same volume, the efficiency would drop dramatically even though the diameter was reduced, which increases the centrifugal force. The efficiency loss is going to be most seen on the fine particles due to the efficiency curve of the cyclone. The amount of material that passes the cyclone is unknown unless we know the particle size distribution of the dust entering the cyclone. If most of the dust is 50 micron, the cyclone will probably still be very efficient at this size. If most of it is 5 micron, there will be a lot more dust that passes as a % of weight.

Cyclones that "fit" in most home/hobby shops are not going to be very good at the smaller particles, <10 micron. Depending on the proportional dimensions and the specifics of the cyclone design, you may get good separation down to 5 micron. Cyclone separation at 1 micron is not going to happen with most ceiling heights and budgets.

[Jim German]

I'm sure that decision had absolutely nothing to do with WMH being a major sponsor of FWW....
There aren't many dust collector makers that aren't sponsors.

Using a DC that isn't optimal for the baffles seems like a good thing to me, as it shows that there can be issues its use. I'm surprised that Phil thought so poorly of the article, as it seemed very favorable towards the baffle to me.

[Phil Thien]

There aren't many dust collector makers that aren't sponsors.

Using a DC that isn't optimal for the baffles seems like a good thing to me, as it shows that there can be issues its use. I'm surprised that Phil thought so poorly of the article, as it seemed very favorable towards the baffle to me.

LOL, there can be issues with the use of anything. You can have issues driving a Porsche 911 Turbo around with low-octane fuel in the tank. But when Car and Driver does their reviews, they use the recommended fuel.

Pointing out a problem doesn't mean I'm upset or think poorly of the article. Nothing could be further from the truth, I loved the article.

[Jonathan Clement]

My wife and I found that FWW article very interesting and it helped us determine that we could make at least one more improvement to our system. We already had a fiber barrel separator, but figured that replacing the 1 micron bag that came with the Delta machine with a Wynn NANO filter would improve the dust situation in our basement shop. The filter fit perfectly using the edge trim gasket that Wynn sells to accompany the filter.

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[James White]

Jonathan,

How much of a hit would you say you took with the addition of the separator?

James

[Jonathan Clement]

James,

When you say "hit", what do you mean?

Jonathan

[James White]

James,

When you say "hit", what do you mean?

Jonathan

A loss in suction.As compared to no separator.

James

[Jonathan Clement]

James,

We don't have any way of measuring, but no noticeable loss as far as I can tell.

Jonathan

[Michael Dunn]

Awesome thread!!! Lots of great info. Where can I find more info on the filter mod that Paul designed? Or whatever it is.

[Jim Neeley]

Hey Michael,

Google Thein Separator.. it will take you to Phil's site an a plethora of discussions on it vs. both trash can and cyclone separators. You will see opinions are like noses: everybody has one. <g>