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Forum topic by Absinthe posted 06-26-2011 08:45 PM 6874 views 0 times favorited 15 replies Add to Favorites Watch
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Absinthe

84 posts in 1996 days


06-26-2011 08:45 PM

I am starting this topic merely to discuss the hows, whys and wherefores, as well as qualification and quantification for some of these things.

After doing some research, it would appear that people use several different strategies for dust collection. Everything from, NOTHING, to some wild multistage hybrid systems that are so far beyond my budget I can’t really even consider them.

It would appear that simply using a shop vac, or blower with bag filter is frustrating at best because the filtration clogs up fast and suction pressure goes away… seems counterproductive. And the ultimate in better than nothing.

So at the very least, some kind of chip collection needs to happen. There are a few pre-made and home made bucket, barrel or can toppers that by virtue or the inlet going sideways and the outlet sucking from the center, separates most solids but still allows dust/fines to hit the filters. This is pretty much the internal design of most shop vacs and specifically my huge-ass Genie shop vac.

Then comes the new internet holy war :D mini-cyclones and Thien separator.

The mini cyclones seem to fall into a few camps. The strict Pentz based cyclones, which I think the only non-homemade ones are the Clearvue Mini and some other brand that I don’t think is actually sold anymore. Homemade ones seem to either settle for close-enough or take painstaking steps to get it dead on. Sometimes these include a funnel and other times it is simply a long column. It seems from my reading that the 6” Pentz one (for shop vacs) is a compromise from the recommended 5hp 18” serious one (and the 8” one that am building will no doubt be a compromise as well). In this same area is the smaller Oneida Dust Deputy, (I will have one to play with shortly) and it looks cool. One of the suggested configurations involves running two in series, which may be an effective idea for keeping the most dust/fines out of the filters. But, where does one draw the line? How many smaller ones in series is as good as one large one. I have seen numbers such as the big industrial ones built for the AG industry with an 85% efficiency to what Pentz claims as “low 90’ %” from his modifications and calculations.

The Thien separators tend to essentially be focused on a baffle below the out let. The proper Thien baffle appears to be based on a 240° drop slot in an otherwise fully blocking disk. I assume this works by merely not allowing the solids to reemerge near the outlet by trapping them below. I believe delta has a ‘Vortex’ which appears to be a dome added on to their drop box (though as far as I have heard, not offered as a retrofit or upgrade. Interestingly enough, this appears to be a dome that is convex toward the outlet. This has raised some ideas to me. It seems that some separators are complete and others are based on the bucket/can toppers and simply adding the baffle to it.

Terms like ‘good enough’ and ‘less expensive’ ‘just as good’ and things like that are hard to truey quantify or qualify. Granted, when you look at Pentz stuff, he obviously has the scientific data and measurements and general laws of physics to cite. However, in other things all I usually see are purely anecdotal. I also don’t see too many people that have both systems and some way to compare the results.

OK, now I have shared everything I have internalized so far. I have ordered one of the Oneida Dust Deputies (the small one with the buckets). I am also in the process of building an 8” Pentz based one. I will also make a couple different Thien based baffle barrel topper ones. One of the things I want to try is using an 8” vent cap as a baffle with a 4” outlet centered inside it, with the input at some level below it. My hypothesis on this is that if air rising across the conical cap should slow enough to drop out material before coming into the output area. Not sure how that will work, but if it does well, it would be reproducible with off the shelf items.

Another thing I have seen are tapered ducting reducers. At least from the pictures the ones that go from 8 or 6 to 3 or 2 and have a long straight part. If these are long enough to have that 3:1 top opening to bottom opening with the 1:1.64 top opening to cone length they might make for another off the shelf starting point for small home use cyclones that meet the Pentz ratios. Along with some plastic soda bottle’s that share similar shapes I will experiment with these as I get a hold of them.

If you have read this far then you are either a masochist, or you share my interest in this area. What I am looking for at this point are some ways to measure the effectiveness of one over the other. I am also curious of a combination between the two. Perhaps the use of a Thien baffle either in conjunction with or replacement of the air ramp in a Pentz style cyclone. As well I am interested in other shapes used for the baffle or even simply the air ramp without a following cone.

Anyway, this is more of an invitation to conversation than a specific question. I plan on playing, but I am not promising to do it all in a timely manner. :)

-- Absinthe


15 replies so far

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BlankMan

1488 posts in 2818 days


#1 posted 06-26-2011 09:05 PM

I guess I’m a masochist. My dust collection system is on it’s 5th generation. 4th was finally an Oneida cyclone with internal filter, 5th converted it to a 3 times the size external filter along with a different internal baffle tube.

I take dust collection seriously and have two overhead air filters also. Everything is sheet metal plumbed using 5” mains to each machine. I hate dust.

I am satisfied with this setup finally and don’t foresee any future changes. I long ago decided I want to make woodworking projects and not for the shop projects like I used to. ‘I can save money if I build it myself…’ But sometimes I land up spending more, not to mention the time, so I now consider that and sometimes just bite the bullet.

Be interesting to see the results of your project though, I’m always interested in getting that last speck of dust.

-- -Curt, Milwaukee, WI

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Absinthe

84 posts in 1996 days


#2 posted 06-26-2011 09:19 PM

I hold a warm place in my heart for the masochists out there. :)

I have a brand new ‘shed’ that I am turning into a wood shop. So anything I build to help the process is fun. I am sure at some point it will become ‘work’ and then I will stop and just make other projects :)

I do know in my heart that whatever I do now will make life easier later.

-- Absinthe

View David Grimes's profile

David Grimes

2078 posts in 2104 days


#3 posted 06-26-2011 09:31 PM

More of a sadist here, but we do tend to gravitate to where the masochists are… ;=)

I think it is great that you have determined to build / compare these and report the results. I was fully prepared to do the same, but I got lucky and got mine exactly right the first time.

I will not bore with my setup details as you can find it here: http://lumberjocks.com/topics/26968 and here: http://lumberjocks.com/topics/25969.

I seriously have not even slightly negatives with my system in my shop. Right now I have nothing but fines and dust out of the machines I attach… other than the occasional small pile of planing curls. Mine gets all of that. I realize that my rig might choke (sadist pun intended) elsewhere, but I need nothing more at this time. When I add a planer or a lathe, then I’ll see and re-evaluate, but i am hoping that such great service for the fines and dust is the hard part that has been overcome.

I anxiously await the results of your experimentation.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

View dbhost's profile

dbhost

5607 posts in 2697 days


#4 posted 06-26-2011 09:56 PM

I guess I fall into the masochist category. While I would LOVE a true Pentz type cyclone, they are just too far beyond my budget to be attainable without cutting budget elsewhere… And I have hacked my budget pretty tight as it is…

My system itself is on what I would consider the 4th generation. The first being merely a shop vac. Clogs came quickly and it was found to be badly ineffective. Second generation was Shop Vac / Thien separator in a trash can / HEPA filter. It worked well, but was chip collection at best. Third generation was Harbor Freight 2HP DC / Wynn Filter / Thien baffle. Great for space usage, great fro separation, terrible when cutoffs would get sucked up and hit the impeller. The 4th generation came in 2 stages. First stage was removing the Thien from INSIDE the DC, and building a full on separator in line out of a 55 gallon drum. It initially had 4” ports. I have since ducted it with 5” in and out, and went with a 5” side inlet.

I can’t tell you in scientific terms how efficient it is, but I can say that the only dust I get in the shop is from equipment not yet rigged with sufficient dust hoods (lathe, drill press, and miter saw). I have been using this rig now for over a year in this generation, and have found that after no less than 6 empty cycles of the dust bin, I still have less than 1 cup of material in the bag of the dust collector…

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View Bertha's profile

Bertha

13003 posts in 2158 days


#5 posted 06-26-2011 10:02 PM

You can’t go too hardcore with dust collection, in my humble opinion. My shop is around 20’x10’ and I’ve got a 2hp and a overhead. I worry more about “overhead” units, since I’m a handtool guy. It’s amazing how much my JET coarse filter grabs. It’s scary, really. If you’ve got an Oneida fed with 5” pipes and an overhead filter, that’s reasonably hardcore in my book. A trashcan separator fed at the 4” level made a big difference in my shop. You could probably skip that step with an aggressive cyclone. It’s all expensive, my friends. I’ve developed an allergy for some woods and not walking around hacking and covered in hives is worth a bit of money for me. Good luck, my friend. You know more than me about this.

My next dust collector is going to be the Gorilla. Yellow and loud, heck yes.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

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Bertha

13003 posts in 2158 days


#6 posted 06-26-2011 10:07 PM

You could always go all out:

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View David Grimes's profile

David Grimes

2078 posts in 2104 days


#7 posted 06-26-2011 10:35 PM

Oh… almost forgot… and my dust system is entirely put together with gorilla glue. ;=)

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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Bertha

13003 posts in 2158 days


#8 posted 06-26-2011 10:37 PM

You win, David! Lol at gorilla glue. I use it, but lol nontheless.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View Absinthe's profile

Absinthe

84 posts in 1996 days


#9 posted 06-26-2011 11:13 PM

Gorilla glue, now why didn’t I think of that.

The issue with comparison, is how to tell how much ends up in the filtration, or worse yet passes through.

-- Absinthe

View Bertha's profile

Bertha

13003 posts in 2158 days


#10 posted 06-26-2011 11:30 PM

Absinthe, breathing in wood dust is no joke; we make it a joke at times, but it’s serious business; almost as serious as the internet;) I’d have a 7.5hp Oneida in my 20’ shop if the fiance’ would go for it. I’d recommend going as crazy as your budget permits. A Trend shield is only a few hundred bucks; you’ll look like an Alien, but the protection’s hard to beat.

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

View Manitario's profile

Manitario

2402 posts in 2348 days


#11 posted 06-26-2011 11:45 PM

I’m not much of a masochist, but the inner geek in me loves these topics. My own foray into DC started with nothing, and a lot of coughing and allergies. Next step was a 1 1/2 HP General Int. DC with a 1 micron canister connected to my machines with 4” flex duct. This collected a lot of the sawdust, but I still would come in with a lot of coughing and running nose. I read more, and exchanged the 4” flex duct for a short length of rigid 6” duct, with short runs of 4” to my machines. Again, an improvement, but still allergies. My latest DC version is still in a box in my garage. I am in the process of moving to another house with a larger garage, so I felt it was time to pull the trigger and buy a Pentz cyclone from Clearvue. My plan is to use proper 6” ducting right to the machines…. I see the utility of using a chip separator with a 1 stage DC; but it is a catch 22. It keeps the filter cleaner, and therefore keeps the DC at maximum efficiency. The other side though is that a chip separator introduces a large amount of static pressure into the DC system which, for most typical 1-2HP canister DC is enough to keep the DC from capturing the fine dust that is carcinogenic.

-- Sometimes the creative process requires foul language. -- Charles Neil

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Bertha

13003 posts in 2158 days


#12 posted 06-26-2011 11:47 PM

Rob’s going 6” Clearvue to the machines. Gangsta. Good looking out, Rob:)

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

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Manitario

2402 posts in 2348 days


#13 posted 06-26-2011 11:50 PM

Ha, thanks Al! “Go hard or go home”

-- Sometimes the creative process requires foul language. -- Charles Neil

View Absinthe's profile

Absinthe

84 posts in 1996 days


#14 posted 06-27-2011 12:14 AM

Well I am learning a fair amount about metal working in this process. Who knows, maybe I will end up doing more metal work and less wood :)

Or maybe I will make more metal woodowrking tools. :)

-- Absinthe

View crank49's profile

crank49

3981 posts in 2436 days


#15 posted 06-27-2011 05:49 AM

This probably isn’t the place to sing the praises of the Harbor Freight 2hp dust collector, but I have one, it works well, and I like mine.

- The addition of a drop out collection device in front of the dust collector’s fan is a very good idea because it catches big junk before it goes through the fan and the can is much easier to empty than the bag on the collector. This drop out device can be a thein separator, a cyclone, or just one of those “cyclone lids” for a regular metal trash can. I vote for the “lid on trash can” myself because it is cheap; consistent with the HF collector.

- You can get to this point with a total investment of less than $200 and you will catch most of the dust generated in a typical home shop. But, you will not be collecting the fine, under 5 micron dust.

- This is the point where I have a little different priority than many other LJs. The dust collector in my shop is noisy. I only run it when I am actually running a tool, like the table saw or jointer etc. I also know I make dust that the collector is not hooked up to; like hand sawing, jig sawing, hand sanding, things like that. For me, the next most important priority is the ceiling mounted air filter, which is not noisy and runs all the time I am in the shop; and even for a while after I leave with a timer. This filter can be bought for about $250, or shop made for less than $100, and keeps the air in the shop much more healthy and safe.

- The last priority for me is the modification of the dust collector to replace the 5 micron bag with a 0.5 micron filter cartridge. This greatly increases the surface area of the collector and that gives less resistance to air flow. The result is a cleaner shop and improved flow through the collector. The cost to change a bag type colletor to a cartridge filter is about $150.

- Bottom line, all this can be put together for less than $500, but the entry level first step is about $200.

AND, there is still a place for the shop vac, with or without a little cyclone installed on it. Most portable power tools like ROS and belt sanders, and routers have ports or connections for dust collection and these tools are actually better handled with a low volume, high pressure, high velocity type collector, like a shop vac. The reason is the need for smaller, more flexible hoses and the high rpm of the tool itself (in the case of the router).

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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