What will I gain by using a baffle in my 2-stage DC?

[Mark Burnette]

I have a 2HP Cincinnati Fan DC that has a home-made shroud mounted around the impeller intake. This shroud limits my drum capacity so I was wondering what would happen if I replaced it with a Thien or "wok" baffle or simply removed it entirely.



Unlike most the experiences I've read here I've never felt I have a problem with too much dust getting into the bag--except when I forget to check the drum and the level gets up to the shroud. First I needed to test how much dust was getting past the swirling vortex in the drum, past the shroud and into the bag. To do this I took about 1/3 drum of varied sawdust (planer & jointer shavings, TS dust, sanding dust, floor sweepings...pine/oak/plywood/PT/MDF were all in there). I sifted the dust through a 1/4" soil sifter to remove any chunks, then weighed the empty drum.


I would then suck up the dust and weigh the bag & drum, then empty both into a clean trash can and re-weigh everything to make sure the numbers added up consistently. I did this 3 times as I refined my technique and in all cases the numbers repeated within .1 pound out of 28 pounds of dust (the scale is a calibrated 200 lb unit with .05 lb resolution). I then repeated the test with the shroud removed.

Results: With shroud in place I would get 1.1 lbs of fine wood "flour" in the bag out of 28 lbs total, or 4%. With no shroud I got 1.4 lbs or 5%.

I put a 4 foot fluorescent fixture behind my drum while I was sucking up the dust and could see the swirl through the translucent drum. I couldn't tell any difference in the vortex speed or pattern with/without the shroud. At this point I don't know if I will gain anything by making a different baffle but I will gain lots of drum capacity if I run with no baffle.

I'd love to hear from others who have baffled their 2-stage DC (not a "trash can separator"--that's been well covered). This DC seems to perform much better than other 2-stage units I've read about (and that's not very many--for whatever reason this type was never very popular). I've run this system unchanged for almost 20 years in my current house, and for several more in a basement shop before that. It's not "ideal" but it does the job.

[Bruce Wrenn]

I have a similar DC (Delta) that I removed the fan assembly and mounted it on top of a Wood Magazine cyclone. Mine's only 1.0 HP, but it does everything I ask of it, including keeping up with my 15" planer. Unless you have changed out the filter bag, you have a dust distributor, as the bag only traps largest of stuff. Kinda like using hog wire on a screen door.

[phil harold]

I modified my HF with a Thien seperator
without the bag on, it put out only a fine powder
less dust then then my 1hp delta with a 30 micron bag

http://www.sawmillcreek.org/showthre...hien-Collector

[Lee Schierer]

I put a Thein baffle in my Delta Dust collector, that sits on a 55 gallon drum. The drum used to get 1/3 full and then the bag would start filling up. After installing the baffle, the drum now fills more than 2/3 full before I start getting shavings in the bag. Since the bag doesn't get shavings as quickly, the performance stays better longer.

[Curt Harms]

I put a Thein baffle in my Delta Dust collector, that sits on a 55 gallon drum. The drum used to get 1/3 full and then the bag would start filling up. After installing the baffle, the drum now fills more than 2/3 full before I start getting shavings in the bag. Since the bag doesn't get shavings as quickly, the performance stays better longer.

Lee's experience is very close to mine. The Thien baffle really helps with larger particles, some 'flour' still makes its way into the filter. Letting the bag contents get closer than about 10" to the baffle result in more stuff getting into the filter. A clear bag makes it pretty easy deciding when to empty the bag. I'm not sure how much the O.P. would gain except for being able to get more in the container before emptying.

[Mark Burnette]

I tried to be thorough in my post and anticipate all the little things that sometimes derail posts (how did you measure, was it calibrated, etc). Maybe it was too long & I bored everyone

I get so little dust in my bag (a 2 micron bag, I think, not original) I'm questioning if I should bother with a baffle. And the closet the DC sits in has never been cleaned in 20 years so I don't have a problem with fines blowing through the bag. This doesn't seem to match anyone elses experience with this type of DC. I will say mine came from a factory that used it on a graphite process so it was likely chosen for its performance with trapping very fine dust.

[Lee Schierer]

As I mentioned, the only real gain was more shavings and sawdust collected between emptying. As far as I can determine, there was no downside to installing the baffle.