venting outside with a cyclone?

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Forum topic by luthierwnc posted 05-19-2016 02:57 PM 1806 views 0 times favorited 24 replies Add to Favorites Watch
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146 posts in 2017 days

05-19-2016 02:57 PM

Hi All,

I have a good Oneida cyclone collection system in the shop. Almost all of the stationary machines are ducted via 4+” hoses. The choke-point (literally) is the fine dust filter. Wrestling the canister out of the upper housing and manually cleaning it is the most serious downside. Plus, that’s another opportunity to get a face-full of fine particles.

I saw a video by the Wood Whisperer where he bypasses the fine filter and sends that air outside. I’ve tried to find diagrams or a better description of the duct-work needed but haven’t had much success. It seems to me there must be more to it than just pulling the filter and piping the dust on my wife’s roses (yes, there are political considerations too).

In the picture, you can see that dirty air comes in from the right and bounces off the filter canister housed in the upper-body of the unit. Heavier chips fall into the funnel at bottom and the fine particles get sucked into the filter. Cleaned air goes out the center and through the muffler on the left.

So the filter acts as both a collector and a separator. Without the physical filter, debris of all but the biggest size would swirl around and land outside—probably smacking against the fan blades first. It would help to see a diagram on how to force all but the fine dust into the hopper.

There will also be times when I don’t want to enjoy fresh January air to supply the ducts. This is a long shot but an optional bypass would be a luxury worth considering. A little dust from the planer is OK but the drum sander makes only fine particles.

FWIW, I do have a chip separator for the planer. It’s just a Rubbermaid trash can with a weather-stripped lid and two unequal-length 4” PVC pipes for in and out. Much easier to clean than the main hopper.

If anyone has some ideas for doing this well, I’d love to hear them.

Thanks, as always, Skip

24 replies so far

View luthierwnc's profile


146 posts in 2017 days

#1 posted 05-19-2016 03:46 PM

I can partly answer one of my questions. It seems a Thien baffle—or just an elbow pointed below the intake level of the exit port—might solve the issue of bigger chips into the roses. That’s how the planer bucket works but it doesn’t have either the volume or the turbulence of the main cyclone assembly.

More comments still welcome, sh

View Fred Hargis's profile (online now)

Fred Hargis

5242 posts in 2734 days

#2 posted 05-19-2016 04:28 PM

I think part of your poor separation problem is the 4” ducting. To be efficient the cyclone needs to move a lot of air through the body to get the process working. A 4” duct isn’t going to allow that (IMHO).

-- Our village hasn't lost it's idiot, he was elected to congress.

View Kelly's profile


2189 posts in 3185 days

#3 posted 05-19-2016 04:54 PM

Before going to the four inch thing, which is a HUGE bottle neck, make sure you are sealing to the collection bucket. With the unit running, use a smoking toothpick or something (no flame, just smoke) to see if any of the smoke is drawn in at the joint of the cyclone and collector bucket.

If ANY smoke is drawn in, you will start getting debris into the filter.

If your cyclone is working, like mine, the filter shouldn’t see more than a cup of dust, and no chips, after emptying a fifty-five gallon container many times.

After that, at least install five or six inch pipe to tap off of on the output. My Super Dust Deputy has six inch out of the top to a three horse, four bag system, and four inch to the units. It works fine and I have about a quarter cup of dust in the bags, after emptying the thirty gallon drum ten times.

Until I was able to pick up six inch pipe/tube, I ran four and separation was no different that with the six. The only thing that changed, running either my 1-1/2 horse or my 3 horse was, efficiency at the pick up points.

Your Oneida should do every bit as good.

View luthierwnc's profile


146 posts in 2017 days

#4 posted 05-19-2016 06:38 PM

I didn’t explain myself very well.

The existing system works great. You see two 6” lines into the cyclone. The two main lines are 6” as well. The individual machines are typically served by 4” lines but they are straight runs and well gated. It’s tight.

I just want to know if I ditch the filter and vent the exhaust out the wall, if there is enough of an internal barrier to slow the momentum of the big pieces enough to drop them in the bin. sh

View simmo's profile


69 posts in 3713 days

#5 posted 05-19-2016 07:31 PM

Well I vent my 4 ins system out side via a thien style baffle and 90 deg elbows in a 65l sealed drum , just fine dust out chips in drum, if Isee chips on outside then drum need emptying, no problem at all

View clin's profile


974 posts in 1237 days

#6 posted 05-19-2016 09:17 PM

I just want to know if I ditch the filter and vent the exhaust out the wall, if there is enough of an internal barrier to slow the momentum of the big pieces enough to drop them in the bin. sh

- luthierwnc

I think the point is, you shouldn’t be getting chips getting past your separator. The only thing that should be going through your impeller and into your output filter is fine dust, which would be okay to vent outside. If chips are getting through your separator, something is wrong. Once you fix that, you’ll probably find your output filter doesn’t need cleaning nearly as often.

That’s why Kelly was suggesting you test for leaks between the Oneida cyclone and the collection bin it sits on. That must be a good seal or the cyclone won’t work well.

-- Clin

View luthierwnc's profile


146 posts in 2017 days

#7 posted 05-19-2016 11:36 PM

They don’t get through now. It works perfectly. I just want to be sure that it will still work perfectly if the filter isn’t in place.

Forgive the rough illustration but a picture is worth a thousand words. My cyclone filter canister (yellowish) is surrounded by a metal sleeve that hangs from the motor housing. The filter fits fairly tightly into the sleeve except for maybe an inch of clearance at the bottom. The canister itself is a cylinder with weatherstripping around the edge of the top for a tight fit and an enclosed bottom save for a small bolt hole to fasten it in.

Dirty air comes in and swirls around between the outside of the cyclone and the inner sleeve. When it gets near the funnel, small particles are pulled back up into the narrow space between the sleeve and the filter. Heavier pieces continue down to the hopper.

Not to be too delicate but this thing could suck a golf ball through a garden hose. Without the enclosed end of the filter to prevent it, lots bigger chunks could easily be pulled back up into the fan housing and out the exhaust. Noisily, I’ll bet. Maybe a piece of perforated steel covering the bottom of the sleeve could be nutted to the same hanger bolt to discourage that.

I suppose all I have to do is run it without the filter and see what comes out the other end. Again, what I was fishing for was someone to say, “When you run a cyclone without the filter, always put perforated steel on the bottom of the filter cylinder to keep the chips from coming back up like burritos and beer!”

If this is unexplored territory, I’m good with that too. Thanks again, sh

View OSU55's profile


2033 posts in 2230 days

#8 posted 05-20-2016 11:55 AM

I hope you considered that all the air blown out must be made up with air from the outside. If you heat/cool your shop, it will dramatically effect things.

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775 posts in 2608 days

#9 posted 05-20-2016 12:14 PM

That’s it ..leaks at the drum will cause shaving to get in the filter. Home built collection in my projects. I can watch my shavings going into the drum.looks like you have enough over head room for a bigger filter.


View luthierwnc's profile


146 posts in 2017 days

#10 posted 05-20-2016 12:32 PM

Thank you OSU55,

Yep. That’s why I’d like this to be convertible. Running machines that primarily make chips doesn’t clog the filter so fast but the sanding machines do. Sanding isn’t my favorite part of the job so I have lots of those. If I’m going to run the drum sander for an hour, even in the winter, I’d like to be able to pop the filter out and shoot the dust outdoors. The furnace is in the basement which keeps it pleasant but see below:

In a quasi-related thread on Sawmillcreek, I asked about a big exhaust fan to clear out old dust. I’ve ordered a 4,000 CFM snail-shell fan. It will face out of a hole I’ll cut in the only exterior door and I’ll open a window on the far side of the basement for supply. The furnace has to be off for that. Today I’ll get a cheap leaf blower to lift the dust from all the basement surfaces and the fan will blow it outside. Here’s the inspiration for both ideas:

I hope I made the case about mods to the cyclone. Without the filter bottom to deflect the chips, I think all sized pieces would fly out of the exhaust indiscriminately. Dust has to be pretty light to squeeze up into the sleeve and go sideways into the filter. Unless I get an experienced idea, I’ll probably get a piece of perforated screen on Ebay and bolt it across the bottom of the sleeve.

Maybe I’m making more of this than I should but those filters aren’t easy to clean. I don’t have a compressor and even if I did, I’d have to run the hose outside to blast the pleats. Usually I just walk around the lawn smacking it lightly with a stick. Then I might hit it with the hose. It’s never truly clean and I think water just solidifies the slurry into the pores of the fabric so I’m re-starting with a compromised filter every time.

It will still involve chipping through brick for a dryer vent and a 12’ run of 6” hose or vent pipe. I’ll have to unbolt the motor housing from the floor joists and spin it 120 degrees to aim the exhaust port in the right direction. If/when I do, I think I’ll put hard rubber gaskets between the steel housing and the wood so it doesn’t shake the house so much. It’s a day’s work for sure but I’m spending more time in the shop and have noticed a scratchy throat even when I’m not generating fresh dust.

All projects are on hold until the shop is as clean as I can reasonably get it. Time to get smarter. Cheers, sh

View Kelly's profile


2189 posts in 3185 days

#11 posted 05-22-2016 02:08 AM

If that were true, all the chips in my cyclone, which is connected to the collector by six in line, fifteen feet away, would have to go to the collector, then back to the cyclone, after bouncing off the bottom dohicky of a strangely built cartridge.

[ Without the filter bottom to deflect the chips, I think all sized pieces would fly out of the exhaust indiscriminately.]

View luthierwnc's profile


146 posts in 2017 days

#12 posted 05-22-2016 03:37 AM

I can’t speak to “strangely built cartridge”. It’s what came with the machine and has always worked well.

Newer models often place the filters after the fan but the dust chutes inside the cyclone seem proportionally much smaller than mine will be with the filter removed. Probably the big pieces keep going down and the little ones get sucked up. If not, fixing that will be a lot easier than rotating the motor housing and hammering through a brick wall.

View clin's profile


974 posts in 1237 days

#13 posted 05-22-2016 03:44 AM

luthierwnc, I’m confused. Where is this filter at? I assumed it was on the exhaust AFTER the impeller (blower), but does your system have something inside the Oneida unit?

Normally a cyclone has nothing special inside it. Just makes the air travel a circular path and separates the high density debris from air similar to a centrifuge. I good cyclone will collect just about everything except a fraction of the finest dust.

But since you are concerned that removing a filter will affect the cyclone, it makes it sound like this filter is inside the cyclone. Is that the case?

-- Clin

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146 posts in 2017 days

#14 posted 05-22-2016 06:58 AM

Clin, yes, the filter is inside of the cyclone. That’s probably why I’ve had a hard time stating the case. It wasn’t until after my first post in the thread that I realized most newer units have filters after the fan. The filters also seem larger than mine relative to comparable CFM and horsepower. Mine is now 15+ years old and I think it was among the first of the high-end hobby variety. It’s always worked great but I have to clean the filter with the chip bucket which only holds about 40 gallons.

In the Paint picture I posted, the filter is shown as sort of a yellow/gray rectangle inside of the housing sleeve. Debris swirls in a descending pattern just like any other cyclone until it gets about six inches from the joint that holds the funnel to the main housing. From there, heavier chips and most of the dust keeps going down through the funnel to a bin. The finer dust gets pulled by the fan up inside the sleeve, through the pleats of the filter and out the exhaust. The filter canister itself is a fairly tight fit and goes an inch or two above the bottom of the sleeve. The bottom of the canister is shown as black and it is held in place with a wing-nut.

In the original picture you can see a muffler on the exhaust. That’s not a filter. The machine isn’t very loud anyway but I bought it when I got everything else and put it all together before testing.

To clean the filter, you first have to unbolt the ring connector between the funnel and main housing (next to the orange bar-clamp head), unbolt the wing-nut that holds the filter in place and pull it out of the sleeve. Putting it back together takes three hands which is the main reason I’d like to avoid it. Wrestling the funnel level with the housing and fitting the clamp sometimes involves language I won’t share here.

In light of that, I thought I’d ask if I needed to do something to keep the big stuff on a downward path. Without the filter, there is a 10” hole straight to the fan. That’s a much larger opening than the dust collection sleeve in an exterior-filter model. With the filter in, little dust has to creep up through a narrow gap to the pleats. Bigger pieces smack against the bottom of the filter, lose momentum and drop.

I was thinking that by extending the hangar-bolt 2-3” with a coupling nut and bolting a piece of screen (shown in purple) across the bottom of the filter sleeve, I could kill the momentum of the bigger pieces before they swirl up into the air stream, clank against the fan blades and land on my wife’s rose bed. Not an elegant fix but with, say, an 1/8” mesh, I should be able to get the tiny dust out without clogging the sieve. Finding the right sized holes might take some trial and error but most of my woodworking projects do too.

So there you have it. I haven’t sold myself on the project yet but I’d like to at least get the conceptual framework in my head. $15 of perforated stainless steel on Ebay seems a fairly minor investment relative to the new ducts and hoses needed—not to mention chiseling bricks while sitting in a rose bush. Any additional thoughts are welcome and thanks for looking, sh

View clin's profile


974 posts in 1237 days

#15 posted 05-22-2016 03:21 PM

It all makes a lot more sense to me now.

You say that has work well, but I get the feeling it functions mostly as a chip separator and the filter collects large and small dust. In other words the cyclone action isn’t really doing much to catch dust.

You might try contacting Oneida and see what they have to say. Looking at their website, their diagram of a unit doesn’t look that much different than what you showed. Does Oneida still make them this way, with the filter inside the unit?

If I understand your filter correctly, the bottom is sealed, and the air passes through the filter on the sides. What I can’t tell is if this filter is still inside a tube so that the air comes up through the bottom of the tube and flows between the inside wall of this tube into the filter? Or is there just this filter and the air flows right into the sides of it?

-- Clin

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