DIY Dust Cyclone Woes

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Forum topic by TysonK posted 08-28-2016 08:38 PM 1122 views 0 times favorited 11 replies Add to Favorites Watch
View TysonK's profile


154 posts in 2651 days

08-28-2016 08:38 PM

Looking for advice and help from those of your who know your dust collection better than I. (That probably means most anybody)

I’ve been working for several months on dust collection, which included building my own cyclone. I have built a smaller version for a shop vac and it worked well, so thought I’d try a large version. It’s roughly 30” tall, 20” wide at the top, and the inlet is a 6” pipe, extends ~10” into the cyclone connecting it to the blower motor. My blower is a 2HP Jet and it vents into a Wynn filter.

I knew it wouldn’t be as efficient as a commercial version, but still, anticipated that it should work pretty well. I read up the info from Bill Pentz, I even built another cyclone that was much taller according to his recommendations but for various reasons scrapped that build and completed this one. After everything was connected it seemed to be working really well. The inside is coated to make it smooth, so it’s not all segmented like the outside.

After a few hours in the shop yesterday I noticed dust getting all over stuff and later realized the filter was so clogged that the air was just breaking the seal and blowing dust out from the filter. I’ve not had this system up and running for very long, and I’m also seeing a lot of large dust and chips in the filter, not just the tiny stuff that you’d expect.

Does anyone have thoughts on why this might work so poorly? At this point, it’s pretty discouraging, and I’m looking to just buy a Super DD, but still wondering, how did it fail so miserably? Even a basic cyclone should do a better job at separating the larger particles from the small stuff?

- When the filter starts to clog does it effect the cyclone because air can’t move as well?
- Is this just a bad design and a better design or commercial version will make a large difference or prevent this from happening in the future?
- Anybody have similar stories or woes with dust collection? I’m ready to take a bat this this system.

-- -- Tyson

11 replies so far

View daddywoofdawg's profile


1029 posts in 2424 days

#1 posted 08-28-2016 11:18 PM

My first thought would be that the motor unit is too close to the cyclone and it’s just sucking everything up and not giving it a chance to “cyclone”.Maybe moving the motor unit and placing hose there and then to the unit may help.Look how the commercial units are setup,the motor unit is separate from the cyclone filter section.
I know nothing but that’s what I would think.

View WhyMe's profile


1309 posts in 2410 days

#2 posted 08-28-2016 11:39 PM

So the inside cylinder that the blower connects to extends well below the level of the side input/suction connection. Have you checked for air leaks at the collection drum which may be reducing the cyclonic effect?

View htl's profile


5211 posts in 2008 days

#3 posted 08-29-2016 12:15 AM

Must be sealed completely, and may need to try different lengths to the pipe that hangs down into the cyclone chamber.
There were a few times I didn’t get my bucket screwed on tight and so the system is sucking air so it’s all out of whack and will not work right.

-- An Index Of My Model making Blogs

View TysonK's profile


154 posts in 2651 days

#4 posted 08-29-2016 12:49 AM

Thanks all.

As far as I know, checked it several times and couldn’t find any leaks. The top is was screwed down over a layer of silicone caulk, all the seams were caulked, I don’t think there are leaks.

The distance the pipe extends down was a guess, and I could only find info from Bill Pentz site as to how far it should be, but his cyclone looks much different. Here is a diagram of how it looks now, very well could be that the distance needs to be different, but not sure.

-- -- Tyson

View JBrow's profile


1368 posts in 1769 days

#5 posted 08-29-2016 02:43 AM


In January 1994, ShopNotes Volume 3 Issue 13 published a how to build you own cyclone dust collector article. The article is short on theory, but provided enough detail that I was able to build this cyclone unit. It worked amazingly well. If you are interested in getting a copy of the magazine, it was published by Woodsmith, Des Moines, IA. You may be able to get it by ordering from Woodsmith on-line or maybe a local library would have this issue.

Here are some dimensions from the ShopNotes article that could be compared to your cyclone and which may be helpful. The cylinder has a diameter of 16” and a height of 20”. The large diameter of the funnel is 16” and the small diameter is 6”. The funnel is about 18” high. The end of the internal pipe in the center of the cylinder and leading to the impeller is positioned about 1” above the seam where the cylinder and the funnel meet. The center of the 4” inlet pipe spec’ed in ShopNotes was about 4” below the top of the cylinder.

Some areas that might improve separation, if they can be addressed, are…

In your diagram, the internal 6” pipe connected to the impeller is slightly below the transition of the cylinder to the funnel. This pipe may be a little too long. But if the end of the 6” internal pipe is not low enough (i.e. too short), debris my just get pulled directly into the internal pipe, as suggested by WhyMe. This may require extending the height of the cylinder and moving the inlet up.

You mentioned the interior of the cyclone body is coated to make it smooth. If the coating applied to the wood does not eliminate the inside corners of the staves then these corners could introduce turbulence near the walls of the cyclone body. This disruption of air flow along the walls of the cyclone may be enough to allow debris to enter the low pressure zone in the center of the cyclone body and enter the filter. At this point it is difficult to see a practical way to eliminate inside corners.

You made mention that the unit is sealed to prevent air leaks. However, your photo shows a piece of MDF setting atop of the white dust collection bin. If this joint to the dust bin is not sealed and air is being pulled into the dust collection bin at this joint, some loss in efficiency could result.

View clin's profile


1121 posts in 1845 days

#6 posted 08-29-2016 03:17 AM

Bill has a detailed plan here, if this is something you hadn’t seen:

He has developed a spreadsheet where you enter some things like inlet size and blower power and it gives you the dimensions you need.

I didn’t study it in detail, but the spreadsheet is interactive and even changes the dimensions on the drawing (which is a cool Excel spreadsheet trick I’ve never seen before).

I put in 2 HP and 6” inlet and it seems to be a design VERY much taller than yours. The upper cylinder is about 28”, the cone is about 40” (68” tall total not counting blower or waste can), and the inside cylinder is about 22” long.

Oddly, it looks like the cyclone gets shorter with a high power blower. Maybe that’s because the air speed is higher and it doesn’t need to be as tall.

Again, I just played with it briefly and there are likely details I overlooked.

I think the spreadsheet allows you to force some dimensions, and it will then optimize the others, though this wouldn’t be an optimum design overall. Just the optimum for the dimensions you forced it to use.

I applaud your efforts in building your own.

-- Clin

View Fred Hargis's profile

Fred Hargis

6419 posts in 3342 days

#7 posted 08-29-2016 11:57 AM

I can’t help with the current woes, though it certainly sounds like a leak in the dust bin needs to be completely ruled out. Even the can itself may have a small hole that would cause that. I built one form the plans published in Wood magazine quite some years ago, and though it wasn’t perfect, it did as good a job as the Oneida I now have. Should you decide to go at again, a look at their plans may be useful.

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

View TysonK's profile


154 posts in 2651 days

#8 posted 08-29-2016 03:56 PM

Thanks JBrow, I will look for that article but your dimensions are certainly helpful as a comparison. I wonder if this version I’ve created is too large for the blower I have, at least width/ height ratio.

The inside was coated with a thick layer of durhams water putty to eliminate the segmentation of the staves, so it’s not as smooth as being made from metal or plastic, but it’s fairly smooth.

Thanks clin, I have looked at the spreadsheet from Bill and it’s really helpful. I build a wooden version based on his recommendations but ultimately scrapped that version in hopes this one would still work well enough. I’ll always be curious how well they would work in comparison to each other, but not going through the headache to build and put it all together to find out. Thanks again for recommending the spreadsheet though.

Thanks Fred, good to know that you were successful in building a version yourself, seems it is a viable option. Why did you opt to go with the Oneida? Just hopeful it would be better?

-- -- Tyson

View Fred Hargis's profile

Fred Hargis

6419 posts in 3342 days

#9 posted 08-29-2016 06:40 PM

Actually, I went with the Oneida to get a smaller footprint…seems silly, know. I’ve also formed the opinion that the Oneida stuff is chit, and now wish i had got a CV. Anyway, the way my shop built unit was set up had the cyclone on the wall with a 55 gallon dust bin under it. Then the DC I had at the time was sitting on the floor right next to it, pretty much the way it came (Penn State 2 1/2 HP with bag filters). I had piped the DC to the top of the cyclone with 6” snap lock…I did it this way because my motor/blower was way oversized for the Wood design and hanging it above the cyclone wouldn’t have allowed me to use the 55 gallon drum I had. I wish I had some pics of the setup, but as I said that was quite some years ago and I sold the whole thing when I bought the Oneida.

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

View Bill7255's profile


428 posts in 3133 days

#10 posted 08-29-2016 08:26 PM

Agree looks like there is a leak in the system. I thought about building my own cyclone, I ended up buying the one off eBay, $250 shipped. It looks to have different proportions than what you built. I have a 3hp (from Jet 1900) and used that. The cyclone works extremely well. Very, very little dust gets by from my drum sander. I am fortunate to be able to vent outside, but would guess I could go 6+ months if I had a filter. There is no visable dust outside bu the vent.

-- Bill R

View TysonK's profile


154 posts in 2651 days

#11 posted 08-29-2016 09:03 PM

Fred, a smaller footprint is always a valid rational in my book. With a garage shop space is at a premium for sure. That’s part of the reason I didn’t complete the tall Bill Pentz version of the cyclone, but regardless, good to know the Oneida works well as that’s what I’m leaning toward, just getting the Dust Deputy, skip the headache and get back to woodworking.

Bill, nice setup, and great to hear that it works well even for your drum sander, which I’ve wondered as to how effective any system would be on drum sanding.

Thanks all! I so very much appreciate all the suggestions. Likely I will just simplify and get an Oneida SDD. It would be too much trouble I think to try and re-build with a smaller diameter, which it probably needs based on the suggestions, but the SDD should fit fairly easily in that space.

Thanks again!

-- -- Tyson

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