# Building a Thien Cyclone garbage can separator



## beelzerob

As part of the Christmas gift-making post-mortem, it's time for upgrades to our dust collection system. One of the first was to get a cyclone type separator. I'm notoriously cheap (usually to my detriment), so why buy when I can make one! The most interesting and seemingly workable was the Thien Cyclone Separator. Looking over the pics and reading and re-reading the plans, I decided it was within my capabilities.

However, since there is not a pictorial how-to on making one of those, I decided to fill the gap and maybe accidentally be of use to someone. I am the ultimate "If he can do it, then so can I!" example, so if you feel like making a cyclone for yourself, have at it!

I'm not going to get into the nitty gritty details as far as trash can diameter and stuff like that...I think the Thien plans do a good job there. So mainly I'm just going to describe _how_ I implemented the plan.

Start off with the top of the lid. I was about to use MDF, but then I found a spare piece of pretty ugly plywood laying in the shop which was large enough, so I used that.








I used a drawing compass to get the shape and rough cut it with a jigsaw, making sure I was cutting outside the line (so the circle was too big). I then drilled a small hole in the center where the drawing compass had been and drove a nail through it so that the pointy end was sticking through maybe 1/2".

The reason for that was so that I could do the rest of the shaping with the router. I don't have a circle jig of any kind, so I had to improvise. Fortunately I have a small router table (sitting on my worktable), and I thought there must be some way to fix a rotate point for the center of the circle so that the edge of the circle hits the router bit. I needed a distance of something like 9" away from the router bit, and strongly supported. I realized I could make something to rest on the work table and then just clamp it to the router table so that everything was well supported and not moving. Some spare 2 X 4's did the trick. I drilled out a hole in the end for the nail to fit into snuggly.









This worked out incredibly well because the idea was to sneak up on the edge I was looking for, not only to make the outer edge of the lid (and baffle) but also for the rabbet on the lid. These adjustments were easily accomplished by sliding the 2X4 along the front edge of the router table to get the desired distance from nail hole to router bit edge.

This is me setting up the baffle for rounding.









Once the lid and baffle are cut and rounded, then I put the rabbet in the lid using the same router circle setup. I started with the router bit barely above the table top and only taking off a small amount. Then I'd remove the lid and fit it on the trash can. Once the lid set flat and snug, I knew I had reached the desired rabbet width. So I'd leave the circle jig at that distance and just make successive cuts with the router, slowly raising the bit, until I had a rabbet about 3/8" deep. That gave me a very snug fitting lid.

Here is the lid with rabbet and the baffle (with the nail still in it) stacked on each other.









(to be continued)


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## beelzerob

*(NOTE: I just realized an even easier way to do the remaining steps. Read through this so you know what I'm talking about, and I'll post the easier way at the bottom)*
Now that the lid and baffle were cut out, and the nail was still in the baffle, it was the perfect time to drill holes for the 3 supports the Thien design calls for. The nail in the baffle fit into the nail hole in the lid, so they were all perfectly aligned. Clamp them together, mark your 3 locations, and drill away.









Before unclamping, I highly recommend making a mark on the lid and baffle so that they can be re-aligned again. It comes in handy, as no matter how much you've tried, the 3 support holes you drilled probably only line up one way.









To evenly space the 3 supports, I took some flexible ribbon I had laying around, wrapped it around the baffle edge and them measured the ribbon. For me, it was almost exactly 60". Divide that by 3 and on the ribbon, put a mark at the 3rds (so, at 20" and 40"). Now wrap the ribbon around the edge again and just make a simple mark on the template where the start of ribbon is, 1/3 around, and 2/3 around. That divides your circle into 120 degree sections. So take a straight edge and measure out from the center nail hole to the mark on the edge and thats where your support hole will go. Also, keep the ribbon around because you'll need it again when it's time to cut the section out of the baffle.

Next it was time to cut the holes for the inlet and outlet pipes in the lid. I just traced around the street corner and used the jigsaw to cut as close to the circle as I could, making sure I was leaving it just a little small. That way I could use a sanding disc on my hand drill to slowly make it wide enough for the pipe, ensuring a very snug fit. This worked very well and the friction fit was nice and tight.









Now it was time to cut the 240 deg arc in the baffle. From what I could tell in the pictures, it seemed like the opening of the street corner should be about halfway on the 120 section of the baffle that was not removed. In order to know where the opening on the street corner was going to be on the baffle below I took a block of wood and placed it against the street corner (with it friction fit into the lid) and drew a line to the edge.









Now, re-stacking the baffle on top of the lid, I could see where the mark was on the lid and transfer that to the baffle...I now knew where on the baffle the street corner opening would be. (Note: Since the middle of the lid had been cut, the nail hole was no longer there, so to align the baffle and the lid, just put the threaded rod through the 3 support holes you drilled)


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## beelzerob

Heres what I MEANT to do: Take the baffle and lay the flexible ribbon around the edge, the one that still had the 1/3, 2/3 marks on it. Move the ribbon around so that the street corner opening is in the middle of a 120 degree section, and then marked where the other 120 sections are on the baffle. You should now have 3 marks on the edge of the baffle, one for each 120 degree arc, and the opening to the street corner should be in the middle of one of those sections. Lay a ruler along the center hole of the baffle and line it up with the mark on the edge to the right of the street corner opening. Draw a line from the edge towards the center 1 1/4" long. Now do the same with the mark to the left of the street corner opening. Use your drawing compass to complete the arc.

Heres what I DID: Turns out the opening to the street corner was conveniently in the middle of 2 of the supports. Since I already knew the supports were spaced at 120 degrees, I had everything I needed. So I just lined up the center hole with a support rod and drew my lines. Use the drawing compass to complete the arc.

In this pic I've already drawn the arc, but you can see how I lined up the center hole and the support to put my line on the edge. The mark on the bottom of the circle is where the street corner opens, and you can see how it will end up in the middle of the section that *isn't* cut away.









Some rough cutting and then cleaning up on the router table again, and I have my 240 deg cut out on the baffle.









Now it was time to assemble. I can put the middle pipe section in at any time, but obviously the street corner had to be in place first. I didn't glue it at this point because I wanted to make sure everything fit together.









I think what made me so happy about this particular project is how much stuff I had on hand that I could use. The 1/4" threaded rod was left over from a previous jig, and was the PERFECT size to cut into 3 pieces. The PVC pipe was just left over laying around and I had no plans for, so by using that I didn't have to worry about all the extra hardware that the thien plans call for. To cut the PVC spacer pieces, I just measured from the lid to the bottom edge of the street corner so that it would be just resting on the baffle.

The rough fitting looks pretty good.









Now, you may notice some things. First, I sunk in the nuts and washers in the top of the lid. The reason for that is because while the threaded rod was *exactly* what I needed for length...it wasn't what I needed for ASSEMBLY. I am using lock nuts on both ends of the rod. The first nut is easy to put on, just grab the center of the rod with pliers and tighten the nut. Then place the washer on the rod and insert it through the baffle and the PVC spacer and through the lid. Put the next washer on and then the last lock nut. There's the problem though...I left myself no threaded rod to hold so that I could tighten the last lock nut. If I put pliers in the bottom lock nut and tried to tighten the top one, it just pulled the bottom lock nut in further. So, to give myself some working room, I just drilled a hole big enough for the washer and nut on the top. That allowed me to grab the end of the threaded rod with pliers so I could tighten the 2nd lock nut well enough.

The other thing you might notice is that the street corner is facing the opposite direction of the one in the Thien plans. Ahh, the trap of assembling something upside down! Unfortunately, if I swing the street corner the other way no, the opening will no longer be in the middle of the 120 deg section. I would have to remove the whole assembly, reclamp the baffle to the lid, and redrill holes.

After doing some research, flushing, and then doing research _online_, I came to the conclusion that it would not be a catastrophe. The Coriolis forces involved are negligible compared to the force of the wind and mass moving...so though I created a backwards cyclone, it should be ok (NOTE: That makes this how-to guide perfect for you southern-hemisphere folks though!)


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## beelzerob

Well, I was confident enough in it to make the ultimate move...GLUE! I hate glueing. It's like the final exam in your work. 

I placed the middle pipe in and then grabbed the hot glue gun. This worked perfect, since even with the tight fit there was still gaps around the pipe. So I just went around the top of each pipe, glueing/filling as I went. I then tried to hit all of the area around the pipes in the middle as I could. If I'd *really* cared, I could have removed the nuts from the lid so I could take the 2 sections apart and glue all the way around both pipes on both sides of the lid...but meh. The fit was tight and the seal around the pipe on the top of the lid was good enough.

I bought some simple handles at the surplus store, so I decided where to put those. I placed them so that they were directly above the handles on the garbage can so I could use a bungie to hold the lid onto the can.









Easy to pick up and insert/remove from the can. Not bad. Now it was finally time for the test!

I connected the DC (an older 1 HP Jet) to the center pipe and cranked it up. I grabbed a handful of sawdust and heard the awesome sound of stuff hitting the bottom of the can. I then took a small stick and broke pieces off and fed them in. Once again, nothing but can. And that is the REAL reason I wanted to do this in the first place....not because of the ease of dumping sawdust, because we hardly make much of that. But mainly just to prevent some large chip from hitting the fan blades.

Once I was done playing with it, I dumped out the contents.









A good variety of sizes. No real dust that I could see, but lots of smaller pieces. (Since using the can, I have noticed some pretty fine dust in the bottom, so it *is* picking that up too).

So, that's how I put it together. About the only thing left I want to do, besides the bungies to hold the lid down, is to get some of that thin rubbery hose insulation Lowes sells and put that along the rim of the trash can. I think that will give a great seal.

Any questions, ask away. I'm by no means an expert on these things, but I'm an expert on how *I* did it. :thumbsup:

*EDIT: The easier way....*

You can save yourself a little bit of hassle if you rearrange the order you do some things. It comes from the fact that the supports are in a 120 arc configuration, and if you make that match up with the arc you need to cut out, then it becomes easier for you. That's essentially what I did, but I did it by accident.

So, do it in this order (picking up from the point when you were going to drill the holes for the 3 supports in post #2):
1) Mark and drill the hole for the street corner on the lid.
2) Fit the street corner and mark with the sharpie on the lid where the opening is (pictured post #2)
3) Remove the street corner and fit the baffle with the nail onto the lid again (it'll fit because the nail hole is still in the lid)
4) Take the tape and wrap it around the baffle, marking off the 120 locations.
5) Take a straight edge and draw a line all the way from the center hole to the 120 tick marks on the edge of the baffle, so you've essentially divided up the baffle into 3 equal sections.
6) Mark an equal distance from the edge on each line for the point where the hole will be drilled for the support.
7) Now rotate the baffle around until the opening for the street corner (marked on the lid) is in the center of 2 of the 120 deg lines. 
8) Clamp the lid and baffle together and NOW drill the 3 support holes.
9) Mark and drill the center hole in the lid, and continue....

If you look at the first picture in post 3, you'll see that this is essentially what I did, but again, it was just kind of lucky for me that it ended up that way.

Anyway, if it makes sense or is easier, then go for it.


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## ACP

Nicely done. I also built one of these and it was the best decision I could have made for the DC in my shop. Saves a lot of wear and tear, bags, and emptying time is next to nothing. Nice pictorial.


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## Ledhead

Very nice write up and use of pictures. Thank you for sharing with us. :thumbsup:

You used 4" pipe fittings. Do you think this design would also work using 6" pipe fittings? I don't see why it wouldn't. With 6" pipe would the 240 degree arc still be 1 1/4" from the edge? 
You also mention in your post #3 that the street corner is facing the wrong direction. I'm assuming that to correct the situation, you would have to relocate the 4" hole for the street corner so it aims the other direction but still have it dump out in the middle of the 120 degree arc.


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## beelzerob

The Thien writeup I think says that it should work for 6" too. I'd almost wonder if two 6" holes would fit on that lid though...that would begin to get tight. If so, just find a bigger trash can!

Keep in mind, facing the "wrong way" is just in relation to the Thien picture. I've since looked at other cyclone separators, and ya, they all seem to have the same entry design....but doing some simple research on the coriolis effect (what makes things want to rotate around low pressure) seemed to indicate it *really* wouldn't be a factor. However, if I did want to switch the direction, the easiest way would be to undo the three threaded rods, turn the street corner around, and then reorient the baffle so that the entrance is once again in the middle of the 120 deg section. Then just drill 3 new holes in the baffle for the threaded rods and reattach. That is going to be a lot easier and less destructive than trying to cut a new hole for the street corner (that would mean a whole new lid). It doesn't matter if there are multiple small holes in the baffle...thats not going to affect anything.


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## awoodman

Do you notice any build up of debree on the shelf, or does it remain clean?
I guess a Plexiglas lid or window would be an interesting feature to see what goes on inside...


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## beelzerob

Heh, that would be interesting....Theres not a lot of forces on the lid, as long as the hoses connected to the pipes aren't pulling to a side so I think a thick enough piece of plexiglass could handle it...it would be something to see the cyclone action. Hmmmm...

I didn't put a LOT of material down in my first test, but I did carefully raise the lid after it was done so-as to inspect the baffle for any material, and I did not see *any* sitting on the shelf. In a month or so I'll check it again to see. Or I may just take what's currently in my DC's bag and push that through to see the difference it makes....why not?


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## awoodman

Their is enough space on the lid to cut a small hole and screw on a pc. of plexi for a small window.


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## ACP

I have been using this setup for awhile now. There is nothing on the shelf until you get too full with the can. But it still continues to work at that point but some starts going into the DC bag. I just grab the handle every now and then and check the weight. If it's heavy I pop the top and take a look. Also if you see dust starting to go into the bag it's time for an emptying.


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## duncsuss

Good job and excellent write-up :thumbsup:



beelzerob said:


> ... However, if I did want to switch the direction, the easiest way would be ...


If your 3 support-rod holes are evenly spaced around the center, you could simply flip the baffle (top for bottom) along the diameter formed by the end of the corner-pipe and the opposite support rod ...


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## Texas Sawduster

*Nice work*

Nice work on the write up on your project.
Inspires me to take one of the two squirrle cage fans I have and get to work. :thumbsup::thumbsup:


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## beelzerob

Heh...ya, you could almost hook anything up to produce the suction, since it should be pretty protected from large chips.

I just picked up a 45deg dust collector fitting from Woodcraft that I think I'm going to place over the street 90 on the lid. That should give me something less than a hard 90 turn going into the top.


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## Texas Sawduster

*Old Vacume*

I have been holding on to an old vacume cleaner from years ago.
The brush is now brushless but the suction is still good. I am planning on adding it to the router table I built. 
One of these days.:laughing:


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## beelzerob

Well, I finally gave it a good test...face jointing about 6 different boards. I'm *very* pleased with it. I went and checked the garbage can and there was about 4-6" of material down there. I hadn't emptied the bag yet, so I don't know how much actually went into the bag instead of the can. But at the very least, from an "ease of emptying" perspective, this is great.

On a side note, since I was jointing orange osage, cedar, cherry, and some red oak, the stuff in the bottom of the can was *very* pretty. 

I have an insufferable need to tweak, and I'm looking at that 90 deg street corner on the top. I bought a 45 deg DC fitting that I can put on the lid, but if I don't replace the street corner with a 45 deg section, then it's kinda moot. Unfortunately, the way everything is laid out currently, I just don't see how I can put that 45 on the lid without having to completely redo the lid. *shrug* I think at this point I'm going to leave it alone. If I can find another scrap piece of 3/4" plywood then I may try a brand new one, so I've got this first one as a fallback.


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## BWSmith

beel,good on you for making.......vs buying.

I had a brain f*rt this w/end whilst building a roughly 18"HX14"DX16"Long,enclosure for bullet casting pot.Doing the sheetmetal plenum and attendant duct(enclosed fan unit)got me to thinking DC in woodshop.

Whatif you could come up with a simple baffle'esque arrangment with,or in duct......... which is "plumbed" over an appropriatly sized sq'ish ply bx that sits on fl under a DC vert duct.The duct from tool enters the vert @45*.The leg of wye that goes down would dump into top of collection bx.Any chips that landed in bx(because of enclosed baffle)would be that many less going to main unit?The baffle is a simple redirect of dust/chip flow.The heavier particles fallout of airflow after hitting baffle.Lessoning load or weight of air/chip in any further travel.The coll. bx shape can be whatever suits,sq,rect,tallish,skinny,cardbd,plywd,ect,ect.Since it dosen't have direct bearing on whats happening above it,don't matter what shape.Like I said,might be just a brain f*rt.BW


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## RetiredLE

Neat write up on a useful homemade tool. Space is at a premium in my shop so was wondering if this same system could be made out of a five gallon bucket.


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## beelzerob

And what, 2 1/2" hose? Well, the principles are all the same...I don't see why it wouldn't work. I know vacuums work on a bit of a different principle than dust collectors (pressure vs. airflow, or something like that), but I've seen these little cyclones for vacuums too, so I guess it's good.


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## RetiredLE

beelzerob said:


> And what, 2 1/2" hose? Well, the principles are all the same...I don't see why it wouldn't work. I know vacuums work on a bit of a different principle than dust collectors (pressure vs. airflow, or something like that), but I've seen these little cyclones for vacuums too, so I guess it's good.


I was thinking of using the same diameter fittings as what comes on the typical router table, rotary sander setup.


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## twocreeks

*4" street fittings*

Since I am also very frugal, I would like to use the aluminum 4"
elbows I have. They also can be rotated to make a gentler angle
which I understand is preferred in dust collection.
Since researching the dust separation topic I've a # of designs.
So would it work to simply use the metal lid that comes with can,
make sure it seals onto the can, and insert the elbows w/o the baffle OR add a baffle to the garbage can lid?

Hope I'm not asking too much.


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## m.n.j.chell

Reviving another old thread to ask a question ...

I am preparing to build a cyclone dust collector. My question is, with a 33 gallon barrel as the collection reservoir, what's the smallest size shop vac I can use.
I was just given (Christmas) a (small?) 12 gallon (? it's at home, I am writing this at work) Shop Vac. I am wondering if I can use it, or do I need to buy a larger vacuum? 
I don't generate a LOT of sawdust, so if I buy a larger vacuum, I probably don't need to build the cyclone.

Kind of a "catch 22".


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## TomCT2

I use a 8 gal - I only collect chips in the can w/ cyclone from the planer. everything else goes direct into the 8 gal Shop Vac
my set up is in post #17 of
http://www.woodworkingtalk.com/f32/dust-collection-strategies-home-shop-130233/#post1446377


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## m.n.j.chell

Thanks for the link, Tom. Your write up was just what I was looking for.

I do believe I am ready to start the build. But it'll have to wait for a few weeks. Company is sending me to Hawaii for two weeks, to teach some people there.
It's a terrible job, but somebody has to do it !


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## Kerrys

From experience, don't use a cheap plastic can. They can't stand up to the vacuum and will collapse. Once it collapses it loses the cyclone effect and the dust won't settle to the bottom.


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## m.n.j.chell

First ... I was mistaken on the size of my shop vac. It's only a 5 gallon size.

Second ... I am going to use an industrial grade plastic barrel, not a plastic trash can. It's much thicker walled than a trash can.


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## Kerrys

mikechell said:


> First ... I was mistaken on the size of my shop vac. It's only a 5 gallon size.
> 
> Second ... I am going to use an industrial grade plastic barrel, not a plastic trash can. It's much thicker walled than a trash can.


Again from experience and I'm certainly not an expert, creating a system with no leaks is a must. I don't think the capacity of your vac is as important as how much air it moves. It must move enough air to create the cyclone effect. As long as you have a decent volume of air moving with no leaks it will work.


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## m.n.j.chell

Thank you, Kerrys.
I was thinking along the same lines. A dust separator, without any leaks, is basically the same as very long vacuum tube. 
I'll get around to building it, then I'll let everyone know if it works.


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## TomCT2

the suction from my ShopVac will "pop" the sides of the metal can inward if I block the suction end - even thick plastic may not work....


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## m.n.j.chell

Maybe not, Tom ... but it's free and I have it on hand. If it doesn't work, I won't be all that upset.


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## Alchymist

Have built several of the Thein style separators, but found the cyclone style is more effective. This one works the best of anything I've built thus far:

http://www.woodworkingtalk.com/f2/going-try-something-136162/


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## regesullivan

The problem with the first Thein style separator I built was the elbow dirtied up the air flow so much it caused a good bit of the dust to get sucked in instead of dropping below. Once I cleaned up the intake by going with a side intake and smoothing out as many rough spots as I could it was much better. The only obvious turbulence was where air slammed into the baffle at the start of the cut out slot as it traveled around the canister. I formed an upside down ramp and it cleaned up most to that. Not the best pictures but I hope it gets the point across.

I've emptied the barrel at least 15 times and there is still less than a cup of very fine wood flour in the plastic bag mostly from blowing out the filter.


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