Here's the plans.

[jgarner101351]

I am going to modify my HF dust collector based on the Thein baffle. I plan to exhaust my >5 micron dust outside via a dryer vent set up rather than using a cartridge filter. Has anyone done this and is there a problem with this as long as I knock out the big stuff (saw dust, wood chips, wood slivers etc.)? I don't want anything but 5 micron or smaller dust going through my DC impeller anyway. I was working on ways to do this and researching when I found the world of info on the Thein baffle and HF DC modifications. Thanks Phil and all you other folks that have used Phil's baffle design and so graciously shared your experience, photos, plans, materials lists and so forth.

[Dewa Designs]

You are close to right. Yes the center of the baffle is indeed the center of the lid, and yes it is over the center of the trash can, drum, or whatever your vessel is.

The elbow in question empties out at the start of the solid part, not the drop slot, or aperature as you called it, so that they loaded air is slightly deflected away from the shavings / dust below.

The slot / aperature is 1-1/8" wide. I do not know why Phil designed it this way, and if it needs to be adjusted for larger sizes. For my HF 2HP DC I made the drop slot 1-3/8" wide by sheer measurement mistake and it still worked fine. On the one I am building for the 55 gallon drum, 4" pre separator the drop slot will be 1.25" wide. Right or wrong that is how it will be made.

Hope this helps, and sorry about the slow reply. I didn't notice your post for the longest time...

Is there a "rule of thumb" for the size of the slot in the baffle?  I'm thinking that the area of the slot should be similar (larger?  smaller?) to the inlet or outlet area.  This information would help in scaling the design to other duct and drum sizes.  I expect that the angular dimension of the slot at 240 degrees is fixed so the only available variables are the slot width and the diameter of the drum.  Any comments and suggestions welcomed.

[BernardNaish]

The width of the slot is set to suit the material being handled. The narrower the slot the finer the material separated and the wider the slot the coarser it may be.

Clearly if you are separating wide long strips from a thicknesses then the gap needs to be wider - on the other hand if you are separating dust from a sander only then it needs to be narrower.

Note the start and end of the slot is critical straddling the inlet rectangle (pipe). So it ends just before the inlet and starts again on the other side so leaving a "platform" spanning the space under the rectangle. The leading edge of the slot needs to be tapered down so that big shavings don't catch on it.

I hope this helps and it would be good to hear how you get on.

[dbhost]

I am going to modify my HF dust collector based on the Thein baffle. I plan to exhaust my >5 micron dust outside via a dryer vent set up rather than using a cartridge filter. Has anyone done this and is there a problem with this as long as I knock out the big stuff (saw dust, wood chips, wood slivers etc.)? I don't want anything but 5 micron or smaller dust going through my DC impeller anyway. I was working on ways to do this and researching when I found the world of info on the Thein baffle and HF DC modifications. Thanks Phil and all you other folks that have used Phil's baffle design and so graciously shared your experience, photos, plans, materials lists and so forth.

The biggest problem aside from adding dangerous sized particles to the outside air and contaminating it (we are trying to clear the air right?) that I can see behind unfiltered outside venting is you will be moving heated or cooled air away from your workspace at 1K + CFM. You'll never be able to effectively heat or cool your shop making it, depending on your climate of course, a nasty, miserable place to work. I wouldn't (and didn't) go that route for just that reason.

[WayTooLate]

DB & JGarner -
If you are fortunate to live in a climate where you can work in your shop most of the year without heating or cooling, you are tempted to discharge outdoors.  Our primary task in dust collection/filtration is to keep the particles out of our lungs.  Overall environmental cleaning is a noble idea, but idealistic if not unreasonable.  Releasing 1 micron particles into the atmosphere is not considered by regulating agencies because its dispersal is so great that it becomes irrelevant.   We would be better off trying to regulate pollen and hay-fever sources because they are much more harmful to human lungs. 

However, dust concentrated within an indoor space, is extremely important - which is why our dialogue on this website continues. 

Since my primary concern is to keep those dust particles out of my (and my co-oworkers) lungs.  I am sometimes in situations where I cannot collect the dust and chips and fumes into my DC.  At those few times, I simply place a HEPA filter over a box fan and blow it from behind us across the dust source(s).  This keeps a supply of clean air for us to breather while the particultes are blown away.  Once the dust settles, we can remove our filter masks.  Later, we suck it up into a shop vac with a Thien separator installed.  All clean!

[Tengbrec]

Many Thien baffle enthusiasts have been searching for methods & modifications that might improve in the separation of fines/"wood flour".  In researching my own build, a possible solution has occurred to me:

In many pictures and videos of Thien separators—especially those that make use of transparent acrylic &/or polycarbonate—very fine sanding flour can be seen 'sticking' to the separator as a result of electrostatic forces.  This is hardly surprising, since high velocity particles rubbing against either of these materials is reminiscent of the static experiments many of us did in school, rubbing an acrylic rod with wool in order to demonstrate a negative static charge.

My idea is to exploit the electrostatic properties of these plastics in order to exaggerate this effect and remove a higher percentage of sanding fines during dust extraction.

This could be trialed very easily by temporarily fixing something like a wool buffing wheel to the EXTERIOR of the separator assembly, where it would create an initial negative static charge on the plastic surface.

Theoretically, this would result in MORE of the fines adhering to the inside of the plastic—in turn, creating a small amount of additional turbulence—which might further exaggerate the effect by slowing the cyclonic air path.

Of course, the fines wouldn't be expected to drop through the Thien baffle until the collector and 'static generator' is turned off, at which point the mass would drop under its own weight, or with a gentle tap.

If this worked, it might permit a more versatile dust collection solution, where a conventional Thien baffle is used for coarse material, and where the 'static generator' is employed on the exterior of the otherwise UNMODIFIED Thien separator during tasks like sanding, where a higher quantity of fines is expected. 

...Wondering if anyone might be in a position to test this concept properly?

Just a thought.  I am most grateful Phil's generous design offering and everyone else's contributions.

[dbird]

Has anyone tried to use the separator design to modify their shop vac directly? Seems like one could save a lot on filters if it was useful.

Yes, I realize that this is not the way a dust collector works usually.

But, I use my vac mostly as a vac. My shop area is small and I don't use it enough to rig up an actual dust collection system. Or, if I did, I'd just hook up the vac directly.

Any thoughts welcome.

Thanks,

Dave

[JimmyTheHand]

This should probably have been posted as a new thread, but I'm not able to create a new thread. Probably because I'm a new user on this forum.

I'm planning a build of the cyclone, but have had trouble locating a suitable trashcan. I've found no suitable trashcans in locally.

I had been thinking of using an empty oil barrel. But I guess those are a bit too heavy to move around for emptying.

I've now found the Brute trashcan online. As many people seem to use this trashcan, I have a question for you.

Can someone who has either the 55 gallon or 44 gallon version please measure the outside diameter of the trashcan?

I ask because I need to know the outside dimensions before ordering. I need to make sure it is smaller than the door opening to the room where my dust collector is.

I found the following info on the web, but it doesn't say if the measurements are taken on the inside or the outside:
55 gal  208.2 L
Diameter:   26.4 in     67.0 cm
Height:     33.2 in     84.3 cm
   
44 gal  166.6 L
Diameter:   24.0 in     61.0 cm
Height:     31.5 in     80.0 cm
                               
32 gal  121.1 L
Diameter:   21.9 in     55.7 cm
Height:     27.8 in     70.5 cm

The largest one will probably not fit through the door opening.  I hope the 44 gallon one will fit.

I'll build a 6" separator. I think both the 32, 44 and 55 gallon trashcans are large enough for this. I read, somewhere, that the minimum diameter should be inlet size * 3. For me that would be 6" * 3 = 18". All of the trashcans are larger than this (assuming the measurements are the inside diameters).

[deancrozon]

Can this be scaled up to 48 inch diameter with a twenty inch inlet, and still work ok?

[BW68]

My shop vac filter is pretty well caked too.... I use it primarily for cleaning the shop floor, and for my palm and RO sanders, so LOTS of fines get sucked up. I'm thinking a smaller diameter separator could help.

I switched to a 5 gal bucket for the separator section to keep the air velocity up.  So far it seems to work better,  But experience is limited,

[Ex-Tex]

These systems always run by applying a vacuum. Can anyone tell me if the reverse is applicable?
Can you run the powered exhaust from a DeWalt 735 thickness planer into this system?  With, or without using something like an enhanced Harbor Freight collector?

[WayTooLate]

Can this be scaled up to 48 inch diameter with a twenty inch inlet, and still work ok?

Dean -
I can't imagine why you haven't had many responses to your request!  ;)
If you browse through the posts about building a Separator, you will find that a 5hp system is huge among our builders.   :o
I have a very large one ahead of a 20hp bag house.  But it has a 14" duct and should have been scaled smaller to be more effective.  I can't calculate how much horsepower you would need to drive such an enormous air mass at a speed fast enough to create the centripedal force to pull clean air out without debris. 

If you have a system that is that big, I have two suggestions:  8) You need a professional engineer to get the benefit out of such a large system; Or, you need to make smaller subsystems closer to the source of your debris generation. 

Otherwise,  Good Luck!  :D

[Schreck]

These systems always run by applying a vacuum. Can anyone tell me if the reverse is applicable?
Can you run the powered exhaust from a DeWalt 735 thickness planer into this system?  With, or without using something like an enhanced Harbor Freight collector?

Yes!
Use the Search function and you will find at least one system for the Dewalt planer that does not use an external blower - just the planer's internal blower. Here is a good one:
http://www.jpthien.com/smf/index.php?topic=809.msg4539#msg4539

[rbucket51]

OK

Built my lid for a 32 gallon galvanized trash can.

Testing yielded the following:

10 gallon volume of  dust, shavings and chips in the can; 3 cups of dust in the plastic bag of my ShopFox...

Used a new bag and felt for the test. 4" Hoses.

Ran the following:

14" Bandsaw
10" Cabinet saw
13" Planer
Router Table
8" Jointer

Handled everything perfectly.

[rosenw]

I have a Harbor Freight dust collection system that I wish to modify with a Thien baffle.  I plan on using a 31 gallon galvanized garbage can for the dust collection system using the lid with holes cut into it to fit the inlet and outlet.  My question is should there be a distance between the bottom of the inlet elbow to the baffle or should it be resting on the baffle.  It would seem there should be separation from the bottom of the elbow inlet to the baffle to allow air to circulate around/below it.  Thanks.