Dual Thien Baffle idea

[Peter Aeschliman]

Hello all,

This is my first post here, so please go easy on me!! :-)

I'm fairly new to woodworking, and I'm working on redoing my DC system. I just purchased a 3hp Grizzly DC that I plan on converting using a Thien baffle. I plan to vent the exhaust and fine dust through the wall of my shop to the outside to avoid dealing with filters.

This is what my grizzly unit looks like:

http://i66.photobucket.com/albums/h255/peteraeschliman/g1030.jpg

I would like to do something similar to what Angie Orfanedes did in the following thread, where I use the drum(s) from the original DC setup as a housing for the Thien Baffle.

http://www.sawmillcreek.org/showthread.php?t=109166

As I got to thinking, the thought occurred to me: What if I just assemble the DC just like it's intended to be out of the box, except replace the top bags with top baffles with a pipe coming out of the center for the fine dust exhaust (just like the top of the thien baffle), put the Thien Baffle inside the drums like Angie did, and put metal garbage cans on the bottoms? In other words, there would be two thien baffles, two garbage cans, and two exhausts.

It seems like way less work to me. The two things about this idea worry me, but I need your input:

1) As you can see in Angie's setup, the blower is on the exhaust side of the unit. Said differently, the dust is pulled through the Thien baffle aparatus first, and then the fine dust goes through the impeller and out the exhaust. My idea calls for all chips and dust to go through the impeller first, and then get pushed through the thien baffle. I don't know if this will cause any issues. I can't think of how it could, so please help me think that through.

2) I would have two baffles to push the dust through (one on each side of the DC). I wonder if this will cause too much static pressure loss. I also wonder whether it's just the opposite- that it will decrease static pressure loss in comparison to a single-baffle setup since the air is flowing more freely. Said differently, one of the advantages of a 4-bag setup vs a 2 bag setup is that there is more filter bag surface area, which increases air flow...

Please set me straight here. If you guys think this will work, I will go for it and report back. If you have lots of reservations, I will just do a setup like Angie's with one baffle and with the blower on the exhaust side of the baffle.

Thanks in advance!

Peter

[Phil Thien]

You can do it.

First of all, the baffles will introduce little static/cfm loss. Much less than a bag (loaded or otherwise). So go ahead, and add a baffle to each side and a top plate with an exhaust outside.

Second, the garbage cans are going to be a challenge because of the rigid duct coming from the blower. Further complicating matters is the fact that you have TWO rings, so getting them to sit on garbage cans w/o creating leaks is going to be tricky.

Finally, having all the debris go through the blower first isn't a problem as long as you don't pickup metal (which can spark) or large pieces that will jam the works.

So it can be done but I think the only challenge is getting everything sitting on two garbage cans. If you just used two bags it would be easy.

[Peter Aeschliman]

Wow, the man himself!

Thanks so much for your reply. Something you said made me have a "DUH" moment:

"So it can be done but I think the only challenge is getting everything sitting on two garbage cans. If you just used two bags it would be easy."

DUH. I don't need to use garbage cans. Don't know why I assumed that. I will need to order some clear plastic bags since mine comes with the 30 micron ones. I don't want the bags to act as filters, especially if they're only 30 microns.

Now here's another question. Phil, hopefully you don't find this insulting!! I'm just trying to make sure I don't do more work than I need to. My question is, do I need a Thien baffle? The design of what I'm calling the "drum", and what grizzly calls the "collector" is as follows:

http://i66.photobucket.com/albums/h255/peteraeschliman/untitled-1.jpg

You can see that the inlet is below an inverted, funnel-shaped flange that runs around the inside of the "drum." The manual says that this helps create a cyclonic current, which I assume separates the fine dust from the heavier stuff. Do you think this will do good enough of a job separating fine dust (which, remember will be blown outside rather than through filters)?

I don't see why I can't still add a Thien baffle to the bottom of the thing still. But I personally get more enjoyment out of using my tools rather than working on them! So I'd like to avoid unnecessary work.

By the way, thanks Phil. I hope you realize how much money you have saved guys like me with your incredible invention. I really appreciate it.

[Angie Orfanedes]

Peter, are you sure you want your rig to be so complicated? I think the primo advantage of exhausting to the outside world, is never having to mess with any bags. I don't understand the advantage of using two collectors - it seems to me that the airflow is still limited by the inlet size of the impeller - that is, I don't think the airflow would be improved with multiple bags, but I might stand to be corrected on this. So I would still recommend a setup like mine:
118567


The Thien separator sits at the bottom of the collector (under the inlet) attached to three one inch dowels spaced 120 degrees apart, that also attach to the "inverted funnel" of the collector. Phil's website has pictures of a Jet DC modified this way.

The airflow with dust and chips comes in on top of the Thien separator (baffle), swirls around and drops down into the can with only the super fines coming through the impeller and out of the exhaust - the exhaust rarely has visible particles. So the Thien separator (baffles) works very well - thanks, again, Phil.

The final evolution of my Green Monster looks like this:
118566

The can seals into a groove (cut with a router) cut into the plywood top - as does the collector. So if you have a router, and a piece of plywood to use for a compass, cutting the groove is easy.

Then again, I really like to see other people's ideas of DC rearrangements. So, keep us up to date on your progress.

[Phil Thien]

Wow, the man himself!

That's hilarious.



My question is, do I need a Thien baffle?

In a word, yes. The design of your ring is very typical of single stage DC's. And yes, it will absolutely spin the debris into a vortex.

However, the giant hole in the middle of the ring will act as a chimney, allowing debris in the bottom bag, activated by the incoming airstream, to lift into the filter stage or (in your case) just exhaust via the exhaust pipe.

As long as the DC's blower is running, it will be churning that debris in the bottom bag and sending stuff through the chimney.

That is what the baffle prevents. It focuses the energy of the incoming airstream, using that energy to provide maximum separation. Then, it blocks already separated media from re-entering the airstream and making an escape via the chimney.


By the way, thanks Phil. I hope you realize how much money you have saved guys like me with your incredible invention. I really appreciate it.

At the same time I've been blessed with the fortune of speaking to woodworkers from all walks of life, on every continent, that are putting the baffle to work and sending me pics (E-Mail and snail mail) of their completed systems.

In the final analysis, I think I'm getting more out of this than you guys. :D

[Peter Aeschliman]

Thanks for the input guys.

Angie, I think the setup I'm considering sounds more complicated initially, but the reason I'm going this direction is actually because I think it's less complicated.

I don't have to come up with a plywood rack like you have (love your setup btw). I don't have to figure out how to make a round pipe join up with the square connections of the collector drum and the impeller/motor housing. And I don't have to come up with a way to connect a metal garbage can.

All I need to do is get some clear plastic bags for the bottoms, build the thien baffles exactly as you did, and connect the exhaust to the wall. So my aparatus will be bulkier than yours, but ultimately, the construction will be much simpler since I'm relying on the original design and components as much as possible. The other advantage of this setup is that I will be able to go longer without emptying the bags since I will have two of them.

So in general, I'm trying to be as lazy as possible!! :-)

Phil, you're right about the baffles. It's not a whole lot of extra work at all, and I only want the super fine dust going outside. So it makes sense.

I'm glad you get so much pleasure out of your design. You probably wouldn't enjoy it so much if you had done what most people would've done and gotten a patent and opened up a new store!

I'm going to build this thing sometime in the next few weeks and I'll take progress pics.

Thanks for everyone's input.

Peter

[Phil Thien]

You probably wouldn't enjoy it so much if you had done what most people would've done and gotten a patent and opened up a new store!

In the interest of full disclosure, I am patenting it. But I don't mind people making their own (for personal use), either. I'm not trying to get rich or anything.

[Jon Crowley]

Angie - what size PVC are you using that fits perfectly to the stock center ring?

[Angie Orfanedes]

I used 4 inch S&D PVC throughout. For my connector inlet, I used the stock piece which came with the DC - which was supposed to be 5 inch i.d., but it was really much smaller. I then glued in a piece of the 4 inch PVC about six inches long with another ring of 4 inch PVC over it - I cut a slit in the "over" piece so it would slip over the first piece. This adapted the undersized 5 inch inlet to be a standard 4 inch PVC inlet that fit right into a long sweep elbow. Then I used caulk to make it airtight. Hope this explanation is understandable.

[Peter Aeschliman]

In the interest of full disclosure, I am patenting it. But I don't mind people making their own (for personal use), either. I'm not trying to get rich or anything.

Can't blame you for that, man. It's your right to make some money from your very useful invention! There's great demand out there for something that works better than the trash can lids sold by the retailers but is less expensive than a cyclone. You'd probably only have to make a few models- one for the Shopvac/bucket setup with properly sized hose connections, and a few other sizes for full-sized single stage DC's (with 4", 5", and 6" duct sizes). I can't imagine that wouldn't sell, especially if you could get distribution with Rockler and Woodcraft.

I have started building my baffle. I'm not too far along- I've just routed the top baffle pieces with the groove to get a good seal. I can't cut the hole in it until I buy my ducting (6" pvc S&D) and have the proper dimensions. This should be pretty straight forward, really. I'll post pics soon.

Thanks for your help everyone.

[Peter Aeschliman]

Phil,

I have another question for you if you don't mind. I have searched your forum and have not found an answer. Since I am using a 6" inlet and 6" outlet, and the diameter of the "drum" or separator section pictured above is around 19", what considerations do I need to make on scaling the baffle?

Your site says that you made the 240 degree recess (where the diameter of the baffle is smaller) 1.125". Does the size of this recess need to change when you scale your design up to larger sizes?

I saw this question posed on your site a few times but I couldn't see where anybody answered it. Intuitively, I would think the recess needs to be greater than 1.125". But another part of me says that since the drums are 19" in diameter, that factor alone increases the surface area of the baffle and therefore the space for chips to fall through that 1.125" cutout is increased as well.

Thanks again for your help.

Peter

[Scott Wigginton]

Peter, I'll give you another idea (which I'm currently considering for my PM75 which has a similar two ring/bag design).

Put the chip collection outside

I'm gonna remove the rings that support the bag structures and hookup PVC to the point where the "Rubber Gasket" is on your image. Then I'll duct it outside and into a chip bin.

[Phil Thien]

Intuitively, I would think the recess needs to be greater than 1.125". But another part of me says that since the drums are 19" in diameter, that factor alone increases the surface area of the baffle and therefore the space for chips to fall through that 1.125" cutout is increased as well.

Thanks again for your help.

Peter

The 1.125 is determined by the size and weight of the media being separated. For sawdust, 1.125 is plenty, and should accomodate even somewhat stringy shavings (from planing pine, for example).

No need to increase it unless you experience clogging. I've only had one or two reports of this and those guys were doing pretty much nothing but surfacing pine. It wasn't happening a lot for them. But if it happens once a week it is a PITA. And even then, increasing from 1.125 to 1.375 was all it took.

[Peter Aeschliman]

Peter, I'll give you another idea (which I'm currently considering for my PM75 which has a similar two ring/bag design).

Put the chip collection outside

I'm gonna remove the rings that support the bag structures and hookup PVC to the point where the "Rubber Gasket" is on your image. Then I'll duct it outside and into a chip bin.

Thanks Scott- I definitely did think about that. Unfortunately, I don't own my shop (my parents do) and I don't think they'd agree to me adding anything to the exterior of the structure. It was a stretch just to convince them to let me cut dryer vents into the walls!


The 1.125 is determined by the size and weight of the media being separated. For sawdust, 1.125 is plenty, and should accomodate even somewhat stringy shavings (from planing pine, for example).

No need to increase it unless you experience clogging. I've only had one or two reports of this and those guys were doing pretty much nothing but surfacing pine. It wasn't happening a lot for them. But if it happens once a week it is a PITA. And even then, increasing from 1.125 to 1.375 was all it took.

Gotcha. That makes sense. If that happens to me (doubt it will), I can just pull out the baffle and make the adjustment.

Can't wait to get this thing going. Unfortunately I only get 1 day/wk in my shop since it's remote, so it will be at least a few weeks before I can get all of my ducting in place... ugh!

[Rick Potter]

One last thought...

I had a 3HP Powermatic collector like yours. The bags do not have to be the expensive DC bags. I went to Lowes or HD, and got Contractor trash bags. Check both places, because one of them had heavier bags than the other. I just checked mine and they are 42 gallon, 3 mil thick contractor trash bags. They worked fine on my DC.

Rick Potter

[Nick Abbott]

Thanks Phil. I will be building my first Thien baffle next week.

[Peter Aeschliman]

Alright, so I decided not to vent outside at all. This cost me a lot more money, but I went with the 36" tall Wynn Environmental Poly spun bond .5 micron cartridge filters.

The reason is that I turned on my new DC without the ducting attached and realized that this thing really pulls a lot of air. I have been working hard on insulating and drywalling my shop for heat in the winters, and it would be really counterproductive of me to suck all of the warm air out of my shop like that. I definitely thought about this issue before, but I didn't really get how much air I would be blowing out of the shop until now!

I'll keep you guys posted. They have to make my filters and ship them to Seattle from PA, so I won't be getting them for at least a few weeks. I can still build the thien baffles without them though.

From what I've seen, my setup will be pretty unique. I'm excited to see how well it performs.

[Greg McCallister]

This is my version of Phil's baffle (http://www.sawmillcreek.org/showthread.php?t=97825). being that you have one heck of a blower - I would like to see what that would do on mine.
Good luck.

Edit- here is another mod (http://www.sawmillcreek.org/showthread.php?t=102563) I did after the first post.

[Peter Aeschliman]

Yeah, I saw those threads. Great work!

The only downside I see of my adaptation vs. yours is that all material passes through the impeller. I don't think this is a major problem since I use my shop vac to clean up the shop. My dust collector will only be hooked up to my tools.

I can't wait to get this thing hooked up and going! I'm working on the baffle tonight and tomorrow. Should be done tomorrow with the exception of the Wynn Environmental filters, which won't be here for a few weeks.

[George Bregar]

I know this is an old thread, but question pertains to it. I am contemplating installing a Thien seperator in front of a Grizz G1030Z2 DC http://www.grizzly.com/products/3-HP-Dust-Collector-with-New-Impeller/G1030Z2. My shop is in a converted three car garage at my lake home in northern WI, so although I would prefer to exhaust outside, I was thinking in the winter I would run it through the DC. My idea was to install blast gates on the output side as shown with red arrows in the picture attached. One side would have the bag replaced and 6" PVC to outside exhaust. The other side would have the upper bag replaced with a high performance filter. Opening/closing the blast gates would direct the output to either the bag/filter or outside. I don't think that this would degrade performance as the exhaust diameter is the same as each output in the "Y". Any thoughts?

Oh, it will be 6" in/out of the Thien and I will pull the triple connection to the DC and run 6" to it.

[Peter Aeschliman]

That's a really interesting idea! I wish I had thought of it.

Man, I might have to copy this somehow!

My thought (with no experience to back it up) is that you'd probably want to install more of a "flap" or "diverter" where the duct splits off, rather than installing two blast gates. I say this because although the air will follow the path of least resistance (meaning, through the open blast gate), you also have to consider the trajectory of dust as it comes out of the impeller... it will try to blow up into the closed off section of the duct, causing turbulence.

I'm no physicist, so I might be overestimating the issue... And this would definitely be more of a problem if you designed your DC like I did (with the separator AFTER the impeller inside the rings) because you'd be dealing with larger chips rather than fine dust.

Just a thought to consider.

[George Bregar]

My thought (with no experience to back it up) is that you'd probably want to install more of a "flap" or "diverter" where the duct splits off, rather than installing two blast gates. I say this because although the air will follow the path of least resistance (meaning, through the open blast gate), you also have to consider the trajectory of dust as it comes out of the impeller... it will try to blow up into the closed off section of the duct, causing turbulence. I actually had the same thoughts, hopefully someone can add to this. I think a flapper would be very difficult to engineer and make however. Wait...why not just have a 6" long sweep elbow that goes one way...or the other? Make the change in December, change it back in May?

Edit: Need something to hold the bag/filter, I think Sched 40 PVC would be okay. Just would need to fab a fitting to transition from the round PVC to square fitting.

[Dan Hintz]

In the interest of full disclosure, I am patenting it. But I don't mind people making their own (for personal use), either. I'm not trying to get rich or anything.
Phil,

I know it's an old thread, but since someone else brought it to the top...

When did you file the patent on this? I ask because if it was made public before the patent was filed, the patent is unlikely to hold up in court...

[George Bregar]

Phil,

I know it's an old thread, but since someone else brought it to the top...

When did you file the patent on this? I ask because if it was made public before the patent was filed, the patent is unlikely to hold up in court... Think it's actually a year before.

[Bob Riefer]

Working on a foggy memory from a patent class at work... but



if it was made public before the patent was filed, the patent is unlikely to hold up in court


I believe "prior art" is defined as public mention of an idea. Prior art can squash a secondary "inventor" from getting a patent granted on the primary inventor's idea (that is proven by the presence of prior art). So I do not think that Phil publicly mentioning an idea has bearing on Phil getting a patent - although it would have bearing on whether someone other than Phil could get a patent for his baffle design.

But I'm no expert, I'm just paraphrasing what we were taught by the attorneys at my company.

[Phil Thien]

According to my attorney, I had one year from public disclosure to file (which we did).

There are some compromises when you do it as I did. But there are some benefits which (for me) outweighed the compromises.

[George Bregar]

Ok, I was right about the one year, how about the design Phil? Will closing one of the "Y's" with a blastgate detriment the flow? :)

[Peter Aeschliman]

Wait...why not just have a 6" long sweep elbow that goes one way...or the other? Make the change in December, change it back in May?

The simplest solution is often the best one. If you're only going to be changing it over once or twice per year, I don't see any issue with doing it this way.

[Phil Thien]

Ok, I was right about the one year, how about the design Phil? Will closing one of the "Y's" with a blastgate detriment the flow? :)

Yep, but I doubt it would be enough to be consequential.

[George Bregar]

Yep, but I doubt it would be enough to be consequential. Yeah, thats what I thought...and thanks again for your design. It certainly has to have commercial appeal. Hope you do get rich!

[George Bregar]

The simplest solution is often the best one. If you're only going to be changing it over once or twice per year, I don't see any issue with doing it this way. It may seem "simplest, but would require me to make that square to round conversion and have it strong enough to support a collecton bag. Much easier to install the blast gates. I think I'll just do it that way and see how it works.