Thien Baffle, first attempt failure?

[Holbs]

Thanks to all of those sharing their knowledge about different baffle designs, pro's and con's.  And special thanks to Mr. Thien himself and even Retired2 for which I have learned enough so far to think I can actually fly a little bit.
I started the first true wood working project over the weekend, which was a Thien Baffle attempt.  Here is my story:
1.)  3 HP grizzly dual bag dust collector (will find out if the baffle can handle 3HP or not soon enough).
2.)  baffle chamber will be 16" tall, with 6" circular spiral duct squashed down to 8" x 4.5" inlet, 7" outlet with bellmouth (whenever Penn State gets one in stock)
3.)  1/2" MDF with 1/8" hardboard.  Middle baffle plate will be recessed 1" under the 1/8" hardboard.
4.)  sitting on top of a 55 plastic barrel.

I think because I just registered, I can not post pictures.  I'll do so later.  Basically, I think I failed engineering right off the bat.  My cut out for the baffle, I think, starts TOO early which makes the end of the cut out end TOO early as well.  The end of the arc is not 1" or so from the inlet...but 7" or 8" before the inlet.   Not sure why this did not sink in during the rough draft with pencil layouts.
How critical is the position of the cut out arc, beginning to end?  I did a quick google image search and found other's also have done this and they say everything is AOK.  Would like to know now while I have opportunity to start from scratch.
-eric

[Rkapple]

Hi there  - nobody else with more experience than I seem to be jumping in here so I can give you my limited bit of experience - I am just getting a double high working - my dimensions are 13 1/2" high and 18" in diameter. I am finding the dust is making at least half a revolution to as much as 1 1/2 revolutions before it disappears - so though I am not positive but I am pretty sure it is going to work for you as it is.
Out of curiosity what is your diameter? I only have a 1 horse collector hooked up, with a 3hp collector I would be making the diameter as large as I possibly could. Depending how you are setting it up but you could possibly even go to a 24" diameter and install a tapered section to fit your drum below the baffle. A 55 gal drum is going to be pretty heavy when you get it full. I also found that installing a bell mouth on the outlet intake was a definite improvement. I just made one up from MDF. I played around a bit with height and ended up with the intake for the outlet above 3" above the baffle.

[phil (admin)]

Just cut another one.

What about that bevel I'm seeing on the MDF piece under the baffle?

[Holbs]

Phil...  after seeing alot of videos of the baffle in use, I always noticed stray debris accumulation where bottom lexan met wood with the use of a retaining lip for the lexan.  Figured, a 45 degree bevel from lexan on downward might help with that.  If anything else..  it looks sexy :)
And yes..  I redid the baffle plate as I found out I goofed my circular diameter by 1/2", which would of had the underneath weather stripping inside the arc cut out area.

Apple..  55 gallon plastic drum underneath with a 23" wide top.  I"ll later modify it so that I can somehow line with a 55 gallon trash bag and just wheel it out for trash truck directly.  Should be fun to see how many swirls in a 16" high chamber it takes.  Maybe I should put multicolor disco LED lights in the chamber.  Might be better than watching a fireplace some evening.

[jgt1942]

Might I suggest that a 55 GAL container is too large. When full it might be too heavy especially as you get older. I currently have a 20 GAL Brute and that is TOO small and will be modifying to fit a 32 GAL Brute. Following is my current unit, 3HP Grizzly and I'm using 4" intake so far for my shop this has been great. When I first fired it up I had a HUGE pile of dust under my table saw and it sucked it up with no issues.

[jgt1942]

OK I could not get all three pic in the previous post

[Holbs]

more progress.  I am also running a blog on this project over at LumberJocks so that other new person's getting into wood working can be inspired to do needed projects, especially healthy ones.
Nothing is sealed as I wanted to do a dry run.  Tossed a handful of planer shavings.  And from my eye, it looked like 100% shavings reached the bottom of the barrel.

JGT..  I "thought" my grizzly had a 7" inlet, as that is what I read all over the place (never measured it myself).  But, 6" inlet it is.  And you put your's up top...   I really considered that but concerned about the bearings being unhappy at horizontal instead of vertical, and couldnt figure out how to make my 2 arms out to the bags work without modifying the metal arms themselves.  You have a single bag on a 3HP?  and about using a 55gallon drum.  I am hoping to find a way to line it with a plastic bag so I can just wheel it straight out for the garbage truck.  Or...  lay it on it's side and slide it out.

[jgt1942]

Senior moment on my end - My unit is a 2 HP. I think the bearings are sealed and I don't think it really makes any difference what position they are put in. However I could be wrong.  :-\  If I'm wrong I will have a major modification. I was attempting to avoid as many bends as possible. Currently it is working great.

With the Tophat I'd suggest that you don't need the double set of bags on your output and would block one of the outputs with a board or piece of metal.

Following is the current product of my efforts. I have a few mistakes and will be modifying my unit in the near future. I used the upper/lower bags on the output just because I had them on the original unit. On the right side I have a metal ring on the bottom of the tophat, currently there is not enough room to slide a 32 gal Brute under thus currently I'm limited to a 20 gal Brute (this is MUCH TOO SMALL).  I fear that the 55 gal drums would be a royal pain to empty. I think you will be really surprised how quickly they will be filled. I just completed a 60" x 32" reloading bench top for my neighbor that I made from scrap 2x4 and by the time I completed the joining, planning, and sawing I had about 60 gal of dust. Most of this was done in one day. 

As you can see my unit is on wheels thus allowing me to easily move it in my double-car garage. As I connect to different tools I finding myself not happy with the portable aspects and I'm thinking of rebuilding and making it fixed this of course means I need to install duct pipes (this I was trying to avoid).

When I make the modification for the 32 gal Brute I will install a heavy duty plastic bag (I get them from CostCo) and to keep the bag from sucking up I will get a piece of laminate flooring, cut it so it will be in a circle all the way around the inside of the plastic bag and top-to-bottom of the Brute. When the bag is full I can easily remove the laminate, seal the bag and remove it with no almost dust. Currently when I remove the 20 gal Brute I have to empty it either into the bag I will use for the 32 gal Brute or just dump into the city trash container. Either way with this method I get a lot of dust flying.  :-[

Another mod I want to make is automatic shut-off when the collector can is full. With my first real usage with my current setup I was working with the planner and noticed that the tophat was full which meant the can was stuffed. Gee what a mess this made.

On my Grizzly the output of the impeller is connected to the dust bags via a flex hose. This flex hose was part of the original unit, I just shortened it to make the connection between the two.

[retired2]

With the Tophat I'd suggest that you don't need the double set of bags on your output and would block one of the outputs with a board or piece of metal.

I wouldn't rush to block off the filter bag opening.  It might not be needed for filtration, but it might help with airflow especially once they get a little cake as they surely will in time.  One quick test is watch to see if they are both still inflating with the top hat installed.  If they are, you probably still need them.  If they are hanging limp, then block one and see what happens with just one bag, but if it fully inflates, I'd go back to two.

[Holbs]

98% finished.  sealing all done and tested aok with a handful of planer shavings.  still have to fine tune the outlet height and possibly add a bellmouth.
and yes...both bags inflate so i will not be blocking off one of the arms.

[retired2]

98% finished.  sealing all done and tested aok with a handful of planer shavings.  still have to fine tune the outlet height and possibly add a bellmouth.
and yes...both bags inflate so i will not be blocking off one of the arms.

Looks like you are a little space limited like many of us hobbyist woodworkers, but you could make a big difference in air flow by replacing all those 1D elbows with longer radius bends.  Those short radius bends "eat your lunch".  Also, that tight bend close to the fan inlet is also a performance robber!

[Holbs]

i could easily go back and install 45 adjustable elbow to another 45 adjustable elbow.    hmm.. i do have spare elbows.  i'll give it a shot.  the pieces are just duct taped together til everything is 100%, they i'll apply 'pookie' (as the HVAC call it) which is they grey toothpaste stuff.
i see alot of people use the 10' hose with even more severe bending.

[rickc]

Seems 2D elbows are high priced, so my plan is to use two 1D elbows together.  Did buy twice as many.... one of these days.

[retired2]

i could easily go back and install 45 adjustable elbow to another 45 adjustable elbow.    hmm.. i do have spare elbows.  i'll give it a shot.  the pieces are just duct taped together til everything is 100%, they i'll apply 'pookie' (as the HVAC call it) which is they grey toothpaste stuff.
i see alot of people use the 10' hose with even more severe bending.

There's only one thing worse than 1D bends, and that's tight bends with flex hose.  Flex hose has approximately three times the losses of a comparable smooth pipe! 

[Holbs]

*** months later for an update ***

Wow...  this Thein baffle has done EXACTLY what it was suppose to do.  Have emptied out the blue barrel 6 times after being near 85% or so full.  Just this weekend, I installed 2 Wynn Env 35a filters and 2 clear plastic bags for my dual bag dust collector.  Which gave me a reason to empty my 2 old 30 micron (or maybe 20 micron?) original bags, there was about 6 gallons of brown looking sugar... oh wait... I mean fine dust. 
What a great first wood working project.  Learned alot about do's and dont's here on the forum and abroad.
a short video of baffle in operation:  https://www.youtube.com/watch?v=KmymX5WW88s
My lumberjocks project posting of the baffle: http://lumberjocks.com/projects/98274

Retired2... yes, I eventually put 45-45 elbows at each bend for the feed into the impeller.  Had to move my Grizzly back a little bit more but that's ok.