# Making an Internal Thien Baffle for a HF Dust Collector



## rexb (Mar 28, 2012)

*Making an Internal Thien Baffle for a HF Dust Collector*

I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.

I used 1/4" MDF for the baffle. Many people use hardboard, but I have a really hard time finding stuff that is smooth on both sides. First I laid out the dimensions: 19" outer diameter with a 1.25" wide annular segment removed for 120 degrees of the circle.










I used my jigsaw to rough cut it out, making sure to cut outside the line.










Next I rigged up a simple circle-cutting jig for my router table. I put my shop-vac hose close by to catch some of the MDF dust, but it still made a nasty mess.










After cutting the drop slot with the jigsaw and router table (same way as before) and drilling 3 mounting holes, the baffle was complete.










To mount the baffle, I used 1" dowels and put hanger bolts in both ends. This way I could secure it with nuts and the baffle would be removable. The dowels need an angle on one end to mate with the dust collector ring, so I predrilled for the hanger bolt before cutting the angle.










This allowed me to use the offcuts as angled washers.



















Finally, I filled the center pivot hole in the baffle with epoxy and gave it a few coats of polyurethane. I did this so that hopefully the dust will stick to it a little less.



















In all, this baffle probably cost me about $15 for materials. In use, it definitely looks to be doing its job. Anyone who has this dust collector knows that the dust likes to swirl like a tornado in the bottom bag when it is turned on. This baffle has just about eliminated that swirling, so it should be keeping the filter bag cleaner. After using it for a few weeks, I noticed a few small leaks at the seam in the blower housing, so I sealed those with some caulk.










I also put some weather stripping around the bottom of the collector ring where the lower bag seats. Those efforts seem to have sealed things up nicely.

Right now I just use this dust collector for my tablesaw, and it works very well. It definitely cuts down on the mess I make quite a bit. Eventually I will have a jointer and planer as well, and will hook it up to those. I'm sure it isn't the best dust collector out there by a long shot, but fits my needs nicely and cost about $170 including the baffle. When I get the money I do plan to add a Wynn cartridge filter, but for now I'm pleased with what I have. Thanks for reading!


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## Kentuk55 (Sep 21, 2010)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Looks like it will work like a charm. Nice job, and nice "how-to" as well.


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## NormG (Mar 5, 2010)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Thanks for the pics


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## dwwright (Jan 12, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


I was wondering if this could be done, didn't want to mess with extra can and hoses for the Thien baffle. So how is it working out? Have you noticed a difference?


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## rexb (Mar 28, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


It does what it's supposed to. When I first bought this dust collector, the dust would swirl in the bottom bag like a tornado. The Thien baffle has stopped that swirling, and therefore the upper bag should be staying much cleaner. I'm definitely glad I did this. I'm not the first to put my Thien baffle in that location.

The advantages of an internal Thien baffle are:

Simple construction
Space and material savings
No pressure drop

The advantages of an external Thien separator are:

Keeps filter even cleaner if working correctly
Separates large chips and debris before they hit the impeller
Easier to empty when full


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## JoeinGa (Nov 26, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Nice. Thanks for the pictoral


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## dwwright (Jan 12, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Cool. Thanks Rex! I ordered the Wynn filter yesterday. So will get both installed this next week. Another member over on Family Woodworking had used a wok pan mounted in his upside down, which does about the same, but I've got the MDF and dowels for doing the Thien method.


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## DW833 (Mar 31, 2013)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Can the internal baffle be used with an canister filter, like a Wynn 35Axxx?


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## DIYaholic (Jan 28, 2011)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


DW833,
YES!


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## rexb (Mar 28, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


*DW833* - as DIYaholic said, YES! The main purpose of the baffle is to keep the filter clean, which is mostly a concern when using a canister filter. I just haven't upgraded my filter yet, but I will as my budget allows.


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## dorald (Jun 29, 2013)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Dear Rex B
I just finished talking with Dick Wynn, and he said your method is definitely the right way to go. It wasn't an endorsement just that it was definitely the correct way to go.

I made the mistake of letting my Wynn air filter get too congested. It took a long time to clean it out. Dick mentioned that never let the debris bag get more than a quarter full although with the installation of this baffle you can get it let it get fuller, maybe half.

Dick also mentioned never wash the filter. Use compressed air not above 80 psi. and the combination of dropping it against the ground from a height of 2 to 3 inches so's not to damage the filter or the housing.

Just thought I'd pass what I just learned along . . .

Dick Wynn sounded very approachable and eager to help in anyway you could. He invited my call again should I have more questions. Great customer service!


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## dorald (Jun 29, 2013)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Dear Rex B
I just finished talking with Dick Wynn, and he said your method is definitely the right way to go. It wasn't an endorsement just that it was definitely the correct way to go.

I made the mistake of letting my Wynn air filter get too congested. It took a long time to clean it out. Dick mentioned that never let the debris bag get more than a quarter full although with the installation of this baffle you can get it let it get fuller, maybe half.

Dick also mentioned never wash the filter. Use compressed air not above 80 psi. and the combination of dropping it against the ground from a height of 2 to 3 inches so's not to damage the filter or the housing.

Just thought I'd pass what I just learned along . . .

Dick Wynn sounded very approachable and eager to help in anyway you could. He invited my call again should I have more questions. Great customer service!


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## dorald (Jun 29, 2013)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


REX - What is the length of the 1" dowels you used and how far does this put the baffle from the cove surface?


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## rexb (Mar 28, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Dorald, I don't know what length the dowels are exactly, but they put the baffle right above the bent lip at the bottom of the DC ring, as you can kind of see in one of the pictures above.


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## splinter1000 (May 4, 2014)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Hi Rex,

I was wondering if you could tell me how well the internal baffle is working , especially in terms of keeping dust out of the upper filter bag?

Kindest regards


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## rexb (Mar 28, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


It's hard to say exactly how well it's working, because I still haven't upgraded to a canister filter. The big difference I do notice between my dust collector now and when I first got it is that there was a whirlwind of chips always swirling in the lower bag, and the baffle has stopped that. So I think the filter must be staying cleaner than it would have otherwise.


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## Sigung (Nov 20, 2013)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Thank you so much for posting this. I've been looking at Thien baffle plans all morning after buying the same HF DC that you have. After looking at the $175.00 filters from Wynn Environmental I have decided it makes more sense for me to vent it to the outside than it does to spend more for a filter than I did for the DC.


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## ArlinEastman (May 22, 2011)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Rex

I seen what you done but it is not clicking for me on how it is working. Is the baffle higher than the inlet or lower? How is it keeping the dust from going into the bag?

Thanks


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## rexb (Mar 28, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Arlin - The baffle is lower than the inlet. The basic idea is that the baffle prevents dust and chips in the bottom bag from being scrubbed back up into the filter. With the baffle, what goes to the bottom stays at the bottom, which wouldn't always happen otherwise.


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## 1Woody (Mar 20, 2013)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Rex do you know if there is a difference in drop of pressure if I were to use the internal versus the external baffle?
I have an external barrel with the baffle already set up and now after reading yours here am wondering if I would be better with just the internal baffle. I have a Powermatic 3HP with double bags, 2 on each side of the impeller?


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## rexb (Mar 28, 2012)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Al - Sorry, I just saw your comment. I think an external separator is definitely superior to the internal baffle. The main reason to go with the internal baffle is for space savings. I do think that an internal baffle would give less pressure drop, but with your 3HP setup I bet it's not an issue.

The big advantages of the external separator are ease of emptying and the fact that it separates out large chips before they hit the impeller.


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## DDWW (Sep 7, 2016)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Thanks this helped me to just see it. I was thinking about a trashcan separator but I may try this first.

I may put one in my jet this weekend. I have some threaded rod so I may use that instead of dowels. It was nice to see it rather then just read about it.


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## Acts65Woodworks (Nov 30, 2016)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Thanks for sharing your work. Do you see any point in having both and internal and external baffle? Or is that just overkill?


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## Acts65Woodworks (Nov 30, 2016)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


I picked up a HF dust collector on Craigslist the other day. I am planning on making an external Thien baffle, but am not sure when I will get around to it. I saw this post on the internal baffle and put one together pretty quick. Tt seems like a great modification until I get around to making the external one. This is the first time I've seen this modification posted. Thank you for taking the time to explain!


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## costalot (Jan 18, 2021)

rexb said:


> *Making an Internal Thien Baffle for a HF Dust Collector*
> 
> I was lucky enough to get the popular Harbor Freight 2 HP dust collector for Christmas. People have modified that thing in every way imaginable, so I found plenty of inspiration out there when planning what to do with mine. I decided to keep it fairly simple: a Thien baffle inside the dust collector's separator ring, to hopefully keep the dust in the bag and not in the filter. A lot of people have done this mod, but most of them don't post pictures because it is so simple. So I figured a quick pictorial of how I made mine might help someone in the future.
> 
> ...


Nice Idea!


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