Internal Thien Baffle for HF DC

Darren, I went through your tutorial. Great job and thanks for the tutorial. I have it bookmarked for my build.

Good deal Paul. Let me know if you have any questions.

FYI the efficiency of the separation is generally considered to be inversely proportional to the thickness of the baffle (up to where the baffle starts to flex and then not so happy). The 1/2" seems moderately thick for a baffle from what I've seen (there are a ton of variables though so I can't say how well it will or won't work..). If you find a lot of fine dust is still getting up into the filter, try a thinner baffle, like 1/8" or 1/4" hardboard, masonite, ??new wonder material??.

I used a 3/4" piece of plywood for the baffle part of my top hat. I originally just beveled the edges back a bit (actually its more complicated than that, I had a piece of sheet metal on top with a ~1/4" lip on it then the bevel on the plywood; I eventually had to remove the lip in order to widen the slot so it didn't clog with shavings.. and yeah so anyway..) but that didn't quite cut the mustard for finer dust. Eventually I ended up routing the bottom of the baffle down so it is ~1/4" thick and then hand beveling the edges back from that which worked pretty well (because of how the top-hat was made I'd have had to re-build the whole thing in order to replace the baffle - since then I've seen a design for a "sandwich" where the baffle itself is replaceable which looks a whole lot smarter of an idea). What I learned from that was

• Make the parts replaceable if you can
• thinner baffle is better baffle, and thinning the edge helps but not as much as having the whole baffle thin. I sort of vaguely grok what the airflow is probably mostly doing and it does travel across the bottom of the baffle and return so having that be a smooth flow seems to help as does having both the top and bottom be smooth (the bottom on mine isn't perfectly smooth and it does accumulate some dust in some dips, you can even see the flow direction from that, kinda interesting).

Ryan Mooney said:

What I learned from that was

• Make the parts replaceable if you can
• thinner baffle is better baffle, and thinning the edge helps but not as much as having the whole baffle thin. I sort of vaguely grok what the airflow is probably mostly doing and it does travel across the bottom of the baffle and return so having that be a smooth flow seems to help as does having both the top and bottom be smooth (the bottom on mine isn't perfectly smooth and it does accumulate some dust in some dips, you can even see the flow direction from that, kinda interesting).

Click to expand...

Ah, I may have to make a thinner one then. Luckily the current one will make a great template.

I actually had considered using a piece of 1/8" masonite, but didn't have a piece wide enough. Thanks!

I was thinking 1/4 in. hard board. I wonder if it helps to varnish/paint it or anything?

Darren,
I wouldn't get to stressed if its working well, but figured if it wasn't that would be a nice FYI

Paul Douglass said:

I was thinking 1/4 in. hard board. I wonder if it helps to varnish/paint it or anything?

Click to expand...

A coat of something smooth like shellac wouldn't hurt anything if only to reduce the wear on it. I didn't coat the bottom of mine, but the top is sheet metal. I can see the bottom collects some dust on it, but not enough to stress about.

I'm finally ready to start my mod on my DC. I went to the store today to buy a piece or temper board to make the baffle and I don't know why but I came home with 1/4" instead of the 1/2". Any reason 1/4" wouldn't be usable?

1/4" should be fine - i'm using 24ga sheet metal and it's holding fine

Thanks, Jason. I'm all over this little project, starting tomorrow!

Paul, I'm pretty sure I used 1/4" for mine. You should be fine with what you have.


Sent from my iPhone using Tapatalk

Will I got the baffle installed today. If I did it correctly, it was a pretty easy mod. I spent about 2 hours cleaning my filter, beating, blowing and vacuuming. Almost as clean as it was when I got it. Tomorrow I am going to come up with a way to attach the filter so I can get at it from the outside. I don't have any of the right sized rubber tie-downs so I think I will use some cable I have, go over the top in three places and tighten it down with the turnbuckles on the outside. If anyone see a problem with my setup, please speak up!

Looks good, Paul!

I had a little trouble with round bungee cords staying put - s'why i went with the rubber ones. Cable makes me think round, too - might be finicky to get on and stable. Does your filter have a good thick foam ring on the bottom? If so, just a little weight setting on top would keep it on until you got a better solution in

You are right, I had already decided against the cable. Have to deal with cable clamps and all. I'm going to make a run to the store and pick up the rubber tie-downs.


Okay, I had two tiedowns that were short enough so this is what I ended up with. Seems to hold it fine.

Two things I noticed when I turned it on. It is quieter than before. I don't know it that is because of the baffle or because I spent so much time cleaning the filter. Maybe a little of both.

I have a slight whirl of sawdust in the bottom bag when I first start it up but it seems to go away. There is not much in there right now so I will see what happens when I use it more. Time will tell, but I think I am happy with it!

A little late to the party, but I had two of the round bungees the right length. I used a couple of wire ties to connect them where they crossed one another to keep them from slipping off.

All looks real good Paul, nice work!

I took my filter off today to see what was happening in my new setup. Appears to be working exactly as described. I'm very happy with it.

Quick Harbor Freight Thien Baffle Modification

For those of you who have not decided which separator modification to do to your HF Central Machinery 2 hp Dust Collector, let me share what I decided to do with mine.
I won’t try to convince you either way about the Thien baffle because there is plenty of info already out there.

I started with a new Harbor Freight Central Machinery 2 hp Dust Collector.
($182.68 delivered - Jan 2014)

After much research, I decided that the lowest level of separator modification would be to add a Thien baffle to the filter housing between the bag and the filter. I looked at several innovative and well-crafted renditions before deciding on ¼” plywood and ‘L’ brackets.

Materials
1 - 19” diameter ¼” plywood disc
3 - ‘L’ brackets (¾” x 3”)
6 - 8m-1.25 nuts
4 - #10 x ¾” flathead machine screws w/nuts
Optional - plywood finish

Pros
*Uses existing airflow spin in housing to diminish separator losses
*No changes/drilling/cutting to unit
*Assemble as intended with some additional pieces.
*Revert to stock condition if you don’t like your results.
*Low cost
*Fast and easy

Cons
Pressure feed places the impeller in the debris flow.
At this time I am not concerned with this mainly because my unit came with a metal impeller. Also, I think pressure feed is more efficient.

Note:
This is a rehash of various ways I have found, on this and other forums, to install a Thien Baffle. There is very little original thought in this project.

The Modification

To make the baffle I simply:
traced the inside housing diameter onto the ¼” plywood,
marked the 120 degree pie slice,
marked the 1 ½” wide 270 degree slot diameter line, and…
cut it on the bandsaw.


The original bolts are long enough to add nuts to hold the brackets.
The ‘L’ brackets need two holes large enough to fit over the stamped threads that hold the legs to the housing.


The brackets perfectly positioned the plywood at the bottom of the housing.

I test ran the unit by collecting some planer shavings which ended up neatly in the poly bag. While running with the filter bag off, I had difficulty seeing anything in the exhaust. The initial trial with no filter showed that the baffle works very well, but since it’s 2 degrees F now, I think I’ll wait till next week to run a formal test.

In any case, I am convinced that the reduction of debris migration into the filter housing is sufficient to allow the use of a 1/2 micron filter.

Welcome aboard, Mike. As someone who's done essentially the same modification to my Harbor Freight DC (and who also has the 0.5 micron Wynn filter), I'm certain you're going to be very pleased with the separator. It won't keep everything out of the filter, but it's MUCH better than without.

Thanks for the feedback, Vaughn. It’s an easier trip for me down the path you and others have blazed.

Which Wynn filter do you have? I am leaning toward the #35A274BLOL 80/20 blend:

Our 80/20 Blend filters have a MERV 10… they last for many years and they are the least expensive filter in our line-up. A good choice for non-commercial woodworking.

Click to expand...

I could vent outside, but that requires a fixed installation and I need flexibility at this time. An added advantage of installing a Wynn filter would be the ability to use the setup inside the house remodel/expansion next year.

Mike Morris said:

Thanks for the feedback, Vaughn. It’s an easier trip for me down the path you and others have blazed.

Which Wynn filter do you have? I am leaning toward the #35A274BLOL 80/20 blend:


I could vent outside, but that requires a fixed installation and I need flexibility at this time. An added advantage of installing a Wynn filter would be the ability to use the setup inside the house remodel/expansion next year.

Click to expand...

I have the 35A100SBOL, but not sure why I decided on that one over the one you're looking at. The baffle has made a huge difference in the amount of dust getting into the filter though.