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Hobbyist wood-butcher
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My dust collector has been a workhorse in my shop, but I feel it really isn’t using its footprint as efficiently as possible. It works but has some serious flaws.

1) Right away, I bump down to 4” from the 5” inlet, so that cuts down on air flow.

2) I only have one elbow after my Thein topper and that is facing down, so when I hook up to any overhead runs, there is a 180 degree turn that cuts airflow drastically.

3) I am using more hose than I really want, which also cuts down airflow.

4) I currently only have 2 blast gates, but am currently moving hoses constantly to hook up to everything.

5) There is a lot of potential wasted storage space under the DC bag, (that I never empty)

This thread will document my effort to make this more efficient and user friendly. Here are 2 pics of my DC as it currently sits.



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The first thing I wanted to do was remake my thein topper. Here are some pics of that process.

This was the first route I made for the recess in the bottom, with my circle cutting jig on my Router table/TS.


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I guess I got so caught up in the rest of the progress (and was having fun with my circle cutting fixture), that I forgot to take pics of the rest of the cuts, but these pics are of the topper before I put in the sheet metal to run along the inside.

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The above picture is of the top upside down, to show the cleat that the metal will be adhered to.
 

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Hobbyist wood-butcher
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Discussion Starter #2
I then cut and formed the sheet metal, and then stapled and caulked it in place. Here are a few pics of it finished.

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That is 5” pvc that I used for the inlet and outlet. I work construction, so when I saw a plumber was running some 5” storm drain, I snagged all the scrap he had, and I think I have enough to do what I intend on doing. It sure was a pain locating fittings for it, but I have and am now waiting for them to arrive. I will then start to work on my manifold, and drawers for under the DC bag, as well as a new “stand” for the DC itself.
 

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Discussion Starter #4
I think that is where I got my inspiration from... I remember seeing a bunch of different scenarios, and I really like the idea of making the curved part with something other than wood. I did my first one totally out of wood, and while it was fun, it took alot longer to build. I am really needing more storage space, especially for DC accessories, and for them to be more accessible. I am planning on making some drawers underneath the bag area. I NEVER have a need to empty my bag, unless I blast the wynn filter with air from the outside. I think my thein separator does one heck of a job, and I just have to clean the wood flour out of my wynn filter once a year or so.
 

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I'm loving this. Exactly what I want to do to get the most out of my DC. Where did you get the sheet metal? Is that something HD carries?

Will you be able to install ducting or are you sticking g with flex?
 

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Discussion Starter #7
I'm loving this. Exactly what I want to do to get the most out of my DC. Where did you get the sheet metal? Is that something HD carries?

Will you be able to install ducting or are you sticking g with flex?
Actually, the sheet metal is something that I work with in my trade. It is 26 gauge aluminum. I have access to 150' rolls of it that are 3' wide. Sorry I couldn't help with that, but I do know HD and Menards do carry some sheet metal. This piece had to be around 42" long though. Not sure if they carry any with that width. If you really need some, PM me. I could probably drop some in the mail to you.

As far as the ducting.... I am going to try to hardpipe as much as possible, but there will be some used. My intention is to cut down the amount of flex by at least half. That might be harder than it looks, since everything is basically mobile. We will see. My main concern is having everything hooked up, so all I have to do is flip some blast gates, and that is it. I spend more time moving hoses around than I want.
 

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What exactly is an air straightener? Is this just straight baffles within the air tube from the separator to the DC impeller? Pictures?
An air "straightener" is another name for a method to convert turbulent flow to laminar flow, which is more efficient.

Normally referred to as straightening vanes.

For a better idea, you need to click on a link within the link in the post.

http://www.banksengineering.com/Fan Troubleshooting ED100.pdf
 

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Discussion Starter #12
This is some good stuff here. I remember seeing that, Bob, but just browsed the pictures. Didn't really read up on it. I still haven't read that much, but I saw the test data, and it seems that air straightener really makes a difference in CFM. I will definitely have to look into that when the time comes along.

Thanks for the great info guys!
 

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Funny, I haven't heard much about air straighteners. Considering the data it's surprising we don't see them more often.
 

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Funny, I haven't heard much about air straighteners. Considering the data it's surprising we don't see them more often.
The centrifugal fan industry has known for a long time that air entering a centrifugal fan with a pre-rotation in either direction will adversely effect the performance of the fan. An air straightener eliminates the problem and improves the air flow.

The pre-rotation of air is much more of a problem when the separator is close-coupled to the fan inlet. The Delta 50-760 dust collecter design encourages many people who have built Thien separators to close couple them. Most people are not aware of the performance hit this creates. I stumbled on it by accident, and after I purchased an anemometer, I was able to confirm and quantify the cfm losses this pre-rotation causes.
 

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Thanks for the response. I'm planning to build a tophat style separater like Fabien's and I think this is very good and timely information. We saw the tube example. Would just putting some flashing across do the job as well (maybe as an X shape)? Are there pictures of others or just the one example so far?

Sorry, one more question: Can you recommend an inexpensive anemometer for this application?

Thanks!
Doug
 

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Thanks for the response. I'm planning to build a tophat style separater like Fabien's and I think this is very good and timely information. We saw the tube example. Would just putting some flashing across do the job as well (maybe as an X shape)? Are there pictures of others or just the one example so far?

Sorry, one more question: Can you recommend an inexpensive anemometer for this application?

Thanks!
Doug
Based on some info from a friend that specializes in air handling systems I made mine in an X shape from thin sheet metal. He wasn't sure about the length needed for my specific application so I am going to experiment with that aspect.
 

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The centrifugal fan industry has known for a long time that air entering a centrifugal fan with a pre-rotation in either direction will adversely effect the performance of the fan. An air straightener eliminates the problem and improves the air flow.

The pre-rotation of air is much more of a problem when the separator is close-coupled to the fan inlet. The Delta 50-760 dust collecter design encourages many people who have built Thien separators to close couple them. Most people are not aware of the performance hit this creates. I stumbled on it by accident, and after I purchased an anemometer, I was able to confirm and quantify the cfm losses this pre-rotation causes.
I forgot to ask how wide is your slot that allows to chips to go into the trash can. Did you make the slot 240 degrees? I have been refering to your info and providing links on this forum based on your info on the Thien forum.

I watched these videos on youtube and it appears he has the slot location wrong based on your design and others.
 

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Thanks for the response. I'm planning to build a tophat style separater like Fabien's and I think this is very good and timely information. We saw the tube example. Would just putting some flashing across do the job as well (maybe as an X shape)? Are there pictures of others or just the one example so far?

Sorry, one more question: Can you recommend an inexpensive anemometer for this application?

Thanks!
Doug
Inexpensive? No. I purchased a Kestrel 1000 new on ebay, about $75. The problem with cheap ones is their working range is too low for dust collection air speeds. Even the Kestrel 1000 is marginal. It could not be used for measuring speeds generated by shop vacs and small bore plumbing.

The way to solve the air speed problem is increase the diameter of the pipe where you plan to take your measurments, then convert the readings to the size pipe you are using throughout your system.

In my case, I was measuring air speeds some distance from the DC and with 5" pipe, but I was still at the upper end of the Kestrel's operating range. If it had been a problem I would have increased the pipe size to either 6" or 8" and then converted the readings to 5" pipe which is what is used throughout my system.

The bearings in most anemometers are pretty fragile and that is why you don't want to run them at speeds outside their stated safe range.
 

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I forgot to ask how wide is your slot that allows to chips to go into the trash can. Did you make the slot 240 degrees? I have been refering to your info and providing links on this forum based on your info on the Thien forum.

I watched these videos on youtube and it appears he has the slot location wrong based on your design and others.
Part 1-5 Thien Top Hat Dust Separator Build - YouTube
My top hat design, other than the rectangular inlet, bellmouth outlet, and air straightener, follow Phil Thien's standard recommendations. I think my drop slot is 1-1/8". The video you linked is definitely showing the slot in the wrong location.
 
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