J. Phil Thien's Projects

https://www.woodworkforums.com/f200/generic-2hp-dc-171247/2#post1659193

Woodworkforums.com>Hand tools & machinery>Dust extraction>The generic 2HP DC>post number 21

See if that works

On the HF dust collector, the outlet of the impeller housing is about 6x4 inches, then gets choked down to a 5 inch round house. Not a huge choke, but a choke none the less. On an Australian woodwork forum I read about someone that replaced the round hose with a rigid adapter that matched the dimensions of the outlet on the impeller housing.

https://www.woodworkforums.com/f200/.../2#post1659193

Has anyone on here tried that, and if so, HOW, and what did you think of the end results?

Can anyone point me to research on the best location for the hose port on a blade guard.? I've seen some placed at the rear of the guard, others focused on the front of the blade. I'm trying to decide which way to go.

I have no idea if this is viable or not.  Would a rectangular duct with a cross section area equal to that of and 8 or 10 inch round duct be usable in a dust collector system?

What kind of flex hose are you using to connect to the 6" ductwork, and where did you source it?

Like R2 said, put the inlet as high as possible. 

I have a theory regarding how high above the baffle the outlet should be.  I haven't been able to try it out yet, and others on this board have voiced skepticism about it.  They may be right, it might not work.  But here is my idea.  Divide the area of the outlet (for a 5 inch duct, that would be 19.635 square inches) by the circumference of the duct (again, for a 5 inch duct, this would be 15.708 inches).  For 5 inch duct, this would give a result of 1.25 inches.  My theory is that this would be the minimum clearance between the baffle and the outlet.  More than this would be okay, but less than this make the outlet "starve for air".  However, I don't know yet how much a low clearance like this would contribute to bypass. Bypass in a separator is a bad thing...

Let us know what you go with and how it turns out!  Good luck!

pics of jtull01's setup...
Any thoughts on what may be causing his problems?

http://i268.photobucket.com/albums/jj8/jtull01/IMG_3507_zps0zedjsjt.jpg
http://i268.photobucket.com/albums/jj8/jtull01/IMG_3508_zpsednokv9r.jpg
http://i268.photobucket.com/albums/jj8/jtull01/IMG_3512_zpsn0ytfvyp.jpg
http://i268.photobucket.com/albums/jj8/jtull01/IMG_3511_zpseln2pg2m.jpg
http://i268.photobucket.com/albums/jj8/jtull01/IMG_3509_zpsdnvtc7jn.jpg

Jeff,  could you post some pics of your build?  That might help us sort it out.
Zane

Quote from: Jtull01 on April 01, 2016, 04:07:25 PM
Hi
So I built the HF mod. 20 gal trash can, Wynn filter, etc.
My problem is I get a vortex in my bag and barely any collection in the can! I used 5" metal duct into the Thien baffel and have a 6" drop from the lid. I have a 2.5" drop on the turbine tube into the lid, also 5".
Help what did I do wrong?
Thanks Forum
Jeff

Bought the HF unit in January, still haven't put it together, but have already made changes to it while in the process of building the tophat.  I've replaced the impeller with the Rikon, purchased a Wynn cartridge, and have replaced the impeller inlet plate with a plywood plate and opened it up to six inches.
Testing just the motor/impeller assembly on the bench without any filters on the outlet, or any ducting on the inlet, and using a clamp on meter to test the current draw, I am showing 80 amps startup current and 20 amps running current.  I have this on a dedicated 20 amp circuit.  I hope that once I get the system all put together, the current draw comes down some.  Otherwise I may have to put in new wire, breaker, and outlet...

Clark, I like that third option.  Reminds me of a setup I've seen to simulate different amounts of drag on the intakes of a DC system. 

I like the looks of it!

Of course, I like the looks of Ferrari's too...

Below is a snip of advice I received on top hat design:
<snip> the key is to keep the outlet below the inlet but high enough from the baffle so as not to restrict flow <end snip>
I am not divulging the source of this advice as it was a private communication.

This, I believe, kind of leads us toward having the double height chamber.

The OCD part of me wants to design a variable chamber height/variable outlet height top hat to experiment with different configurations.  But life happens while you're busy making other plans.   :)

Actually, I am planning to use an approximate 3x9 inlet.  However, as pointed out, continually increasing the height of the top hat can become a problem in a home workshop.  My shop is in a basement with a 7 foot 4 inch ceiling.  My situation requires some compromises; rectangle dimension and chamber height is one of them, straight shot distance on the inlet is another.  However, I am trying to maximize the best choices I can in as many places as I can.  Hopefully, this will optimize the system enough to overcome the places where I have to make compromises

In a perfect world, my inlet rectangle would be 25-1/8 high by 1-1/8 wide (the same width as the drop slot).  But in my shop, that just ain't happenin'.  That said, I would really like to hear of someone who does have the luxury of headroom and a system powerful enough to try it! 

The quest for the perfect Thien, so much dust, so little time...

Resurrecting an older post.  I am still in the drawing stages of my build.  Drawing, erasing, drawing again, etc.  I have a theory about the outlet height.  The numbers used in my theory are based on 6 inch diameter duct work, and on a baffle to top height twice the diameter of the duct, which in my case would make a 12 inch chamber height. 

First, imagine that you have your outlet pipe all the way down against the baffle so that no air flow could occur.  Now, imagine that you want to cut a rectangular window in the side of the bottom of the pipe to allow air flow.  My theory is that the area of this window needs to be at least the same, or larger, than the cross-sectional area of the duct.  With 6 inch duct, the cross-sectional area is 28.27 inches.  If, for example you cut a window 1.5 inches high and 9 inches long, the area of the window would be 13.5 square inches, which is less than the cross-sectional area of the duct, and would be choking the air flow.  Keeping the window at 1.5 inches high, but continuing to cut the window longer and longer, until you have completely cut the circumference of the duct, you will have effectively made a window 18.85 inches long (the circumference of the duct) by 1.5 inches high.  The area of this window, 18.85x1.5=28.275, is very close to the cross sectional area of the duct. 

So, my theory is that if you take the cross-sectional area of the duct (radius squared x pi), and divide it by the circumference of the duct (2 x pi x radius), that will give you the minimum dimension that you can put the duct to the baffle without choking the airflow.  That close to the baffle, I am pretty sure that you will need to be using a bellmouth outlet to minimize turbulence.  As far as airflow goes, I would think that you might see an improvement if you increase the height up to 10 percent, which in this case would be 1.65 inches high.  After a 10 percent increase, I don't know if you would see any more improvement in airflow.  All of this speaks to airflow only, not to turbulence, by-pass, or scrubbing.  But this is going to be my starting point.

Along these lines, does anyone have a suggestion as to how to make the outlet duct height adjustable, yet air tight, for testing purposes?

And, R2, as so many others have said, thank you for sharing what you have done on your build.  Of course, Phil is the beginning of this whole concept.  Everyone that has tried something new, and shared it, whether it worked or not, has been of great help.  Let me say that again in a different way.  Anyone who tries something new, EVEN IF IT DOESN'T WORK, please share it!  BOTH the successes AND the failures are a big help!

I'm interested in the current sensing part of the system.  Could you draw up a quick and dirty schematic of it?

TIA

Phil, PM sent.