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Dust collector separator -where do I place the outgoing hose: center or side? Above/below intake?

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Forum topic by MiniMe posted 01-18-2020 08:08 PM 855 views 0 times favorited 10 replies Add to Favorites Watch
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MiniMe

384 posts in 682 days


01-18-2020 08:08 PM

The logic tells me that the outgoing hose should suck air from the middle of the vortex AND it should do it as high as possible since the dust and chips in the vortex have a descending trajectory These systems seem to contradict my theory. Why?

Th Lee Valley system sucks from the central point of the lid (vertical axis of the barrel)

Then there is the side option:

and then there is the very engineered Thien baffle thart also takes the air from the middle


10 replies so far

View Andre's profile

Andre

3061 posts in 2437 days


#1 posted 01-18-2020 08:24 PM

On my Veritas the inlet is the centre, works fine, I do have a partial baffle below the outlet.

-- Lifting one end of the plank.

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Sark

244 posts in 991 days


#2 posted 01-18-2020 09:59 PM

The dust goes in the side, and starts spinning. Centrifugal force causes the dust to be pushed to the side where it falls to the bottom. The air continues its trip (without dust) out the middle.

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MiniMe

384 posts in 682 days


#3 posted 01-18-2020 10:35 PM

Already drilled my holes in the lid
Now the question is how low do I need/want to go with each (intake / outake)
I am seeing some videos showing the Thiem baffle where the air enters the baffle from the side at the same level with the intake which means it does not matter. If I want to install a baffle later then have to be approximately at the same level ..

View Walker's profile

Walker

222 posts in 1103 days


#4 posted 01-18-2020 11:09 PM

http://www.jpthien.com/cy.htm

FORUMS:
http://www.jpthien.com/smf/index.php?PHPSESSID=6ea17c095b79d1a3e3916f754da9d7bc&board=1.0

From the legend’s very own website. You’ve got several days worth of reading ahead of you.

-- ~Walker

View MiniMe's profile

MiniMe

384 posts in 682 days


#5 posted 01-19-2020 12:20 AM



http://www.jpthien.com/cy.htm

FORUMS:
http://www.jpthien.com/smf/index.php?PHPSESSID=6ea17c095b79d1a3e3916f754da9d7bc&board=1.0

From the legend s very own website. You ve got several days worth of reading ahead of you.

- Walker


I said PASS to that…I can live with some dust in the dust bag of my DC
I did find the website a while ago

View HuckleberryWoodWrks's profile

HuckleberryWoodWrks

45 posts in 33 days


#6 posted 01-19-2020 12:39 AM


http://www.jpthien.com/cy.htm

FORUMS:
http://www.jpthien.com/smf/index.php?PHPSESSID=6ea17c095b79d1a3e3916f754da9d7bc&board=1.0

From the legend s very own website. You ve got several days worth of reading ahead of you.

- Walker

I said PASS to that…I can live with some dust in the dust bag of my DC
I did find the website a while ago

- MiniMe

I only said pass because I got a super deputy. I did have a Thien before I got a DC. A separator makes life so much better. Less dumping and at least seems like less dust in the air. I also added a can filter off the outlet.

From what I’ve read, those lid separators are only ok. A Thien or cyclone drops more dust and chips before your outlet. I’ve used both, but not the lid, so only speaking from what I’ve read.

View Walker's profile

Walker

222 posts in 1103 days


#7 posted 01-19-2020 01:42 AM

The Thien baffle really isn’t that expensive, difficult, or time consuming to build.

Regardless, you asked about the science involved. The folks on the Thien forum have broken down every aspect of the build including placement/size of the intake and outtake ports, thickness of the baffle, width of the drop slot, depth of the chamber, you name it. They’ve tested, analyzed, posted results, adjusted and re-tested. If it’s a science question you have, the answer is there.

I know it’s a lot to look through over there, here is one thread that has a lot of good data:
http://www.jpthien.com/smf/index.php?PHPSESSID=ae51e4d1270f9fe74fc368c01e77ce6e&topic=563.0

-- ~Walker

View MiniMe's profile

MiniMe

384 posts in 682 days


#8 posted 01-19-2020 04:28 AM

View Mike_D_S's profile

Mike_D_S

603 posts in 2845 days


#9 posted 01-19-2020 03:09 PM

Ok, some simple rules of thumb here.

1. You want the airflow to induce a cyclone in the container. The spinning airflow carries the particulates (chips, dust, etc) to the wall of the container where they start to drop out due to friction with the wall (on both the particulates and the airflow).
2. The slower the airflow, the smaller the particles that fall out of the airflow. So to get maximum separation you want the outlet to pull from from where the air is slowest, which in a spinning flow is going to be the center.

Most of the separators above are some version of the cyclone which use elbows, air ramps, etc to get the incoming airflow moving toward the wall of the container to help induce the cyclonic motion.

Best exhaust point is from the center as that is naturally the slowest (less particulate laden) air to pull from.

Everything else (and I mean that pretty literally) is a design choice impacting how efficient the separation. Round cyclones, conical, exhaust above or below the intake, etc all just contribute to exactly how much of the smaller particles get recirculated.

-- No honey, that's not new, I've had that forever......

View MiniMe's profile

MiniMe

384 posts in 682 days


#10 posted 01-19-2020 04:47 PM


Ok, some simple rules of thumb here.

1. You want the airflow to induce a cyclone in the container. The spinning airflow carries the particulates (chips, dust, etc) to the wall of the container where they start to drop out due to friction with the wall (on both the particulates and the airflow).
2. The slower the airflow, the smaller the particles that fall out of the airflow. So to get maximum separation you want the outlet to pull from from where the air is slowest, which in a spinning flow is going to be the center.

Most of the separators above are some version of the cyclone which use elbows, air ramps, etc to get the incoming airflow moving toward the wall of the container to help induce the cyclonic motion.

Best exhaust point is from the center as that is naturally the slowest (less particulate laden) air to pull from.

Everything else (and I mean that pretty literally) is a design choice impacting how efficient the separation. Round cyclones, conical, exhaust above or below the intake, etc all just contribute to exactly how much of the smaller particles get recirculated.

- MikeDS


If I use an 90D elbow, can I count on the fact that after one complete rotation the particles will be on a lower spiral already and they won’t hit the back of the elbow creating disturbances in the air flow and reaching the exhaust instead of heading down toward the bottom of the barrel?
If I use a 45D elbow I am afraid that the air could be directed toward the bottom of the barrel and stir up the alrea

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