J. Phil Thien's Projects

Here is an option that can be purchased at common retailers in the ductwork section.  Airflow increased by 10% when I added an un-modified 5" to 6" reducer fitting to the end of a 5" duct recently.  You could cut along the orange line and this would likely increase airflow further.  Measurements were made with a pitot tube and digital meter.  I will post details in a separate thread very soon.  Cheap and readily available, many sizes available, what's not to like?

This is an excerpt from a dust collector review that is no longer available on the Porter Cable website.

If the distance between the baffle and the top = the diameter of the outlet pipe, then it doesn't matter - 1/2 pipe diameter from top or baffle is the same level.

If your top hat is taller then the outlet pipe diameter, then I believe most designs end the outlet 1/2 pipe diam. above the baffle.  Scan the site for other builds to confirm this.

Sorry for the slow response - busy time of year.

Sketches of your intent would help us to understand where the flare would be located.  If located on the outlet as part of the bellmouth, then one of the images in this thread suggests it would be beneficial: http://www.jpthien.com/smf/index.php?topic=550.0

I think that a 1/2" radius router bit and a 3/4" stock end flange 2" larger in diameter than the outlet would be good enough for our purposes.  Bell mouths that are too large risk pulling in dust from the sides of the drum/tophat, defeating the purpose.  Haven't been tuned in lately to see if anyone has done that, but I can't recall ever seeing it on this forum.  Of course, I am still a newbie...

Quote from: shorthanded on August 19, 2020, 01:36:11 PM
no pictures , i an still in the thinking stage. I got the idea on a post here my RBOETCHER. I want to eliminate the plastic bag most use when they switch from the two bag system to the wynn filter and the plastic bag. shorthanded

If you eliminate the plastic bag, you will be emptying the bucket frequently.  I tried using a baffle in this dust collector and it vibrated something terrible.  The ramp had been shortened a bit.

Then I removed the ramp altogether and added the plywood ceiling and it worked much better with minimal vibration. The ramp is not helpful if you want to add a baffle.

Many people have built successful separators over the years and are happily using them.  There may be fewer people building, experimenting and tuning their separators now than at other times of the year.  Activity always seems to pick up in the fall!

For your question, look at this post:
http://www.jpthien.com/smf/index.php?topic=1109.msg6086#msg6086
I am still using my "temporary" Penn state DC-2, 1.5 HP dust collector.  Spiral ramp has been removed, baffle and plastic bag below the ring, over-sized felt filter bag above the ring.  There is also a plywood ceiling with a coffee can chimney that allows air to flow up into the filter. I'll look for photos this evening.

The spiral ring is designed to deflect airflow, chips and sawdust down into the lower filter bag on this model.  With a Thien baffle, you want the solids to drop down into a space that is a dead-end for airflow.  The airflow must then be up and away from the solids.

Does your collector have one bag above and one bag below the ring?

That planer has a 2.5" blower discharge, so you have already up-sized to 4", which reduces your velocity.  Increasing the outlet diameter to 6" would reduce pressure drop, but it is a very short length, so there might not be much benefit and the risk of increased bypass is a reason not to do that. 

If you are inclined to mess with success, consider eliminating the 90 degree ell at the separator inlet. OTOH, if it's working well, declare victory!

Quote from: retired5 on February 17, 2018, 06:53:36 PM
These systems always run by applying a vacuum. Can anyone tell me if the reverse is applicable?
Can you run the powered exhaust from a DeWalt 735 thickness planer into this system?  With, or without using something like an enhanced Harbor Freight collector?

Yes!
Use the Search function and you will find at least one system for the Dewalt planer that does not use an external blower - just the planer's internal blower. Here is a good one:
http://www.jpthien.com/smf/index.php?topic=809.msg4539#msg4539

I can't recall reading any discussion on the position of the drop slot in relation to the inlet on double-height separators. 

In single height separators, the slot begins 120° after the inlet and continues around until ending just before the inlet.  In a taller separator, the dust will drop to the level of the baffle and slot much later, after spinning around the perimeter of the separator some distance.  Should the position of the solid portion of the baffle be changed based on this? Does it matter where the slot begins in this case or is it enough that it is present to de-couple the air below the baffle from the air above the baffle?

I'm raising this question because your steel sides will not allow you to observe the separator in operation, and if it does matter, it would be good to be able to change the position of the baffle.

Dusty,
The spiral ramp is not helpful because it forces both air and sawdust down onto the baffle, through the slot and into the collection bag, where you don't want much airflow.  I found that it also caused the baffle to vibrate. 

This was discussed previously here:
http://www.jpthien.com/smf/index.php?topic=1118.0

My Penn State 1.5 HP collector had a spiral ramp and I removed it.  The system is much quieter without the ramp.  I have a large coffee can set in the upper plywood lid as a chimney.  It's definitely not optimal but it works for now.
-Dan

R2,
On behalf of everyone, thank you for making the substantial effort to preserve your photos on this forum.  A picture is worth a thousand words.
-Schreck

"1 - how much does it matter if the 6-inch hose enters the Top Hat close to the center vs the top
2 - the area of a 6-inch circle is 28.25 square inches
The termination of the HVAC boot is 40 square inches
How important is that difference?"

1 - If "close to the center" refers to the vertical dimension, then that should be okay.  I don't recall much discussion about the merits of entering a double height top hat at a high vs. low point.  Lots of warnings about trapping shavings between the transition and baffle, though, so leave a space between them.
2- the HVAC boot is a transition from a small cross-section hose to the much larger volume of the top hat, so the fact that the rectangular end of the boot is larger is good.  The primary purpose of the transition is to direct the air and dust flows to the perimeter of the top hat, which it will do.

Kind of quiet over here.....
Regarding the bottom plate, it should be located within the separator and not extend down into the collection barrel.  You want to keep the spinning air in the separator, out of the the barrel.  I think locating the bottom plate an inch above the bottom of the separator walls would be about right.

Nico, it sounds like the noise is being generated in the blue flexible hose.  Be sure to use a hose designed for vacuum, not one intended for water. 
Some hoses will set up a nasty resonance when the airflow reaches a certain velocity. 
This has come up before:http://www.jpthien.com/smf/index.php?topic=1191.msg6966#msg6966
Let us know what you find.
-Dan