J. Phil Thien's Projects

I built my 'top hat'- style separator several years ago... when they first appeared on this forum. I consider it very good when it comes to separating the dust, which is important because I have a Wynn pleated filter that isn't equipped with a shaker paddle to dislodge dust that becomes embedded in the pleats.
I'm now questioning the overall effectiveness of my DC doing it's basic job which is to intercept and collect dust from my woodworking equipment. I've read somewhere in the myriad of threads and info that the top hat separator introduces @ 30% loss in air flow. Does that reduce the air flow to an unacceptable volume? I'm pretty much on the fence at tis point.
For the last while most concentration has been on 'top hat' design. Any thoughts on it's performance vs a straight baffle design in terms of a) ability to separate dust and b) impact on air flow? Does the simple baffle design flow more?

I'm working with a Delta 50-760 equipped with Wynn poly pleated filter and 10' length of clear 5" dia flex hose. My table saw has 1- 5" port. I move the DC from machine to machine as necessary.

Has anyone measured the actual loss/difference in air flow resulting by inserting the separator into the loop for the various configurations?

In most cases I've seen documented where the separator is used as a "pre-separator", it's located upstream but pretty much beside the impeller. Has there been any work done to determine how moving the pre-separator further upstream affects performance?
Occasionally, locating it nearer the dust source might be possible, in fact desirable, or perhaps some might choose to locate the DC equipment in a separate adjoining room, closet or perhaps high on a wall but want the collection pail to be conveniently located for frequent emptying etc, or just because of space considerations.
I expect the pre-separator does impose a certain amount of loss, but on the other hand, the clean air will be somewhat more easily propelled than dust-laden air. 

I made this 'top hat' design mostly from scraps lying around the workshop.
The top and bottom plates are 1/2" plywood, cyclone window is @1/8" acrylic ( strong and flexible). "in and out" ports are 5" dia-26 gauge galvanized HVAC pipe, dust slot is @ 1 1/8" wide and 240 degrees. Rather than using bolts to clamp the sandwich together I used 5" tall 'legs' with screws from the top and bottom plates. These legs butt up against the acrylic (which is set in dados) to give it more strength and rigidity. Initially I set the acrylic in a bed of latex calking in the dados but found the latex didn't adhere to the acrylic very well so I applied a liberal bead of 'Goop', an auto weather stripping sealant to the outer edge of the acrylic and it forms an air-tight seal. The upper lip of my old rubbermade garbage pail was pretty rough so I added an outer ring of plywood to the underside of the base plate that sits snugly against the outer dia lip of the pail and also a bead of rubber weather stripping to the mating surface of the underside of the lower base plate. This forms a near-airtight unit once the DC is running.
The total out-of-pocket cost to me was almost nothing and @ 3 hours time to build the unit and give it the fancy paint job.
It sucked up 10 gallons of mixed shop dust with no perceptible dust escaping the pre-separator.
I'm very happy with the performance so far and can highly recommend it. Thanks Phil and the others here who developed and enhanced the concept.