J. Phil Thien's Projects

Occamsbeard, it depends on what you mean.  I think you mean you'd have 1 circular chamber that is divided into two sections.  The top section will be a conventional impeller chamber with a side outlet and the bottom section will be a conventional thien baffle separator with a side inlet and a drop slot at the bottom and a ceiling with a hole in the middle.  I think that would work ok if it made the construction simpler.  That said the impeller chamber is usually a scroll where the outer wall is following a path of larger and larger diameter as you trace around the circumference.  The separator chamber is usually circular with a constant diameter.

On the other hand, if you're talking about a single chamber that has an impeller inside and a drop slot in the bottom then I'd agree with Retired, that wouldn't work.

So, please explain more what you have in mind.

Hey Retired, thanks for commenting.  The elbow on the output is part of the original drum top collector equipment.  I concur that a longer sweep elbow would be better but I don't have the vertical clearance under the filter for a longer sweep.  Maybe if I elevated the drum onto a drum dolly I could make it a longer sweep.  In short though, it was the lowest barrier to use what was already there.

Regarding the inlet, I biased the inlet as high as I could, but you're right that for the most part it's putting most of the material in near the midline.  I thought about making the input transition shorter, say 3.5x8"so I could at least be putting the air into the top 2/3, but then I'd be restricting airflow to some extent as the area of the inlet would be less than the input 6" duct.  I decided to go with what I thought would cause the least restriction to airflow.

I thought you'd find the following interesting though.  As I mentioned, this is a Cincinnati Fan designed and build unit.  Not only do they not include a flow straightener in their own unit where they are close coupling a blower, but the direction of circulation they impart via the input elbow is the opposite direction of what the blower turns.  Granted, they have the rotation in the barrel pretty messed up with the intake shroud blocking the rotation so maybe the rotation is largely negated.  In the manual it does state that the intake shroud has to be in place or it will GREATLY (emphasis theirs) reduce the CFM of the unit.  I wonder if this is because if the shroud is absent then significant rotation will take place in the barrel which will then be running counter to the blower rotation.

Hey Benard, thanks for your comments.  I think you're right that a longer transition from round to rectangular would probably be better, but the fact that the shorter one was compact, inexpensive, and off-the-shelf was pretty compelling.  I suppose it could be broken out of the existing housing as it's epoxied in, but that's not in my short term plans.

I think the 90 degree turn to make the filter vertical is worth the static pressure cost as it allows me to have a catch basin at the bottom to catch dust dislodged when cleaned from the outside with compressed air as Wynn suggests.

The slot is a 1.25" wide drop slot.  I haven't seen anything get caught at the end of the slot yet but perhaps I haven't made the problematic type of shavings yet.

Well, the black hose you see in the picture is the 5 feet of 6"  hose that came with the drum top collector.  I bought 20 feet of clear 6" flex hose from Amazon, the Woodstock 1036, but if I had to do it again I think I'd just buy 25' from Wynn Environmental.  What they call 10' is actually 6 1/2 feet laying on the floor.

I was able to get the 6" flex hose to stretch over 6" ASTM 2729 sewer and drain 6" PVC so I've got a 6" PVC female bell at one end of each of my 10' sections and a piece of 6" straight (male) at the other end.  That enables me to just quick connect to whatever length I want.  I use a piece of 6" straight pipe as the tool port at each of my tools so I can just plug the hose with the female PVC end onto it.

I made a plywood form so I could make those female bell ends out of pipe whenever I want by heating the pipe with a heat gun and pushing it onto that greased form.

I finished a tophat build that started with a 55 gallon drum based dust collector that Cincinnati Fan sells as the model 200s, see pic below, as a 2 stage collector.  It had a 2HP Leeson motor with a 12.25" impeller and 6" inlet and outlets, which was an ok start, but its separation characteristics left a lot to be desired.  It scrubbed the contents of the drum badly and passed about 1/3 of what went into the drum on to the filter bag.  The manual even said to empty the drum when it was 1/3 full or it would start filling the filter bag faster. The bag was a 18 square foot bag of 5 micron knit polyester.  I attached a photo below of how the underside of the drum lid was designed.  There was an elbow on the inlet which would have started a rotational motion except there was also a big 10" diam shroud on the underside at the outlet that was up against the drum side, so any input air would have only gone 1/4 turn before hitting that shroud.
So, I figured this thing could really benefit from a tophat that would do a good job of separation, allow what went into the drum to stay in the drum, and that would enable putting a better filter on it since you'd no longer be sending everything to the filter.
I went with a design that didn't deviate too far from what others have shown on this forum.  My 6" round inlet hose transitions to a 3.5" x 10" rectangle using a floor register from Home Depot.  The body of the chamber is 12" high, so the body is either a 2X high tophat based on the diameter of the 6" inlet, or 1.2X high based on the height of the rectangular inlet.  Anyway, there is 2" of full circle that passes under the inlet rectangle.  I used 0.093" (3/32") PETG from McMaster Carr.  24x48" sheet was $26.  The PETG is very flexible and was easy to form into the tube to go inside the rings.  The interior space is a 21" diameter circle and the outside dimensions of the wooden rings was 24".  I epoxied the PETG into the plywood form and then used silicon caulk  around the outside to ensure a good seal.  The outlet at the top of the separator is a 8" to 10" reducer also from Home Depot.  It further tapers to 7" as it goes into the impeller housing.
I had some 3/8" plexiglass that I'd curb picked that I used to make the actual baffle.  By using clear material for both the sidewalls and the baffle I'm able to look through the side down into the drum and see how full it is directly.  Around the top of the tophat I've got 3 hoist points and I have a 7:1 block and tackle pully I got from Amazon for $14 that I can use to pull the entire tophat up off the drum and tie off with a cleat.  Inside the 55 gallon drum I've got a 55 gallon bag taped.  When the bag/drum is full I'm going to nylon zip tie it closed and tip the drum on its side and pull the bag out.  Haven't gotten that far yet as I haven't yet filled the drum the first time.
I used the 0.5 micron 300 square foot media 9L300NANO filter from Wynn Environmental.  I made an interface flange for it out of plywood and added a gamma lid ring to the bottom of it with a 5 gallon bucket cut off at about 6" so I've got a screw on dust basin at the bottom of the filter.
The entire collector is free standing on top of the drum, which I think is a nice attribute because I can scoot it around if I need to.  Right now I'm just running 6" flex to tools as needed as I don't have 6" ductwork up yet, but you have to start somewhere.
It seems to work really nicely.  Thanks to all the folks that posted their builds before me on this forum.

Does anyone know a source for 6" PVC 2.0 or 2.5 R/D 90 degree bends for SDW pipe (6.275" OD)?  I've found metal long sweep 90s but not PVC.  Thanks in advance.  If I can't find any I may take a stab at making some.

I thought this brochure of cyclone dimensions for various sized models was pretty informative in terms of sizing dust separator barrels, inlet sizes, cfm, and motor sizes.  I'd like to know what folks think about me using these as sort of rule of thumb guidelines for how to size the drum/baffle, inlets, etc.

Kind of putting together the pieces that I thought was useful is summarized in the table below

Diameter-------cfm------motor HP-----inlet size
12 inch--------300-500----3/4 HP-----4 inch
16 inch-------800-1200---2 HP--------6 inch
20 inch------1200-2000---3 HP-------8 inch
24 inch------2000-3500---7.5HP-----10 inch

I bring this up because I've got one of these Cincinnati Fan model 200s 2HP 1100 cfm barrel top collectors on a 55 gallon drum with 6" inlet.  I was thinking about adding a side inlet and a baffle to the barrel so it would have a 24" diameter inside the barrel for the separation chamber.  I am thinking now, based on the table above, I'd be better off making a 16" diameter tophat with a side inlet so I get the higher rotational speeds at the cfm range I'm at.  I'm thinking that for a given inlet airspeed a 16" drum is 50% higher rotation rate than a 24" drum, just based on the distance around, hence the need to match the vessel diameter to the CFM coming in.

Maybe as more of a direct question, is there a target rotation rate we are trying to achieve, which could be arrived at via linear airspeed at the inlet and drum circumference?

I've been reading a lot about the Thien baffle and debated whether to make a Thien separator to go underneath the 2HP Harbor Freight Impeller/Motor or to put a Super Dust Deputy under there.  I went with the Super Dust Deputy because it is plug and play but my impression is that the performance is about par with a Thien separator.  I'm putting in a Wynn cartridge instead of the Harbor Freight 5 micron dust dispersal bag and I'm interested in whether or not a Thien baffle inside the filter ring would be wise, used in conjunction with the Super Dust Deputy pre-separator.  Would it result in less dust making it to the Wynn filter?  Would it reduce the CFMs being pulled much?

Fine Woodworking did an article called "Soup Up Your Dust Collector" or something a couple of years ago where they compared a Super Dust Deputy pre-separator to a Thein baffle in the collector ring, but I don't think I've seen anyone discussing doing both combined.