J. Phil Thien's Projects

I am planning to build a separator with 8in inlet and outlet to service a 3hp system - does anyone have any ideas on sizing for this size unit?

Bernard - I didn't seal the top the MDF and the Acrylic top fit very cleanly and I could see no signs of any leaking - I am thinking when I am finished playing around I will run a bit of silicon around the top - let it dry and then it would basically act as a gasket when I snug the top down.

Holbs it didn't take long to make up the bell mouth - but as I think about it I have accumulated quite of whack of tools etc over the years. So I didn't have to make anything or buy anything. Anyway here is what I did.
I laminated two thicknesses of MDF and then found the centre.
I drilled an 1/8" pilot in the middle to centre my circle cutting jig - I have a small one I made that I mount on a laminate trimmer
I cut the outside perimeter first and made it 2 3/4" larger than outside pipe diameter - but the way when I drill the pilot hole I drill it on the drill press so it is dead vertical and then you can cut from both sides and everything lines up where the cuts meet.
I then routed the centre out - on one side I routed about 3/8" deep to the circumference of the outside diameter then I flipped it over and routed the balance out to the inside diameter - this created a lip for the pipe to seat against and the bell mouth is flush to the ID of the pipe.
I have quite a pile of router bits and I used a larger round over bit and a chamfering bit to get close to the interior profile and a bit of sanding smoothed the profile
On the outside I just flipped my bandsaw table to about 40 degrees and cut it free hand and tidied up the cut with a random orbit sander. It really didn't take that long
These are the bits I used and my laminate trimmer jig --Good luck :)

I am making headway with the top hat. I made the top so I could easily remove it. I have played around with the height of the outlet in relation to the baffle and found about three inches off the baffle seems to give me the best results in terms of air flow. I didn't like the size of a manufacturer bell mouth as I suspect the wide flange could introduce a disturbance to the air flow. I made my own bell mouth from MDF and it only projects 1 3/8" from the side of the outlet yet it does basically shape a 45 degree angle which serves to reduce inlet pressure loss. The bell mouth does seem to relieve at least some of the loss through the unit.

Hi there  - nobody else with more experience than I seem to be jumping in here so I can give you my limited bit of experience - I am just getting a double high working - my dimensions are 13 1/2" high and 18" in diameter. I am finding the dust is making at least half a revolution to as much as 1 1/2 revolutions before it disappears - so though I am not positive but I am pretty sure it is going to work for you as it is.
Out of curiosity what is your diameter? I only have a 1 horse collector hooked up, with a 3hp collector I would be making the diameter as large as I possibly could. Depending how you are setting it up but you could possibly even go to a 24" diameter and install a tapered section to fit your drum below the baffle. A 55 gal drum is going to be pretty heavy when you get it full. I also found that installing a bell mouth on the outlet intake was a definite improvement. I just made one up from MDF. I played around a bit with height and ended up with the intake for the outlet above 3" above the baffle.

I'm not completed yet but I had to try the new top hat out to see if it is going to work, pleasantly surprised to see how the material spins out into the collection barrel. I have to try and figure out where the optimum position for the outlet is in relation to the baffle. One thing I have noticed is that there seems to be a very appreciable drop in air flow before and after the separator and I seem to recall retired2 mentioned this could be a fairly significant drop. What are people out there finding in term of loss going through the separator? I would really appreciate any comments.
I was able with my poor pea sized brain to make a short video of the separator which, if the stars all align, you make be able to find at the included link. :)
Thanks to Phil for this very interesting concept.

http://www.youtube.com/watch?v=P-oyF5klvNE

I'm working on a new top hat design if it works I really would like to thank Phil, retired2 and a few others on this forum. If it doesn't work then I am going to blame you for making my little furry mind spin in circles for the last few months. I think I have read most every posting on this site and have been very intrigued by this whole concept. A dear friend of mine turned me onto this concept and I have tried to incorporate a number ideas I ave found here including double height, rectangular inlet etc.  Anyway I am starting to get close to the end and thought I would share where I am right now. I have designed the sides with 1/16" lexan and the top with 3/8" acrylic. My intentions are to build a large unit for a 6" intake and outlet this one is going to be 4" in and out.