J. Phil Thien's Projects

Cool this is exactly the kind of info I was hoping for.  Since I'm still playing with a shop vac as my vacuum source I'm thinking I can make the interior of my "top hat" just a little bigger than the 2.5" hose that I'm using.  Using a standard garbage can I ought to have a very nice outer diameter and the relatively thin top hat chamber ought to keep the swirl spinning nicely.  I'm also going to experiment with using a subtle spiral as my interior wall in an attempt to make the air flow as uniform as possible with the new air being brought in through the inlet.  The idea is to introduce the new air into a stream of "cyclone" air such that they meld at the point where the two streams would be parallel.

Does anyone have any opinions about the slot portion of the design?  In the original design the bottom baffle was made out of 1/8" hardboard.  I assumed that was because a thin baffle allowed cleaner airflow into the bottom of the chamber while the baffle itself kept most of the material in the bottom chamber after it had passed through the slot.  I would assume a thicker board would cause more turbulence in the airflow.  But wouldn't it also help to isolate the aircurrents to above the baffle?  Taking the concept to the extreme, what would happen if I had a really thick baffle (like 12" thick)? 

Which leads to another question...

I can see how we would want air flow as smooth as possible in the upper portion to keep particles thrown to the outside edges until they get a chance to fall, but what about the bottom portion below the baffle?  Wouldn't it be a good idea to try and slow down/disturb the airflow below the baffle to give paticles a chance to fall out of the stream?  I'm thinking of an inverted cone so as you fall deeper the diameter is larger so the velocity is smaller so more particles fall out of the stream, or an angled guard that diverts air below the baffle away from the drop slot making it harder for air to recirculated back in to the incoming stream from below the baffle, or even just some vertical bars installed below the baffle to with the intent of to trying to disrupt and cancel air currents below the baffle.

Thanks for the advice and the great idea.

Is there any advice about the height of the chamber in a "top hat" design?  I know Phil's rule of thumb about the outlet pipe extending by its radius into the chamber from the center of the chamber.  I also know the preferred air flow is parallel to the top and bottom plates of the chamber (with the bottom plate being the baffle of course).  Should I shoot for a chamber that is the height of my inlet pipe diameter?  Is taller better?

Almost all (I only say almost because I might have forgotten one) of the baffles I've seen posted here have used the diameter of the drum or bucket as the diameter of the baffle and lid construct.  I've been looking at the "tophat" design and wondering if there is any reason to do so?

With the tophat design it would be fairly simple to create a Thien Baffle Chamber with a smaller diameter than the opening of the container being used.  This of course assumes you have room to mount your hardware (there is of course a lower limit to how small you can make the chamber, right).  But you could also go in the other direction with a little bit of planning and make a chamber bigger than the diameter of the container being used.  Given the ingenious things I've seen done, I'm sure going either way is well within the realm of feasible modifications.

So has anyone given any thought as to what works "better" from a chamber diameter point of view?  Is a small diameter chamber better at accellerating small particles against the walls thus pulling more fines out of the stream?  Does a larger chamber allow more time  bumping against the wall and a greater chance to precipitate due to a longer drop out slot?  ???

I built my first "quick and dirty" seperator and I'm very happy, but curiosity has got me thinking about this "tophat" design.

-MunchyMonster

I've been cutting mdf on a cnc machine and I was clogging the filter on my shopvac in less than a 1/2 hour of cutting.  I had seen Phil's design on CNCZone and decided I would try throwing together a 5gal pail version.  I didn't see the plans but had read an article about the basic principles.  I designed a bottom plate with the 240 degree cutout to fit the pail I had available in my shop (an old 5 gal paint pail), and worked up the rest of the parts (plumbing elbows, 2 1/2" hoses, etc.). 

I hadn't seen any specs about the width of the drop slot so I completely guessed.  I think my drop slot is about 1/2 inch.  Is this way too narrow for a 5 gal pail sucking fairly small particles?  I'm cutting MDF with a router and while I'm getting decent sized "chips" we all know how MDF likes to disintegrate into a fine powder.  Even my big chips are in the 1/4 - 1/2 inch range in rough diameter. 

I don't appear to have any clogging issues that I can detect.  Is my drop slot sufficient?

-MunchyMonster