J. Phil Thien's Projects

First of all, thank you to Phil and all who have contributed to this baffle / top-hat design.  I've borrowed/stolen many ideas from several of you (especially retired2) to put together my separator, so thank you.

I finally finished enough of my tophat system to give it a test run.  The results were mixed - I think there's still some tweaking to do.  I ran it without the filter and only see bypass if I put a lot of dust through at a time...more than would typically come from a machine, I think.  The odd thing I see is that a lot of the dust goes up and spins around the top of the chamber instead of being pulled in a spiral down to the slot.  My separator is 12" tall with the bellmouth 3" from the bottom.  The inlet is 9.5" tall by 3.5" wide and is flush to the top of the chamber.

One thing I see is that the hardboard baffle, though partially supported with plywood beneath, is being pulled up by the suction in the chamber, so I wonder if that's creating an upward air ramp (or maybe it's the result of something else pulling air upward).  I will probably try adding a dowel or threaded rod to keep the baffle from rising to see if it helps, but if anyone has seen this before and has ideas on fixing it, I'd appreciate the input.

I've attached a few pictures of what I have so far (haven't attached the filter and clean-out yet).  I didn't take photos at every step of the construction, so the pictures don't show everything, but the general idea is there.  I did make a bellmouth from plywood/mdf and the largest round-over bit I have (3/4 R) and added T12/T8 bulb protectors to the outlet for air straighteners. 

Yes, that's my general idea, going directly from the blower to the filter without a second ring.  The filter is not in a box by itself, the box idea was to enclose everything for sound deadening, but I may not pursue that idea.  I'm working slowly on it when I get a few minutes here and there - have the round to rectangle transition done, all the tophat components cut out, and will hopefully get the tophat assembled in the next day or so.  One thing I'm pretty positive about is that my original notion of making the tophat out of the DC ring would have been a LOT less effort.  I guess I've learned a bit about cutting out circles, though...including using the smallest diameter bit to cut down on the wood/mdf/hardboard dust flying around.  It's pretty ironic the amount of dust I've created making something to collect dust.

Thanks everyone for the inputs.  After doing a bit more reading about what makes a good top-hat design, I'm becoming convinced that I shouldn't use the dc ring - mostly because of the 6" round inlet that would be blowing in only 1" away from the 6" outlet, making bypass much more likely.

So, my plans now include making a top-hat with a 6" round to 8"x4" transition (13% larger cross-section for the rectangle).  I would make the rectangle taller and narrower, but that would increase the height.

I'd like to have the outlet at least even with the bottom of the inlet, so the tophat should be 11-12" tall.  With a 1.5H tophat, I recall some issues with bellmouth outlets (Mike F http://www.jpthien.com/smf/index.php?topic=1110.msg6292#msg6292), so I'm leaning toward a straight outlet with air-straighteners (t8/t12 bulb protectors).

I see that Retired2's tophat is 1H.  Is there any evidence that other than height, there is any drawback to making the tophat taller than the inlet?  I guess if I wanted to make the rectangle of my transition taller and narrower, I could make the overall height the same or slightly taller than the inlet.  I wonder which would be better...a 12" TH with an 8"x4" inlet or a 10" TH with a 10"x3.2" inlet?

As far as enclosing everything for noise-reduction, I'm going to try it without enclosure first and see how tolerable it is (I haven't had DC before, just recently picked up the used delta unit).  I may try an insulated hvac duct from the blower to the filter for the first step in noise reduction.

QuoteYou will be very surprised as to how much air the unit needs. I enclosed my air compressor in an area about 3x3x10 and installed a vent and fan to ensure it did not get too hot after using it quite a bit one day without the vent. The fan comes on when the air compressor comes on. Do the same for your enclosed unit.

If I do end up enclosing, this was my concern.  However, the case of an air compressor vs a DC is a bit different, since the DC pulls ambient air into the box and if it flows across the motor, it should act like a very strong fan (or so my theory goes).  We'll see if I ever test that theory.

Thanks again for the ideas and thoughts... this site makes for some interesting reading on a topic I've never thought much about before.

Thanks for the replies and ideas. 

My intent on attaching the blower would be to close off the 11" opening in the inverted cone inside the delta ring, then use a 6" duct straight up to the blower inlet, much like TX_Lenador did in http://www.jpthien.com/smf/index.php?topic=1054.0 .  I'm not sure how that cone would affect the airflow or separation, though I recall Phil saying that people have had good success using the dc ring as a top-hat.

I'm not opposed to making a separate Thien top-hat, but I thought if the delta ring worked as well as a self-made top-hat, it would be a lot less work - already have the 6" side inlet and 20" diameter cylinder, just need to cut some circles.

I'd like to keep the airflow as high as possible, so having two rings (a Thien top-hat and the delta ring) seems like it would restrict flow.  If I can get rid of one of those and go directly into the filter, that seems better to me for airflow.  The only caveat would be if the air forced into the filter slams into the bottom of the filter and creates turbulence.  I don't know if that happens or not, but the design seems to work fine with cyclone systems.

The enclosure I had imagined is made of 2x4s with insulation between, peg-board (rough side exposed) to the inside and something (homasote, maybe) on the outside.  To keep it from back-pressuring the system, is there a rule-of-thumb for sizing the vent?  I agree that if the vent has to be large, it defeats the purpose of the box.

dabullseye, I had the same thought about putting french cleats on the enclosure.  I try to make things do double duty in my garage if possible.

Hi all,

I'm trying to design a DC system using my Delta 50-850, top-hat style separator using the drum from the 50-850, and Wynn filter (still to be purchased).  Ideally, I'd like to put all of it in a sound-insulating enclosure on wheels that will take up as little space in my half of the 2 car garage as possible (floor space especially, but also vertical, as I could place it under a lumber rack if it's short enough).  I know that having it in an enclosure could be bad for overheating the motor, so I thought to place a vent near the motor but opposite of the cartridge filter so the filtered air would pass across the motor to cool it.  Has anyone tried something like this or have any concerns about the idea?

My second question is about the air after it leaves the blower and goes to the filter.  If I made some sort of a box between the blower and filter instead of using flex pipe, I could use the narrower Wynn filters and not have a tight corner.  If the volume of the box was large enough (not sure what "large enough" is yet), would the air flow at that point matter, or would it just be depressurized air?  And, does the shape of the interior of that box matter - should I make it rounded in some direction?

Finally, if I remove the restrictor ring in the 50-850 and only connect to a single machine via 6" flex pipe, would I risk damaging the motor with the configuration I've described?

Thanks for the help in advance!

Hi, I'm an engineer by day, occasional hobbyist woodworker when I can stop over-analyzing and designing projects.  I'm currently exploring ideas on how to make an efficient separator/filter occupy as little space in my 1 car garage as possible.