Question about my baffle

[dbdors]

New to the Thien baffle.  Built my first one this past weekend.  I used a 30 gallon fiber drum and 1/4" Birch plywood baffle.  I used a 5" flange connector from Oneida to connect the drum outlet directly to the DC, a Delta 50-760 (which has a 5" inlet).



My question is about the inlet of the outlet.  This question was asked in another thread, but no answer was given.  My question revolves around the inlet to the 5" flange.  Many people use a 4" outlet connector, and that 4" pipe protrudes inside the baffle area.  My design does not.


I have an idea for a short piece of duct from HD that I can add, but don't want to do it if it adds no value.  So far the baffle is working well.  I dumped out a cubic foot of dust that I had and there was maybe 1/4 cup of carry over.  And some of that may have come from the dust bag.  Does the design need/require that the outlet tube protrude down into the baffle area.  If yes, how much?  I've seen some with protrusion and some without. 

Also I installed a Wynn filter this evening.

You can see some pics of the set up here: http://www.pbase.com/dbdors/dust_collector_mods

[alan m]

yes you definitely need the out let inside the separator . make the pipe long enough so that it is half the inlet diameter above the baffle

[dbdors]

Thanks, so I'm clear on the need to drop the outlet pipe into the baffle area.  But when you say half the Inlet diameter which inlet are you referring to. 

I should clarify, I have a 4 inch hose feeding into the drum.  And a 5 inch outlet feeding the dust collector.

Did you mean inlet of the drum or "inlet" of the 5 inch flange?, (inlet of the outlet pipe?). So should I drop a pipe 2 inches or 2.5 inches from the baffle?

[alan m]

the inlet into the seperator

[retired2]

Thanks, so I'm clear on the need to drop the outlet pipe into the baffle area.  But when you say half the Inlet diameter which inlet are you referring to. 

I should clarify, I have a 4 inch hose feeding into the drum.  And a 5 inch outlet feeding the dust collector.

Did you mean inlet of the drum or "inlet" of the 5 inch flange?, (inlet of the outlet pipe?). So should I drop a pipe 2 inches or 2.5 inches from the baffle?

You will not likely find any difference in performance between 2" or 2.5".  The benefit of the pipe protruding into the separator cavity is that it pulls the outgoing air more from the floor of the separator.  This helps pull the centrifigal waste stream down to the drop slot.   In your current setup, you are pulling too much of the outgoing air from the ceiling.  This pulls the waste stream up away from the drop slot and that contributes to excessive bypass.  Frankly, I'm surprised you are not seeing more bypass than you noted.

If you drop your outlet pipe lower into the cavity,  I think you can improve on your 1/4 cup bypass per 1 cu. ft.

[dbdors]

Thanks, I went to HD earlier for some 4 X 24 aluminum vent tube.  Cut about 8" off the crimped end of each.  Combined the two pieces, then cut it down to the diameter to fit inside the flange.  Taped it with some aluminum vent tape that I had.  Was planning to pop rivet it, bit tape is working well.  A little hot glue to hold it in place.  So working well it seems. 

[alan m]

report back how its performing  after a good run of dust

[retired2]

Thanks, I went to HD earlier for some 4 X 24 aluminum vent tube.  Cut about 8" off the crimped end of each.  Combined the two pieces, then cut it down to the diameter to fit inside the flange.  Taped it with some aluminum vent tape that I had.  Was planning to pop rivet it, bit tape is working well.  A little hot glue to hold it in place.  So working well it seems.

If you decide you want to squeeze a bit more performance from your setup, you might want to consider adding an air-straightener and a bell mouth inlet.  You are using the same Delta DC as I am, and a very similar set up other than the rotational direction of your separator inlet.  Those two additions will probably not improve your separation, but they will improve your CFM throughput and possibly your noise levels.  I would not bother with either of these if your DC is intended to remain portable and moved to each tool as it is being used.  But if it will remain stationary and be piped to each tool with blast gates, you will want tp get every CFM you can.