Retrofitting a Laguna 2-stage cyclone dust collector with a Thien baffle

[mhrobus]

Hello all-  I am posting this because it seems a bit different than most of the builds on the forum, and the subject of improving performance of 2-stage cyclone dust collectors doesn't seem to be covered here very much (based upon searches and reading through posts).

Shortly after receiving my 2 hp Laguna 'cyclone' dust collector, I realized that it had a bad 'scrubbing' problem (whirling of chips & dust in the collection bin so that they would re-suspend in the vortex, be carried up through the impeller, and then be deposited in the final bag under the filter).  I found that I could turn on the machine and without collecting any new dust, could hear it picking up stuff from the bin (lots of rattling) and throwing it over into the final bag.  Having paid a lot of money for the thing, as well as having to pay to barge it to Southeast Alaska in addition to regular freight costs, I was not happy – the whole reason I bought a 2-stage cyclone DC was to collect chips & dust without pulling them through the impeller!

Having run into the Thien baffle concept on the web, it occurred to me while regarding my machine with a jaundiced eye, that there was an opportunity to insert such a baffle into my machine just below the intake (a side intake tangential to the barrel of the collector body) and just above the cone leading down to the collection bin.  I had some concern that the outlet from the separator extended downwards too far, and worried that this would "grab" chips & dust before they fell through the slot around the edge of the baffle.  However, I decided to give it a try and cut up a leftover piece of ½ -in MDF into a baffle of the proper diameter and with a 1 1/8 in slot around 240 degrees of the perimeter.  I hung the baffle using 3 pieces of all-thread and nuts, washers, and lock washers from the top bulkhead of the collector barrel, and firmed up the baffle with a couple of screws through the side of the collector into the edge of the MDF.  I sanded the lower edge of the slot to minimize any obstruction to debris falling through the slot.  The hardest part to this fairly casual conversion was to manhandle the heavy 2 hp motor and impeller assembly off of the top of the machine so that I could flip the barrel upside down to work on inserting the baffle.

Once I reassembled the machine and turned it on, the first thing I found was a surprising reduction in noise – I can only surmise that the baffle screwed to the side of the collector body helped damp vibrations, and the reduced disturbance down into the collection bin has stopped all the rattling in the cone & barrel.  More importantly, the DC no longer scrubs the material already lying within the collection barrel, so that no (very little) material is being sucked through the impeller.  Although I cannot see the baffle in operation due to the metal sides of the collector, I seems as though the baffle is de-coupling the vortices above and below it (like it's supposed to), and it appears that I am no longer getting large amounts of chips & dust through the fan.  The final collection bag under the filter has not filled nearly as rapidly as before.  Suction to my collection ducting is still fine.

Although I approached this as a rough-and-ready first approximation, I believe that for now the new baffle is all I need to make this 2-stage collector run the way it should have in the first place.  My next plot is to try to sound-deaden the exhaust duct from the impeller to the final filter and maybe to try an 'air-straightener' in the separator outlet (impeller inlet) to increase efficiency and reduce noise.

Thanks to Phil for coming up with the baffle design and sharing it with the rest of us!

I'm including 2 photos – one of the DC installation and another showing the MDF baffle as I installed it (you're looking at the bottom of the collector, tipped upside down).  If you have a 2- stage DC whose design doesn't prevent by-pass through the impeller, I suggest you consider inserting a baffle like I did -- it makes it work a whole lot better!


-Matt

[johns-mpls]

Very nice!