Building my own Separator with 55gal drum

[chaosdsm]

I am a hobbyist woodworker & have been using a Shop-Vac for dust collection.  Added a Dust Right separator a little while back, but unfortunately, my Shop-Vac died the weekend before 4th of July. 

Fortunately, I found a Grizzly 1.5hp wall mount DC with HEPA canister filter on sale & purchased for a little over $720 shipped to my door!!! 



But, I don't like having the impeller exposed to incoming dust, dirt, wood chips, etc...   I also don't like the idea of stepping down to the 2.5" inlet/outlet on the Dust Right. 

So I've decided to build my own Thien Baffle separator.  I went to Rural King & bought a cleaned & refurbished 55gal drum, then found a cap style lid on Amazon. 



My plan is to use 6" fittings to tie into the drum lid, then put a 4" side collection into the drum.




Obviously a work in progress, I'll use Silicone sealant, galvanized repair mesh, and bolts to secure the 4" boot to the drum & seal up any leaks around it.

But I got to thinking.... would I be better off putting the baffle just below the inlet as everyone else does, or would it possibly work better if I installed the baffle just at the top of the inlet? 

Seems like if I were to put it on top of the inlet, it would physically block some of the finer dust particles from entering the 6" duct.   

Has anyone tried anything like this?  If so what were the results???

I'm also thinking of cutting off the tongue off of the baffle, then re-attaching it with a piano hinge.  Then all I have to do to empty the drum is remove the top, flip up the tongue of the baffle and empty the drum.  Any thoughts on this? 

[chaosdsm]

Got quite a bit of progress made since first post. Hard to believe it's been 3 months...



Here's my idea for the hinged tongue.  This would allow me to mount the baffle in place & leave it, while still having an easy way to empty the barrel when it's starting to get full.  Since I made the baffle and lid separate pieces, this seemed the easiest thing to do.

For the first setup, I have placed the baffle above the 4" port.  The thought being that with the airflow being under the baffle, the baffle itself will block some of the smaller particles from going up and into the DC. 


A lot of the work was preparing the 6" rigid duct & figuring out where exactly to place everything.  HVAC duct was used as it's cheap and readily available.  It's also really easy to cut with my Bauer battery powered metal cutting shears!  All seams are coated with duct sealant, then topped off with Aluminum HVAC tape to ensure no air leakage.  Even sealing the gap where the duct and DC come together. 


I used stainless steel rivets (since I already had them but no galvanized rivets) to connect all the ductwork together. 


These are mostly only sealed on the outside, but they got 2 layers of fiber reinforced DP 1030 mastic + 2 layers of tape on each rivet. Where I could easily access both sides, the inside also got a layer of mastic, but no tape due to the amount of rivet head that was sticking out.
 


For the 4" connector, I riveted it in place from the inside, leaving the long heads on the outside of the drum for easier sealing inside & out. 


The longest process was actually figuring out where to locate the drum in relating to the DC,  I ended up moving the DC twice & re positioning the drum 3 times to find the best solution!  In the end, I put it next to my big roll-up door which has a somewhat recessed corner, so there's more room inside my workspace. 



Everything is metal to metal, even my 4" duct has a continuous steel spring inside that will allow for easy grounding, so no worries about static buildup!

To seal the drum and drum lid against air leakage, I put a 1/2" thick x 1" wide ring of closed cell foam around the area that sits on the drum rim, then I stuffed 25 feet of 3/4" closed cell backing rod between the side of the lid and the side of the drum (with an average gap of about 1/4 inch) which ended up being just over 3 full loops around the drum. 

Some basic testing has shown me that I get a least 580 CFM of airflow at the 4inch connector, and that I need a better anemometer that can read more than 67MPH airflow. 

The Grizzly 1.5HP DC is rated at 1250 CFM, and I'm guessing that the actual airflow at the 4" connector is closer to 700 CFM, possibly higher.  But it'll probably be a few months before I get a better meter.

[chaosdsm]

Picked up a better anemometer, and with the baffle set above the 4" barrel collection fitting, I'm getting a reading of about 946cfm.  After about 2 hours of cutting mostly 3/4" hardwood plywood on the table saw, my collection bag under the filter canister is completely empty! 

Will be doing some finish sanding (220 grit) on the drum sander in a few weeks.  That will really show me how well this setup works.