Starting planning for Thien Seperator for Shopsmith DC-3300

[bobgroh]

Present dust control for my small woodworking shop is a ShopVac with a Olympic Dust Deputy front end.  Works nicely but need a bit more capacity for 6" planner, lathe, etc. I was just given a used Shopsmith DC-3300 (doing some cleanup and rebuilding on it presently) and I definitely want some pre-filtering on it. The DC-3300 is a small machine - 330 CFM, 1/2 HP but does have good impeller design, is quiet and will run for long periods of time.  And it was a gift!  And free!!

After much looking and reading, I am planning on Thien design for a prefilter for my little DC-3300. Outline so far includes a 2H top hat design, 4" inlet and outlet, round to rectangular inlet converter, outlet air straightener, 3 vane deswirler and a top hat baffle on bottom. Not sure what to use for dust collection barrel or no specific ideas (yet) for materials, etc.  Any and all comments would be welcome.

[retired2]

i would recommend a Brute garbage can.  It's light, durable, and lends itself to a tophat separator design.  I'm not familiar with the DC-3300, but I doubt it has very high SP, so there is almost no chance that you will collapse that Brute can.  I've never collapsed mine with a much bigger DC attached.

I'm hoping you are planning to move the DC-3300 close to each machine, because at 330 CFM it will struggle to maintain the velocity needed to convey shavings and chips.  The 330 CFM rating is probably with nothing attached, ie no piping or outlet filter.  When you add a Thien separator, and a little bit of piping or hose, you will likely be down around 200 CFM.  Run the numbers to calculate the velocity in a 4" line at 200 CFM, you are probably going to be below the recommended velocities for conveying woodworking waste.  You might get away with it if your lines are short.

[bobgroh]

The 330 CFM flow rating does include an output filter - the standard one being a 30 micron bag.  Yeah, I know not very good in today's world. And, yes, this is a portable unit - at least in my shop it will be - it is basically designed to be used with 2-1/2" lines.  So I will roll it around to the various machines

The DC-3300 has a SP of 6 to 7 inches so you do have to watch line losses, etc. There is, on the SS site, a video that covers designing the piping system for a typical system and they delve into the line size, the trade offs, the need for a solid 4000 FPM for good chip collection.  Theoretically that works out to a 4" diameter hose but that is pushing it!  A pair of 2-1/2" hoses is more reasonable and that is, indeed, what the DC-3300 is normally setup with.

Thanks for the suggestion about the Brute can.

Bob Groh, Blue Springs, Missouri