The Thien Separator Inside A Craftsman Wet Dry Vac

[Kelly Bellis]

r2 - I found this nugget from Phil.

Leaving some room between the elbow and the baffle will prevent dust from packing in between the two.  1/2" to 1" is sufficient, depending on the type of materials you work with (softer pine, with stringy shavings, needs a little more room so I'd go 1" if you work with a lot of it).

[retired2]

And if you are really interested in improving the performance of that separator, cut a slice off that inlet elbow and get on with it!

Nothing is being caught under the pipe r2, so why cut the pipe?

Alternatively, would increasing the height between the pipe bottom and the lower disc be satisfactory, say by 0.5"?

Raise the pipe or slice it off, either works.  And you do it not just to eliminate clogs, but to help smooth out the air stream. 

[Kelly Bellis]

... the 120-degree portion starts back at the bend of the elbow.  So the particle travels along all but approx. 2" of the 120-degree portion.  I found this design worked best to reduce turbulence at this critical point.

D'oh! I missed this earlier. I'll definitely include this design criteria for my next go at it! Thanks Phil!!

Now that I start to try and draw this, I'm less certain what you meant here Phil. Is the drawing below in agreement with what you meant?

[Kelly Bellis]

@Phil - Alternatively, and what I had to begin with was the drop slot terminus coincident with the centerline of the vertical axis of the elbow, as seen here:

[Kelly Bellis]

Funny Story
Test 5's new lower baffle was laid out, drilled, and on the router jig when I heard back from Phil with his answer to go with A in regards to the drop slot terminus question posted above. Because of the drilled hole's location for the router bit, I couldn't quite get it to A's position, but got it as close as I could  ::)

[Kelly Bellis]

Experiment #1, Test Series all have a straight pipe outlet. Experiment #2, still only in the planning stages, will feature the bell mouth style outlet. The geometry for the elliptical bell mouth pipe, plus the design criteria of its vertical position, plus retired2's comment of increasing the height between the bottom of the inlet pipe and the lower baffle, then all contributed to Experiment #1, Test 5. Also seen in Test 5 besides an increased gap between upper and lower baffles: no support brackets beneath the lower baffle; three spacers separating upper and lower baffles instead of 6; and lastly, lower profile wooden knobs with embedded nuts. The knobs are a critical bit of kit as the upper baffle sits quite snugly in the plastic barrel when properly seated along its scribed line.

[Kelly Bellis]

Experiment #1, Test 5
After vacuuming up the dust from using the router on the hardboard and other operations, I went back to the box under the table saw still quite full of saw dust; maybe five minutes in total of vacuuming. The results weren't as pretty as was hoped and tend to suggest that the lower baffle was not being held stationary with its 120? edge tight against the barrel. This may possibly be attributed to the amount of flex observed in the assembled structure in spite of efforts which included epoxying the threaded rods to the lower baffle and snugly tightening the nuts on the three spacers.

[retired2]

I did not take the time to look at your dimensional information, but don?t be surprised if the bellmouth results in more by-pass.  I have often cautioned about the use of bellmouths in small diameter separators.  The flange brings the exhaust air stream much closer to the circulating waste stream and picks up waste before it has separated out.  This advice has always been given to top hat builders, but I think it is still valid for your application as well.

[Kelly Bellis]

Thanks r2. If I get that far with these tests, I'll not be surprised, but so far, all of my tests have indicated that getting the same kind of performance that users of the trash can lid type Thien Separator get (with a straight pipe) is difficult, at best.

One element that's potentially exacerbating my efforts of getting the Thien Separator inside the Craftsman shop vac to perform well is static electricity. It isn't a large quantity, but it has been consistently present in all five tests so far.

Home Depot was out of the regular variety of hardboard, but had in stock what is known as Eucatile and is made in Brazil. I bought a 4' x 8' sheet and that's the type of hardboard that I've been using. "Eucatile is a scored surface melamine based and infra-red cured top coated hardboard" according to the manufacturer, Eucatex.

After the vigorous scrubbing over the melamine surface, then there is the plastic barrel's walls being rubbed against at high velocity. I couldn't find an HDPE stamp or any other indicator on the barrel, but am guessing that it some form of high density polyethylene.

I do not know how much of an effect any of this has, but it is none the less observable and worth mentioning.

[Kelly Bellis]

Here's the label that's on the back of the sheet:

[retired2]

I can?t help you with the static cling.  I get a little fine dust that clings to the plexiglass walls of my separator, but in operation the static has no effect.  If anything, the circulating waste stream keeps the walls from accumulating anything but the finest dust.

[Kelly Bellis]

For now, I've called a truce with the sawdust having just now reassembled the Sear Craftsman Wet Dry Vac Model No. 113.1768081 back to its original configuration. I'm not admitting defeat, just that the saw dust has been smarter than me in this little dust up that's been going on for the past two weeks.

I've ordered the Dewalt DW735X planer with its much celebrated chip ejector and I plan to build a Thien Separator for it, though I'm thinking maybe of using sheet metal for the inside walls instead of clear polycarbonate or acrylic.

[retired2]

Don?t underestimate the value of clear walls, it is much more than a novelty, unless of course you put the whole thing in a soundproofed enclosure..

[Kelly Bellis]

There is another reason to avoid plastic pails, though. And that is to avoid static problems. I'm not concerned with the chance of explosion, but rather have noticed that static charged plastic can interfere with the operation of the cyclone.

Amen.

[1Architect]

Without any dimensions, I can't really tell, but it appears that you have built down into the collection area of the bucket (bottom) so deeply with the separator, the vortex doesn't have sufficient room to slow and drop the debris below the baffle.  My guess is the airstream is moving the waste through the slot and then picking it up again on the way to the filter - scrubbing.  It's the reason most waste containers with separators sitting on them, have to be emptied about 1/2 to 3/4 full.