proculap montana: how high is that plastic tube? 14"?
freshpootube: That 90 degree bend for the inlet seems to work great. Lots of other
versions, people go to great lengths to create a curved angled inlet on the
outside of the cylinder. This shows it may not be necessary?
John Delaney: Nice video! That pretty much clears it up for me! LOL! Seriously, I think
this is the way to go.
johnisnot: Note that you aren't seeing *air* going down into the slot, just debris...
The bulk flow of the air is all above the plate, with mixing at the slot
due to turbulence.
johnisnot: Google "thien separator". The incomplete slot around the outside is part of
the design. I haven't tested it myself, but the idea is that the plate
decouples the airflow above and below, preventing the collected debris from
being picked up again.
Gid joiner: Hi, finally found a container suitable to make one of these, experimenting
a bit for now but cobbled together a quick version of yours this Sunday
afternoon & i was very surprised at how good it worked, Thanks seeing your
see-through version has inspired me to build one in the first place & now
I'll take it further, :-) ps I've put a crappy vid on my channel to show
johnisnot: I'm *very* sure you don't want the outlet below the plate. The idea is that
the area down below has low air velocity, so that lighter particles stay
put. This is just a simple cyclone separator, except instead of a long cone
to separate the collection barrel from the moving air, it just has a flat
plate. The physics are pretty well worked out, and the air basically
spirals toward the central outlet like a whirlpool in a bathtub. You can
visualize it when long (eg. handplane) shavings get in.
Nick Bowlby: Does it seem to work better than deeper, conical versions?
rcdc128: I was waiting for a finger to funnel itself through there XD
ghostses: Hello sir, I was managing some of my videos and this one popped up on the
side panel. I too have made one of these and posted a series on building
it. I've looked at your link to the build and see you made a comment on
things you don't like- but all things taken into consideration, this is
such a great and simple build I just had to post- which I rarely do. A side
inlet may help the hassle- but as to what I see on your video- both designs
work equally well. Great work and thanks for sharing, G.
Krešimir Cindrić: I knew how they work, but I've never seen a transparent one. Very
interesting! :D Thanks for sharing!
johnisnot: I don't know. I haven't compared, and the answer depends on your criteria.
For particles as big or larger than fairly fine sawdust, I don't think
there's anything better because I've seen zero of that stuff get through.
For very fine dust, some other cyclone design might be better, but I don't
think any cyclone is good enough to capture the really tiny particles that
are hazardous from a health perspective.
elsoclan: That is so illustrative with the clear plexi! I've been reading a bit of
dust extraction principles, but this lets you really see it in action. Will
be building one of these, maybe for and update into my current
vacuumcleaner powered cyclone- metal bucket-drag-around-version!
johnisnot: I did try installing another baffle, held up on the all-thread, mounted
just below the inlet elbow. I was interested in seeing what was happening
above and below the plate, and thought maybe it would provide even better
isolation between the upper airflow and the collection can. Bottom line is
it worked better without that plate, and I think a little distance is a
good thing - it just makes the unit a little taller.
paralogos: Ok, thanks for explanation.
Gid joiner: Hi do you think this would work ok with thicker material from a
thicknesser,like small shavings, would the slot to the collection area be
big enough? all the demonstrations concentrate on finer dusty particles.
Prob gonna try building one anyway but as you already have a clear one it'd
nice to know Thanks.
johnisnot: Well, a mixture of air molecules and tiny wood bits comes out the end of
that bent pipe on the left at about 2.5 meters / sec. Those particles want
to keep going straight (Newton's 1st) but we get a separation effect
because the mixture hits the curved plastic surface and the air is
deflected more easily than the wood particles.
Gid joiner: Thanks
johnisnot: It's just a flat piece of 1/16" thick polycarbonate, about 9 inches x 40
inches, rolled into a short tube. It's very flexible.
Dave Smith: Thanks for the vid. You've just given me the confidence to build one
myself. I couldnt work out how I was going to do the cone part and now I
find that it's not necessary at all :-)
DistrictWoodworking: Great job, How did you get the plastic from a sheet to be a circle?
jsteifel: Whats the name of the second 2 motor extractor?
johnisnot: It works great with my "lunchbox" style thickness planer. I even vacuum up
handplane shavings with it when I clean the shop. Sometimes a long wispy
shaving will get tangled around one of the threaded rods that holds it
together, but it has no problem separating larger material from the
airflow. Using the planer, I actually filled up the collection barrel, and
half filled the top separator, and still nothing went through.
John F. Bramfeld: I suspect you are right, but it still nags at me that yours and other
visualizations show at least some air doing down into the collector box.
That air has to come a back up. As typically constructed, there is nowhere
to come back up but through the slit in the outside of the plate, which in
turn may disrupt the air going down to some extent. Being pretty sure and
being sure based on actual observation are two different things. Think
about being the first to demonstrate the return path.
John F. Bramfeld: Great job. I am preparing to make a rudimentary add-on to my shopvac and I
am having trouble conceptualizing the part you can't see in this type of
demonstration; the path the air takes back to the outlet. It's not clear to
me, for instance, that the return pipe shouldn't draw from below the Thien
sparator rather than from above. I wonder if you ran smoke through the
system instead of dust you could actually see the route the air takes after
the wood particles have dropped?
Five Minutes On The Water - And other stufff!!!: I was wondering if you had done any experiments with the spacing between
the collector cover and the baffle. I've notice Thein and several others
have the cover and baffle much closer together than your design. If you
have was there any difference in fine particulate efficiency?
Sirus: Thanks for the upload. seems to catch just as good as the cyclone shape
ones. Nobody is going to win on the fine fine dust, so lets all give up and
have a fine filter for that. I was thinking, seeing these are based on
velocity and vacuum and gravity. Gravity seems to work on this fine. what
would happen if you had the vacuum end a bit higher and just behind the
input pointing opposite to the debris end with a slight tilt to aid
gravity. Faster spin perhaps but less center vacuum.
paralogos: I can`t understand the physics.