Mini-Cyclone Separator
My mini-cyclone dust separator - two trashcans, two HVAC fittings,
some 8" snap-lock pipe (to reduce velocity of exit air), and even
a plastic "is it full yet" window in the bottom can. It is all assembled with
quick-setting epoxy and sheet metal screws, and sealed with "gutter weld" caulk.
Everything but the cans came from Home Depot. The cans were cheaper at Menards.
All cutting was done with a metal-cutting blade in my Milwaukee jig saw, and LOTS of
hearing and eye protection.
It works well. The bottom can gets quite full before any dust starts moving into
the lower bag of the DC. With my Grizzly G1029 DC with
canister filter,
I see absolutely no dust or chips in the clear bottom bag. It is probably not
as good as a real cyclone - I realize it doesn't have the height or the taper
at the bottom that a real cyclone does - but it is sure better than a flat lid
with two 6" holes in it.
It is also easy to empty the bottom can. The last picture below shows it as installed
near the DC. I can lift the top can off the bottom one, and rest the top assembly (with
hoses still attached) on the lip of the DC's shelf. I can then slide the bottom can out,
for emptying.
The output - a 8" to 6" fitting with 8" snap-lock pipe. This pipe, and the vane
shown below, keeps the intake air spiralling around the outside of the upper can,
which slows it down and lets
the sawdust drop out and fall into the lower can.
Having the output pipe extend down 14" or so
lets this process happen before the air is sucked out the exit pipe.
Having the output pipe be 8" in diameter means the exit air moves slower than the
intake air, also letting more dust drop out.
The length and diameter of this output pipe were calculated
based on guidelines from various cyclone design pages,
determined primarily by the diameter and height of the "cyclone".
The intake vent, a HVAC register fitting, 6" round to 10x6" rectangle. Cutting this opening
in the garbage can was very time consuming, gradually making the opening bigger until it fit.
I folded out a part of the metal flap created by this cutting and used it to reinforce the
attachment of the fitting (where all the sheet metal screws stick out in the picture).
The intake vane which ramps down, forcing intake air to spiral downwards.
This minimizes turbulence caused when intake air swirls around one
revolution and hits the intake HVAC fitting and newer incoming
air - the swirling intake air is hopefully below the intake
fitting by the time it moves one revolution around the can.
I had to ensure the 8" output pipe did not hit this vane, or the intake fitting.
The output pipe comes right up to the inner edge of this vane.
The brown area on the inside of the can below the vane is part of a plastic floor mat,
to protect the can where it gets blasted by the incoming
sawdust (I got that idea from someone on the web who had either wear
or rust due to this blasting). The duct tape was to hold things while the epoxy and
caulk dried - it is not used to hold anything together :-)
Here it is, installed.
It's hidden a bit behind the hose spool for my air compressor.
The clear bottom bag on the DC stays empty.
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