Dust Extractor

A 3D printed cyclonic dust extraction attachment for a domestic vacuum cleaner.

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A printed dust extractor attachment for an upright vacuum cleaner. Being sick of killing my vacuum cleaners because of the, literally, stupid dust extraction methods they use I decided to design and build my own.

Restricted to the printers build platform size I went about researching how cyclonic dust extractors worked. Realizing that there is essentially only one method to extract particulates from air without a mechanical filter it was a matter of optimising this is a system. Seeing how the branded cyclonic vacuum cleaners work I thought that they weren't really the best solution for the printed construction method and maybe not a good as they suggest.

Cyclonic dust extraction methods aren't new and are common in industrial settings. The principle is that a vortex is created with rotating air. In the middle of that rotation is low pressure and the more energy that the vortex has the greater the difference in pressure, eg lower. So using the low pressure region and the centrifugal of the rotation a complementary mechanism exists for the particulate extraction process. Air at the centre of the rotation has the lowest pressure and only the most buoyant substance can sit there which is only the cleanest of air. Extracting this air with a vacuum pump is essentially do the most natural thing for a cleaning process.

Typically industrial dust extractors use a single vortex that removes the large particulates that cause dust. The commercial domestic vacuums require more finer particulate to be removed and use very small vortices to do this. Without going to this extreme this project created a 5 vortex system with and external bent vortex that induces the rotational air structure.

This image shows the inner 5 vortex generator that the inlet air structure rotates about. Large particulates are removed here as the air accelerates over the curved surface and into the inner 5 vortex generator. The slow moving 'high' pressure air that contains the particulates from the small vortices exits below the accelerated feed air and should mix with the large material and fall to the bottom.

  • The build.

    Nelson Phillips04/25/2017 at 08:00 0 comments

    Without going into to many details about how I came to the dimensions because to logic was crude and was mostly governed by the size of the vac and flex hose available.

    This give a rough guide as to size of the body, the hose was limited as the common flex vacuum hose was just a bit to big. Searching I came across so 22mm outdoor water hose, not ideal but it would work in the constraints of the vacuums camber. The image below shows the original idea of a bracket interfacing with the chamber inlet, but it also shows the space constraint.

    The hose needs to sit there then turn and exit just where that dark circle is drawn because the filter that i was always planning to keep took the remaining volume. However, it turned out that the hose would fit inside the inlet perfectly creating a stable seat.

    No going back from here the holes where drilled and filled, and the hose inserted.

    Going back a few steps because I printed the extractor first, but these images illustrated some early design decisions as to how the space inside the chamber was a major influence. For example on of the original idea was to have the extractor contained within the chamber. The tightness of space and lack of ability to model parts exactly to the shape and dimensions of the chamber ruled this out.

    The filter and the chamber that it came from.

    Design and CAD

    Knowing that the dust extractor is a common and relative old technology the design started from gaining knowledge of how this technology actually worked. Standard dimensions were easy to find and simulations consolidated some thinking about the lower portion of the cyclone.

    The principles set the cyclone throwing the dust to the sides and it then falls below the cyclone to the chambers floor. But, having a single cyclone would require a larger chamber and from principles it would not have a high velocity air speed. So splitting the flow into originally 4 then 5 cyclones would substantially increase the angular velocity.

    Printing the flow generator also provided design constraints but also opportunities with an organic structure separating the incoming air and the high velocity cyclones. From here however it is not clear if this provides a solution but this is what I printed. So fingers crossed.

    bottom half

    top half

    and together

    All the parts printed.

    The upper and lower cyclone generator solvent welded together.

    A threaded attachment was printed separately and stuck to the chambers inlet with the help of silicone.

    similarly the outlet

    Inlet to the vacuums chamber.

    And the final result with brackets printed, solvent welded, drilled and screwed.

    It does work.......

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