1. #1
    Hey there,

    I think i bumped into an interesting dust separator while browsing the tube , that i would like to share with you.

    I have this older variant mounted on top of 200l steel barrel.

    Click image for larger version. 

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    Works pretty well but as recently i make a lot of dust per day, 93-97% efficiency translates as 5-6 times i have to clean my shop vacuum cleaner until i fill the 200l barrel in which i could pack 100kg and more of dust. cause 5% of 100kg is 5kg of fine dust that escapes the dust trap.

    Most videos show how it captures 1kg and the result is great. They should really do a test after 1 day 8h nonstop work.



    So i started to look and see if there is sth new on the horizon last years. It seems there is. 2 models more:

    Click image for larger version. 

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    They seem smoother curved and maybe a bit more efficient.




    But then i found maybe even a better idea.

    Here is the video:




    Here are the photos of his prototype:

    Click image for larger version. 

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    From the video even at first glance it looks better. I am quite into making myself one these days. It says centripetal forces, not centrifugal. I still dont get how that works though? The air is sucked like a fountain in the middle and the outer side of the waterfall pushes the dust to the walls? or sth like that.

    Here is the original description from You tube:

    " The fastest, most effective, and efficient dust collector ever made (sans a filter). The video shows a prototype device actually removing dandelion florets and down-feathers from a 60 mph air-stream to a wet/dry vacuum. This Patented device uses centripetal forces to rapidly (less than .02 second) remove debris from airflow between a debris source such as a woodshop power tool and a vacuum source such as a shop-vac. Prior devices rely on gravity to remove the debris from a cyclonic airflow, which can be very slow. Consequently, those devices are not very effective (remember, stuff goes up in a tornado, not down).

    This device comprises a first chamber that is situated above and adjoins a second chamber. The first chamber is dome-shaped and has an upper centrally mounted output port that connects via a hose to a vacuum. The first chamber also has a downward and outward sloping sidewall such that debris-borne airflow entering through a tangential input port is centrifugally forced to the inner surface of the sloping sidewall. The debris is then centripetally forced downward into the second chamber through a 1-inch, 360-degree, peripheral opening between the lower edge of the sidewall and a disk-shaped barrier that's concentrically suspended by 3 equally spaced brackets. It should be noted the lower edge of the first chamber is configured to sealably fit the upper edge of the second chamber, which may simply be a bucket or a trash can. The first chamber functions to separate and efficiently remove the debris from the airflow while the second chamber functions to collect the debris. The first chamber is low-profile so it is less prone to tip over than previous dust collectors.

    With an effective Dust Collector (Debris Separator) such as this, the vacuum's filter remains unclogged for longer periods and the vacuum itself runs efficiently longer. This saves the user time, money and frustration and also saves our landfills of superfluous waste (the shop-vac filters). "


    So what do you think? It looks much lower height / the lid/ and much easier to make than DIY cyclone. I have to test this one and sooner the better. Anyone got a barbecue that needs replacing? :-)
    Last edited by Boyan Silyavski; 25-09-2016 at 06:47 AM.
    project 1 , 2, Dust Shoe ...

  2. #2
    Greeny's Avatar
    Lives in North Yorkshire, United Kingdom. Last Activity: 22 Hours Ago Has been a member for 8-9 years. Has a total post count of 102. Received thanks 12 times, giving thanks to others 7 times.
    Great find, that looks really interesting!
    There is some good info in the patent images at http://www.google.co.uk/patents/US8337580
    (didn't want to post 'em as unsure of copyright, but they are available to download from above link)
    Although it's patented for commercial applications, from the comments on the video, the designer seems to encourage homemade versions.

    I'm pretty sure it works in the same broad manner as other cyclonic dust extractors, but with the addition of the dome lid & separating plate which appears to increase it's dust collecting efficiency.
    Heres how i think it works. (Could be way wrong )
    The shop vac creates a negative pressure in the dust collect collector this 'sucks' dust in throught the inlet, the rapidly moving dust then wants to travel in a straight line but cannot because of the circular shape of the lid.
    it is forced to move in a circular motion around the lid. from the point of view of the dust it has a massive centrifugal force acting outwards pressing it against the inner surface of the lid. because the lid is dome shaped this also forces the dust downwards to drop
    through the gap around the edge of the plate, into the bin. (Gravity gives a very small help as well, but it's tiny for very fine dust). presumably the plate that separates the lid from the lower bin helps to stop dust already in the lower bin from getting back up in to the upper chamber and into the shop vac.

    Centrifugal force is the outward, so called 'fictitious force', that is 'felt' by rotating objects, in this case the dust.
    However if you look at it from the bins point of view, it is exerting an inward, centripetal force, forcing the dust to travel in a circle around the lid.
    So either Centrifugal or Centripital force can be used to explain it. They are very different, but also very closely linked. (They both arise from objects moving in a curved path.)


    Been a long time (years!) since my last post. Arrived and asked a lot of questions then disappeared!
    Just finishing off my Shed/Workshop & hopefully will be posting a real build soon, and also very keen to try and have a go at making one of these too.

    Cheers
    Last edited by Greeny; 25-09-2016 at 10:41 AM.

  3. #3
    Quote Originally Posted by Boyan Silyavski View Post
    It says centripetal forces, not centrifugal. I still dont get how that works though?
    Centrifugal is an imaginary force used to explain behaviour, Centripetal is a real force, he may still not get the Physics though as Centrifugal and Centripetal are equal and opposite forces despite one being imaginary ;-)
    Last edited by magicniner; 25-09-2016 at 11:25 AM.
    If you will not be swayed by logic or experience simply pick the idea you
    like best, but ask yourself why you sought advice in the first place and,
    for a simple life, perhaps consider not doing so in future

  4. #4
    Ok, after reading the patent i see now exactly how it functions. The idea is great. The separating plate is the detail that will stop the miniature dust from entering the outlet. I cant wait to make myself one lid.
    project 1 , 2, Dust Shoe ...

  5. #5
    This isn't new. It's a Thein Baffle, been around for ages I've built a couple. And they are included in many commercial designs.

    It works as described above. negative pressure draws air and debris into the drum tangential to the side causing the flow to swirl around the circular chamber where the particles with higher mass fall to the outside through the slot. When you look in the bin after it's been used the large chips are all around the outside of the bin and the finer stuff near the middle.

    As to the original problem, the issue I suspect will be that the cyclonic separator you have is simply not man enough for the job. The cyclone works on a similar principle of imparting angular momentum to the dust and the conic portion helps maintain the angular velocity of the vortex as the dust falls. It is VERY efficient. However the problem is that if the saturation of dust and chips in the incoming air is too high then there isn't enough energy in the vortex to throw it all outwards and you end up with dust being sucked through the centre because it can't be thrown against the side. You simply have too much dust going into too small a conic section.

    You need to get the balance between pressure differential, hose diameters, rate of flow, and conic cros section in the sweet spot. Yours I think is simply way too small for the volume of dust.

    A cyclonic separator is a much more efficient design than a Thein baffle and should be upwards of 99%. The thein baffle is just sooooooo much easier to make as it's basically a 2d plate not a smooth 3D conic section. Check you tube lots of wood workers make both. Traffic cones are useful for this but pretty small!

    There's a whole science on chip and dust extraction, where chips and dust are not the same thing. One requires high volume low pressure extraction (HVLP) the other low volume high pressure (LVHP). Most shop vaccs are LVHP.

    Axminster tools used to have a very good explanation of extraction differences and they sell extractors with both thein baffles and cyclone separators.

    Hope that helps.

  6. #6
    I see. I am also playing around with dust shoes, DIY separators, etc. I went to the conclusion that for my CNc the best is 2-3 stage shop vac LVHP and a hose around 40-50mm, no bigger than 60mm. I have very serious 2.500w 2 stage vacuum cleaner using 42mm hose that sucks very well.

    These Chinese separators suffer from design flaws. One thing is that the dust rotates inside but will not go down until i stop the vac. Previously i had Thein Baffle type from a bucket like thing, it was more efficient. Though at that time i did not know to separated the area with a plate so i does not suck back the fine dust floating around.
    project 1 , 2, Dust Shoe ...

  7. #7
    fifa's Avatar
    Lives in bristol, United Kingdom. Last Activity: 6 Days Ago Has been a member for 0-1 years. Has a total post count of 22.
    Remove large debris (saw dust) from air flow is not an issue. Dust thinner than 20 microns is harmful for human lungs. We are not able to filter it.


    I am using cyclone and reusable bag from HEPA filter in the intake of workshop dust collector Bag has a zip on one side for empty. Works good, however claims like 99.9% do not say a lot. Even "clean" room air has some dust in - would this device clean it?

    The best way is exhaust the air outside of the workshop. This works well during the summer, during the winter we are loosing to much energy. Simple cross recuperater helps to harvest it back.

    I am hobbyist. However I am surprised how much dust come through filter anyway. It colour the snow.

    regards
    Last edited by fifa; 19-02-2017 at 08:20 PM.

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