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Epicyclic Trammel

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Planetary gears meets the Trammel of Archimedes

 

 

might amuse someone 😀

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    Version 2 is more planetary ie the planets move -

     

     

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    Quite fascinating.

    Are there any real world objects that use an epicyclic trammel?

     

    ...and if If "Epicyclic trammel" are not a rock band, someone really ought to form it : )

     

     

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    Archimedes made a 2 slot trammel that drew ellipses.

     

    https://en.wikipedia.org/wiki/Trammel_of_Archimedes

     

    I made one in C4D a while ago that had 3 slots

     

     

    Recently I saw this device on YouTube, and thought I'd try it with 2 spinners

     

    screenshot.png.a4a0af29327fc1104f72fe810dee08d1.png

     

    I imagined I'd need some trig to make it work, but it seems the small object just has to rotate 2X the speed of the large one. Not sure why... 

     

    I got a bit carried away, adding planetary gears 😀

     

    I think epicyclic gears are used in electric screwdrivers, and Sturmey-Archer 3 speed bike hub gears.

     

    Epicyclic gear math can be a bit difficult, but you're welcome to look at my methods

     

    trammel 9.c4d

     

    here's a regular epi system that has sliders for speed

     

    epi.c4d

     

     

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    Thanks Jed - I'm always interested to see files like these. Facinating stuff.
    You might enjoy this youtube channel that I stumbled across today - a retired Vietnamese engineer making animated video of various mechanical setups - over 3,000 of them I believe!

     

    https://www.youtube.com/user/thang010146

     

     

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    @MikeA thanks for the link - there's a ton of ideas there. Thang knows his stuff.

     

    After I made the model in post 1, it bugged me that although it worked, I didn't really understand why the red spinning part had to rotate at 2X the speed of the larger part, and even why the cylinders stayed in sync in the slots. I have managed to solve it with a bit of simple geometry if you're interested -

     

     

    turns out the size of the red part doesn't matter -

     

    spinner-test-small.gif.524acf3f588c2b53c6789595f2f45b11.gif

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    I very much enjoyed that Jed - and you would have made a great maths teacher!

    If you concentrate on that red spinner above it's quite hard to convince yourself it's not moving left or right : )

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    @MikeA - I had a go at one of thang010146's YouTube  designs

     

     

    I'm always impressed at how well C4D can handle difficult dynamics situations. I don't think I'd be able to animate those cogs with math.

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