[GBC]Compact cycloidal drive

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... whis is, of course, a personal remake of a famous design from Akiyuki !

(because I admired how he turned/staged industrial speed reducers into ball transportation mechanisms)

Another motivation was that some famous GBC designers (Josh DaVid, Sawyer) re-create well-known designs in a smaller form factor.

And of course, the "self-challenge".


So here is my currently final work (despite not yet well-polished regarding input and output's aesthetics) :


And a quick test in a (very short and low-resolution) video : (my usual camera failed recently ==> I used an old working one).


As introduced before, I haven't changed the core mechanism, which relies on the two following main tricks :

  • using 180-53° liftarms for building the heptagonal structure of the "rotor" (only approximately 2° of mechanical stress per side)
  • central pivot achieved by a pseudo gear bearing (pivot = sun gear ; rotor = planet carrier ; no ring gear) because no 7-beam hub does exist in LEGO and less than 7 beams is impossible because 7 is a prime number (whereas Akiyuki's rotor has 9 sides ==> 3 --double-- beams on a 6-hole pulley)


The only changes I made (since the above older pictures) were :

  • on the stator, new support structures for the big "teeth" and a brick-based rear wall (for preventing the rotor from wobbling and jamming)
  • the ball catch mechanism : instead of the previous 3-finger layout (with one moving finger), I switched to Akiyuki's 2-(hollow)finger solution, using old crank parts and the material's flexibility :
    • it takes less room, making the ball catching easier
    • the ball can be pushed in/out in perfectly opposite directions, making it possible to load it at the very bottom and to unload it at the very top

Then I managed to build the output ramp and input mechanism (input bin with basic steering + 1-by-1 ball distribution) and to adjust them, after several trial-and-error steps too.

(I initially attached all the elements on a baseplate in order to quickly adjust them with respect to each other, before linking them together in the form of a hollow but stiff chassis).

The mechanical inputs are a crank (behind the stator) and a motor input (behind the input bin).


Edited by Thierry-GearsManiac
minor corrections

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