Non-Circular ring gear?

[Scott Beale]

I'm on such a learning curve here, I'm in need of a pattern for a 3rd order ring gear with in inside gear roughly the shape of an egg. The axis of the pinion gear needs to travel in a perfect circle. I've been researching this all weekend and could really use some help. Thanks in advance.

[ArtF]

Hi:

  By definition I dont think that exists in pure ellipticals.  (If Im understanding.). Do you mean
as the gear rotates inside the triangle you want its axis to draw a perfect circle? That sounds
impossible....though Ill give it some thought...

Art


 

[Scott Beale]

I'm sure I didn't explain that well. here is a very rough sketch of what I'm looking for. The heavy circle would be the path of the pinion axis (dia=100mm).

[ArtF]

Ahh, my appologies then, it is not only possible but inevitable.
Any 1st order running  in a third order ring always forms a circles on its pinion axis.

Consider the attached example, both items can rotate in mesh without their centers
moving on the screen at all, this means that the pinion center is forming a circle
around the center of the Wheel....

If Im now understanding it right..

Art

[ArtF]

Ohhh.... I forgot you want a 100mm circle in the middle.. so.....

A mod 3 pair will have a center distance of 31.7095.. thus
you need a

3 x 50 / 31.7095 = Mod 4.73044 to get a 100 mm circle in the axis
pivot of a 3rd order ring with a 1st order pinion..

( Use GT, not GM, the ellipticals are soo much better.. :)  )

Art

[Scott Beale]

Art, thank you! That's exactly what I was looking for. I was just using the demo version, I definitely want this for my "Tool box", so I just ordered it. Thanks again.

[ArtF]

:) , Glad it helped.

Art