Wobbly gear ring needs fixing

I had a wobble problem too with a rectangle with a curve modifier to a bezier circle.

I had an empty in the center of the circle that was the parent of the rectangle and bezier circle. This way I could rotate the empty and the rectangle would spin fine when animated.

This worked fine on a flat global plane or if I tilted the empty on one axis and did a Local rotation of the empty Z axis. However, when I tilted the empty on both the X and Y axis and Locally rotated the Z axis of the empty I got the dreaded “Wobble” in my animations.

I was using the XYZ Euler, Quaternion, and Axis Angle rotations. All gave a wobble. Someone on this StackExchange suggested trying one of the other Eulers. I had a wobble on the local Z axis I was rotating so I tried the ZXY Euler and it eliminated the wobble, no matter what the local X and Y angles were.

So try some of the other Eulers to see if it helps.

I tried the following method with some success. It's tedious and not very precise, but hopefully someone posts a better solution.

In EDIT mode and viewing ring gear along its profile so it appears as a straight line, I slowly rotated it. Whenever I noticed the profile getting 'thicker,' this indicated a 'wobble' where the opposing arcs are not aligned because the circle is slightly skewed along its axis of rotation at that point. I then adjusted the rotation along the perpendicular axis until the profile narrowed or thinned.

These adjustments need to be made in edit mode so they are applied in object mode.