[danshaffer]

I believe Art is well aware of that, but is calling out the fact that if you grab the ball at it's center point (equivalent to the Earth's equator line) then you run the risk of going outside the virtual cylinder with your robot.

But as you can see in my quickie CAD, you should still have plenty of room to grab the equator.

That's a 28"x38" robot on the left, a 40" ball on the right and all in an 80" circle/cylinder.