> Think about that for a moment...why should the path that the vertically-oriented motors take affect the horizontal rotation of the arm? They effectively weig

> Think about that for a moment...why should the path that the vertically-oriented motors take affect the horizontal rotation of the arm? They effectively weigh less when they're far apart. If you look from above (like their video), the curved track means that projected down to the plane it's rotating in they're closer to the axis.