I got the Bucket Wheel Excavator in September last year, and after building it and modifying it (with Mindstorms), I dismantled it to use the pieces in my other Mindstorms creations. I'm particularly interested in the large yellow planetary gears/rings that come with the set, I hope to use them to create some sort of tank with a rotating turret. However, I'm not too sure about the geometry of the pin-holes in the rings, I don't really know where it is safe to attach a pin in a certain hole. If anyone knows of the correct geometry of the rings, it would be very helpful!