Thought I would move out of the Solar System model thread to allow for those interested to share experiences as this build progresses.
Leo76 (with me helping), aims to have this:-
http://www.build-model-orbiter.com/index-aus.html
http://www.youtube.com/watch?v=rQcxoEv8Ft0
After six issues, Leo76 has a rotating Earth (see attached) and seems thrilled with it!
We can see an immediate problem being the correct alignment of the angled cog that turns the earth daily on its axis. If the big cog is too high, it jambs. If too low, it loses contact.
We can get it right (and tighten the grub screw that came with Issue 6 at the right point) BUT one has to watch for the "decorative top nut" coming loose and allowing the small cog that drives off the angled cog, to drop and jamb. Later, we'll add a little glue to the top nut and set it to the correct position and leave to dry. A task for somewhere towards the end of the build, I expect.