Thanks very much for the responses, didn't expect anything this quick! I've checked them both out and it seems so simple (always is when someone shows you the answer).
Both examples are very similar so I'll do a bit more research into them both and have a 'fiddle' to see what I can come up with. One thing I did notice on the cube you posted Carl, was that it looks a bit skewed on the slower rotations which I'm sure is something to do with the perspective and the way we are 'looking' at the cube.