In the link above you will find .blend that has one bone and one sphere copyrotted to it with influence of .75 or something (less than 1 anyway). When you open the file. Roll the frames forward and keep your eye on the ball, you will notice odd “flip” in local axis coordinates and the ball flips. How do i get it NOT TO DO THAT?
The mechanism shown in the blend is part of larger “machine”, which purpose i think is best left untold as i cant really explain it… And there is “Influence” involved so straightforward parrenting wont work.