Hi Raulruegas
Thank you for that.
Whatever knowledge I have has taken more than 70 years to acquire.
There is too much dogmatism here, as others have observed, but this is entirely understandable. What we want to avoid is slagging one another off or alleging lack of knowledge in someone we have never met. We can share knowledge and, indeed, opinions without that.
Sorry atmasphere, you are incorrect. At least from a technical standpoint. If it is not over-tightened then it is free to move. If it is free to move then there must be an interference gap, however small, between the moving parts. I don't think the hardness of the materials used has any bearing (ho ho) on the question. As long as the surfaces are accurate and finely finished, their hardness will only affect the service life of the piece.