The exact purpose of the solution i can not tell. But this part of a bigger solution, where the amount of positions is predefined/limited with a high repeatability demand. To meet this demand a kinematic solution is preferable instead of an active controller.
A tapered shotpin needs a sleeve...
I have the following case:
A camroller that is preloaded by leafspring into a V groove on a disc of circa 150 mm diameter that can rotate. The precision is key in this case and there is chosen for a camroller instead of ball because of the possibility to use rolling friction instead of sliding...