All I am really asking is "why" does the grub-screw not hold the eccentric in place while the initial running and adjustment is taking place? - If because there is is too much torque required, or the oscillating torque is fatiguing the interface between grub screw and shaft, then no amount of fettling will satisfactorily acquire enough torque to overcome the failure of the contact point under stress. BUT changing to a large surface contact in whatever form should provide more torque to be transmitted.
Maybe it is Mass, Acceleration, or simply Friction that is generating torque high enough to cause the slippage/contact point failure... in which case reduce what is possible (Friction?) or increase the surface contact area between screw and shaft - with something that will conform to the shaft surface?
So while many have used grub screws and had no problem, and many have done other things to increase the torque capability of the joint, Davidyat has a problem, and I am proposing there is a root cause that simple grub screws are not resolving. So as adding a "fixed point" on the shaft is not what he needs during the initial tuning phase, that is the final fix after the tuning that he is struggling with.
K2
Maybe it is Mass, Acceleration, or simply Friction that is generating torque high enough to cause the slippage/contact point failure... in which case reduce what is possible (Friction?) or increase the surface contact area between screw and shaft - with something that will conform to the shaft surface?
So while many have used grub screws and had no problem, and many have done other things to increase the torque capability of the joint, Davidyat has a problem, and I am proposing there is a root cause that simple grub screws are not resolving. So as adding a "fixed point" on the shaft is not what he needs during the initial tuning phase, that is the final fix after the tuning that he is struggling with.
K2