Without getting into custom tooling, I'd probably drill, bore, then use a full radius 90° groover to get most of the sphere and then use a small VNMG to finish the far end where the groover doesn't fit. The VNMG might be able to finish the whole sphere if there is enough offset.
here is my drawing.
Can you recommend what exactly tool holder size and how much angle that i should use for this
I am going to drill a 10mm hole first
I've not run any cnc lathe yet
i will try them on my DIY cnc lathe lol Test my diy lathe - YouTube