Using the boring bar! It's worth noting that Titanium CAN catch fire in a lathe!!
It's like magnesium. Thus, it's essential to keep things cool with the coolant and to clear the titanium hair.
My big time-waster was not finding a way to shorten the stock before starting my adventure. Everytime I did something, runout would build into the spin. (from 0.005" to a millimeter it seems) This would lead to an inconsistent loading on the tool, and perhaps the impacts of the tool leaving and hitting the titanium were hardening it and causing the chatter to build.
I ended up figuring out a strategy though! If I advanced the tool position (radius of the ring) while the boring bar is inside the ring cavity
prior to coring everything out, then I can advance to the next depth without introducing more chatter . It seems the act of going into the material with the next depth already set causes the runout to multiply.
Thus, I could proceed. 0.002" at a time!!!