[varjag]

Machining grade 5 titanium alloy (the most common one) is not especially challenging; it's easier than 316. Saying this as I did machine it personally on a manual lathe.

From the initial endmill size they use and the generous machine sizes (which can be extrapolated from chuck/table size) we can easily tell rigidity/chatter wasn't a particular challenge here. And the finishing passes are so delicate they don't even bother with coolant for that.

Yes the code to run all this would be a monumental undertaking in the 70s but it is done once and can be still entirely cost efficient as far as mass production is concerned. The thing new machines have is the running speed (for same precision work). These did improve a lot and make certain classes of products economically viable.