Titanium untreated, is really soft and very easy to ding. From the few parts I've machined, it turns real well and gives a good finish straight from the tool. However.... Cutting tools must be kept sharp and lots of cutting fluid should be used. As soon as the tool starts to rub, the surface will work harden and become a bitch to machine. Also helps if you can run at high speed and take heavy cuts.
Originally Posted by Curt
The alternative is Stainless Steel - Not as heavy a plain steel, not as bad as titanium for work hardening, and readily available.
Oh, did I say titanium burns very easily - Flood the work with coolant, keep the work area free from swarf, and don't let it get red hot.