[nsnick]

The SR-71 leaked fuel before takeoff because it needed separation distance between parts to allow for expansion. It had nothing to do with the difficulty machining titanium.

From your source: "Fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was achieved as the airframe heated up and expanded several inches.[30] Because of this, and the lack of a fuel-sealing system that could handle the airframe's expansion at extreme temperatures, the aircraft leaked JP-7 fuel on the ground prior to takeoff."