Paul Bayly wrote:
EDM is (can be) incredibly precise. It can be used like a milling machine for extremely difficult to machine metals, or to leave square corners for die making. They should have no problem blasting away the stud and leaving the rest. Should be able to eat away everything but the threads.James, I'm pretty certain that EDM won't work in this situation. It eats ferrous metal parts out of alloy but I'd say that trying to eat steel out of cast iron will result in damage to the header.