Posted by David Sherman on Saturday, August 02, 2003 at 4:27PM :
In Reply to: Broken Stud - help needed posted by Mark in NW OR on Saturday, August 02, 2003 at 3:48PM :
Drilling out hardened studs is never easy. If the drill doesn't stay entirely in the stud, it will quickly wander off into the softer cast iron. If the stud protrudes, the best is to weld a bar onto it. You might be able to carefully stick-weld a piece welding rod onto it down in the hole. If it broke due to being rusted in place, you will have to somehow loosen up the remnant before it'll come out. Kroil or melted paraffin seem to be the favorites. If you determine to drill out it, try using a top-quality left-handed drill bit of the largest size that will stay entirely within the stud. With luck and penetrating oil it might come right out. If not, a gentle attempt with an easy-out might do the job but be sure not to break the easy-out off in the hole or you'll have even more trouble. If all else fails and there's enough iron in the vicinity, you might have to tap it out larger and use a larger screw or put in a helicoil.