Stuck, broken off bolt

I've had pretty good luck just heating the stud up red hot, let it cool down and then try it. Welding a nut on works pretty much the same with the added benefit of having something to grab it with. After it has cooled some (not red anymore) it helps to spray some penetrating oil on the stud, it will get drawn into the threads as it cools. I was recently told to touch some wax to the hot stud and it would work similar to the penetrating oil, I have never tried it though. The trick is to let it cool pretty much to room temperature before turning it. The theory is that you heat the stud up to were the material softens just a bit and it takes the shape of the hole, then as it cools it actually begins to shrink away from the wall of the housing and breaks any rust or scale that has formed and it will generally loosen enough to turn. No absolute guarantee though. I have done this to studs in castings without cracking the casting, I may just be lucky and I've only done it 4 or 5 times and never on a JD B. And that is most of my 2 cents worth.

I'm sure you'll get lots of recommendations, but here's what has worked for me.

If you have access to a welder, you can weld an nut onto the stud. The heat from the welding process will help free the stud. Prior to the welding, I like to heat the whole broad area with a propane torch. Bringing the larger area up even a couple of hundred degrees will help to minimize the chances of cracking the casting.

You could also grind the stud flat on top, get a good mark on it with a quality center punch, and start drilling it out with progressively larger bits. This method will likely take longer, but it's probably less risky, provided you don't run out the side of the stud.

Good luck !

Frank-in-Tallahassee
70D // 855

Using an acytelene torch (burns hotter)heat the screw and about 1" around the hole red hot just short of bright cherry. Cast iron can probably take it. When it is still real hot jam a wad of beeswax into the area around screw. Let it cool off. Using a small pipe wrench CAREFULLY try to back the screw out ONLY until it "pops". If it gives even a little, heat it again to dull cherry and reapply the beeswax. then working the screw back and forth ease that sucker out. Rots o ruck!