If you have ever worked on vintage or even brand new machinery eventually you will break a bolt or a stud.  Below are various methods I’ve used to remove them.

Welding a nut on a broken stud

	While removing an intake manifold from a 60 year old Power Wagon 3 of the 4 bolts broke, luckily the other 2 still had exposed threads and were no problem to remove by threading on a nut and welding the center. Unfortunately the last one broke flush, first step is to grind off enough metal to expose bare steel to weld on.
	Next place a washer that has a hole the same or slightly smaller diameter than the broken stud.
	Using a welder weld the washer to the top of the broken stud.  Be sure to grind off the slag before the next step.
	Place a nut that is as large as possible on top of the welded washer.
	After welding the nut is glowing red hot, the heat helps loosen the broken stud.
	After about a minute the stud has cooled enough to use a wrench to extract the stud.  The nut isn’t perfectly centered but still the stud came out.
	The finished product is an undamaged bolt hole that doesn’t have to be drilled and tapped.