I was directed to this video by a link someone supplied in a Mini Lathe forum I joined a few years ago.
As long as I have been turning wrenches, I had never heard of this technique.. While I have to admit it’s pretty brilliant, it’s also a lot of hard work and it’s not exactly cheap either.
Still beats the hell out of the alternatives.
I especially liked the drill guide idea, that could be handy all by its self.
It took this guy a long time but he did eventually drill an intentionally broken off tap, in a broken off bolt, clear out of a hole in an aluminum oil pan without damaging the original hole.