|The components of the experiment: stem with broken bolt, alum powder|
The one kind-of-related old post I did find was "Improper Installation May Yield The Fastener", which certainly captures the sense of what I was feeling I had when I broke off a bolt using a torque wrench. Anyway, no matter what I tried, that broken bolt refused to come out. So rather than totally destroy the stem trying to remove it, I chucked it into the "may fix someday" box, and went on with life.
Lo, behold, I recently came across this video by Youtube mechanical wizard AvE about using an alum solution to remove broken studs from aluminum heads, which seemed to have potential for my broken bolt stuck in an aluminum stem situation. There's another one where he compares alum vs nitric acid for doing the job (alum wins). AvE is a kind of genius mechanical hacker from Canada, and I thank him for this information, in addition to his awesome "BOLTR" (Bored Of Lame Tool Reviews) teardown videos. His language is salty, but his engineering and machining is inspiring.
|Before picture, broken off face bolt on the right|