Originally Posted by SouthArk370Z

Found a neat trick. If you break off a steel stud, bolt, tap, etc. in a piece of brass or aluminum, here's a great way to get it out. It's slow, but it works.

Get some potassium aluminum sulfate (AKA alum) at the grocery store - it will probably be in the canning section.

Set up a double boiler and add about 1 oz of alum per cup of water. Heat up the boiler and add more alum until the solution is saturated (no more alum will dissolve).

Dunk the part in the hot alum and let soak for several hours to several days (depending on the size of the broken part, what kind of steel it is, concentration of solution, and temperature). The hot alum will corrode the steel part but not the brass or aluminum.

I have tried this with a brass manifold from a Coleman lantern that had a stud broken off in it - worked great. Haven't tried it with any aluminum parts, yet.

Use appropriate safety equipment as you will be messing around with a hot, strong, alkaline liquid - goggles, gloves, ventilation, etc - it's not poisonous, but it will be very basic. If you get some of the alum solution on your skin, rinse well with cool water. I did it on my kitchen stove with the exhaust fan going.