Removing a rusted bolt

[wolfie]

Some time ago, I mounted an internally-threaded stainless steel fitting in an exterior surface. To keep crap out, I put in a (normal steel) "grub screw" (intended to mount something to it fairly soon, but kept putting it off). Now I need to mount the device, but the grub screw is rusted in place. Yep, I should have mounted the device, or used a nylon or stainless bolt as the "placeholder", but it's too late for that now.

Brute force is not an option (tried leaning hard on the allen key, but it looked like the stainless fitting would rip out before the grub screw came out. Heat is a bad idea, since it would damage the surface the stainless fitting is mounted to. Haven't tried penetrating oil yet (gotta get some), but if that doesn't work, any ideas?

I had been thinking of "helping" the rust along (i.e. corrode out the grub screw) - substances I have access to are hydrochloric acid (used for cleaning concrete), sulphuric acid (plumbing clog remover), ferric chloride (PC board etchant), and a liquid rust converter (used before painting a rusted surface, but if you don't paint soon, the rust comes back really heavily). Which is probably the best to use?

[Bella_Vixen]

Coca Cola.

[Der Cute]

WD 40. Let soak for a few hours. Then turn.

[Mikkel]

I'll second the WD40.
Try heating a larger bolt and touch it to the rusted one, that way you'll heat the bolt without damaging the surface.
You could try drilling it out, use a drill a size smaller than the hole in the fitting.You will have to rethread the fitting to get the last out.

[Imprl59]

Get you a can of Kroil penetrating oil. http://www.kanolabs.com/google/ It's one of the few products n this world that actually works as advertised.

[Mikkel]

I like the Brunox Turbospray, I don't know how available it is in USA though.

[protege]

Brute force is not an option (tried leaning hard on the allen key, but it looked like the stainless fitting would rip out before the grub screw came out. Heat is a bad idea, since it would damage the surface the stainless fitting is mounted to. Haven't tried penetrating oil yet (gotta get some), but if that doesn't work, any ideas?

Some "3 in 1" oil, or WD40 should work. Just work it in around the joint and wait. BTW, is this grub screw one with a raised head? I'm wondering, since you can sometimes use a hacksaw to cut a slot across, and then use a screwdriver to remove it. The other method...is to get a pair of Vise-Grips, clamp them to the head, and twist. The last method...is a last resort. That is, either drill out the offending screw completely, or attempt to remove it with an extractor. The reason that those methods are a last resort, is they usually require re-tapping the threads. Plus, if you snap a screw extractor, it's a royal bitch to get one out!