Stainless Steel fastener in aluminum mast

[Disielcustoms]

I have a few stainless steel ubolts that just don't want to come out of the mast head. Tried some products to loosen the corrosion and some hammer persuasion but no joy. What trick or products have u found to be helpful in this case?

[Breaking Waves]

There are various types of penetrating oil - you usually need to soak them in for a day or more

Impact - can loosen it

and Heat (quite a bit)

Often you need to combine all three

rarely, it just will not come and you just have to cut/drill the bolts out.

[JPA Cate]

Jim has has excellent results using the "weasel piss" from here on CF: combine equal parts automatic transmission fluid and acetone. Let it sit overnight. Then use the impact driver. You may have to try again, and you may have to heat it, but you are likely to be able to get them out. On re-assembly, remember to use a good anti-seize product.

Ann

[billknny]

Cycling hot and cold has never failed for me. Heat the screw as hot as you can--really hot--with a propane or mapp gas torch. Then drown it in cold water. If it won't come out, repeat. I have never had to do it 4 times. For SS stuck in Al, I have never found a penetrating oil that worked well enough to make it worth the trouble.

What happens when you run the torch on it is the screw heats up and expands. Al conducts heat very fast, so it never gets as hot, even right at the torch flame. When you douse it in water, everything very quickly shrinks. The differences in rate of expansion and shrinkage breaks up the corroded Al that is holding everything together.

A good impact wrench can help. Not one of those silly things you hit with a hammer, but a proper air or electric impact driver. But if you temperature cycle it will come out with hand tools, assuming the head doesn't fail first.

[Jim Cate]

I must post a bit of correction to Ann's post above (sorry, Ann).

First, while weasel piss is great stuff, it isn't appropriate for this problem, nor is any other penetrating oil. Just doesn't work in stainless/aluminium seizures which are mechanical in nature.

Second, since the items that are frozen in place are U-bolts, attacking with an impact driver isn't appropriate either. One could be of use to remove the nuts on the U-bolts, but I don't think they are the problem... it is getting the bolts themselves out of the alloy casting that is the issue.

IMO, the only useful approach will be to heat the hell out of them and then drive them out while everything is still smoking hot. It may take repeated efforts, but if you get the casting hot enough it should eventually come good. If possible you should support the casting while beating on the bolts, for there is a danger of breaking off the tang that the bolts go through (I'm guessing here that the bolts are in the horns sticking forward for the spinnaker halyard(s)).

Good luck, mate... this could be a tough one!

Jim

[JPA Cate]

^^^^^ Thank you, Jim.

A.

[Disielcustoms]

Jim that is exactly where the u-bolts are and they hold the spinnaker block. I wounder however if applying all that heat might weaken the aluminum horns? Doesn't alum weakens when welded or heated that much?
thanks for all the replies

[Jim Cate]

Well, cast aluminium is fairly heat tolerant AFAIK. I've done the heat and beat thing on quite few alloy castings and have not had any later failures, but that isn't proof that it could not happen. However, I don't think there is any other solution to the problem.

BTW, is the mast out, or are you trying to do this aloft. If aloft, its a really hard row to hoe, both in terms of heating and beating.

If a few cycles of H&B don't shift it, it could be helpful to saw off the U and use a punch to drive one side at a time. Getting the force of the hammer blows to act equally on both sides of the U at once isn't gonna be easy.

Wish I could be more encouraging, but that could be a tough nut to crack!

Good luck.

Jim