Seized bolts in Alu mast

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WayneS

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I need to remove some long bolts that go through my Alu mast foot which act as the spindles for the halyard sheaves. (I need to replace a couple of the sheaves which have broken)

They are a good 5" long but are corroded fast into the foot and I am weary of trying too hard to unscrew them for fear of shearing them off.

Anyone got any advice.

I am thinking that heat would do the trick as the alu would expand faster than the stainless bolts.

Regards

Wayne



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Lots of heat - have had the same problem at the foot of furling gear, and then apply pressure with a soft head hammer

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They are gripped as a result of electrolysis encouraging the oxidisation of the aluminium which has thereby expanded. Forcing it is probably more likely to damage the aluminium mast than the bolt. As well as heat, you might try dissolving the oxide with a mild acid like vinegar - I've even found a mix of vinegar and Coca Cola occasionally works. The difficult bit though is to persuade the acid to work in.

But often where aluminium and steel have been in contact a long while, shifting them is all but impossible.

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agree with AndrewB, your chances of getting them out without damage are slim.

i suggest you get on to the mast manufacturer and price out a new heel plug then you'll know how much brute force you dare apply!

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Just be glad it wasn't your nuts.

Sorry, couldn't resist it.

I think heat and brute force will be the best bet. I once freed one off through a goose neck fitting with penetrating oil, then (after a day or two) warming the immediate area with a heat gun and gently rocking back and forth with a spanner, withdrawing the bolt a little more with each rock.

I was pretty sure that the bolt would snap at times and I think I was lucky.

All the best.

<hr width=100% size=1>Think I'll draw some little rabbits on my head, from a distance they might be mistaken for hairs.
 
I had a similar problem - on a smaller scale - with a pulley block which fitted into the mast. Luckily, the block assembly could be removed from the mast, but the ali sheave was stuck hard on the stainless pin. Tried boiling water - nothing, then soaking in dilute acid - cleaned off external oxide, but did not penetrate into the 'axle'. Then overnight soaking in WD 40 - still nothing. Finally, heating with gas blow lamp did the trick. I think some of the WD 40 penetrated the gap between the pin and the sheave, so heat after a good WD 40 soak was the cure.

However, in my case this could all be done away from the boat. Presumably your mast is still stepped? That would eliminate the possibility of a blow lamp?



<hr width=100% size=1>KeithH
 
I had a problem with bolts into a aluminum windlass and posted here as yourself.

I also recieved the coca cola suggestion, laughed and tried everything else.

Getting nowhere I sat the offending bit in coke (I used Whites Cola I admit) for 48 hours and then managed to shift it.

Not conclusive - it could just have been cumalative etc but next time I will try it first..../forums/images/icons/smile.gif

<hr width=100% size=1>madesco madidum ..../forums/images/icons/smile.gif
 
Coca Cola contains citric acid, which is very good at dissolving stainless steel, and the oxides of both stainless and aluminium, which is why it is used in boiler cleaning in high pressure steam plants, turbines etc. I suggest that you visit your local chemist, Boots do small amounts for winemaking. Make a solution, and treat the bolts trying to use it in the same way as WD40, getting it to penetrate, and to remove the oxides which are causing the problem. You will need to do serial applications, between visits to your local hostelry. I know this sounds a bit simple but also make sure that your rigging screws are loose, to minimise down pressure on the mast. You can of course try heat as well, but this is the last resort as it may well anneal the aluminium mast

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As a grumpy old sad git (see other thread for more detail) I was in a pub, on my own doing the crossword (Telegraph fwiw) when I happened to overhear a chemist telling his drinking partners (hope you're keeping up with me here) that Ammonia is very effective at removing Aluminium from Iron and Steel.

Any chemists around care to comment?

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If the soaking doesnt work drill them and try an easy out. If that doesn't work drill as big as you can, then collapse the remaining using a punch or small chisel

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It's a little bit of an urban myth I'm afraid. The citric acid content of coke is less than you'd get in an orange, and the phosphoric acid content even less.

You'd be better off squeezing a lemon on, than using coke.

<hr width=100% size=1>Me transmitte sursum, caledoni
 
It depends how much aluminium there is. Ammonia will initially attack aluminium, but quickly forms a protective coating. Only a very very thin layer would be removed.

<hr width=100% size=1>Me transmitte sursum, caledoni
 
Now, why did I expect you'd answer Brendan?! I'll file that somewhere, but do you think it might be useful in breaking a cold weld such as the one under discussion? Or just an aesthetics thing?

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As another poster has alluded to you can only apply very low levels of heat to aluminium without risk of changing its structure reducing its strength, and such low heat levels are unlikely to solve your problem.

I am sure some cool cat will jump all over me for having that view but I don't much care.

I am aware of part built aluminium vessels that have been scrapped by the insurers because they have been close to, but not directly involved in, shipyard fires - purely because of the radiant heat they were exposed to changing the structure of the aluminium.

I would not heat an aluminium mast to the extent needed to loosen anything seriously jambed without direct professional metallurgical involvement and in my view any contrary advice is ill informed.

John

<hr width=100% size=1>I am the cat but I am only 6.
 
Re: bolt remover.

owners of busted old cars and bikes often have to drill out a bolt, but there is a special tool for the purpose. Essentially, you drill a pilot hole in the bolt, then screw in a tapered screw which has a left handed thread.

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If the crevice down between the two metals is sufficient to allow liquid down between, then it will work, sort of. It's not likely to work on a tight bolt.

<hr width=100% size=1>Me transmitte sursum, caledoni
 
Hi Woofy, my bolt was stuck in the boom end casting at the gooseneck and I think I was very lucky to get it out without shearing. I am pretty sure that it was the copious quantities of penetrant, applied over good period, rather than the low level heat from an electric gun, that did the trick, although the warming may have had some minor effect (straw that broke etc). It still took one of those make or break pulls to crack free, before it could be eased out as though tapping a new hole in reverse.

<hr width=100% size=1>Think I'll draw some little rabbits on my head, from a distance they might be mistaken for hairs.
 
The best way to heat the mast is hot water. The best cheapest penetrating oil is diesel. If you hit the end of the bolt you will rivet it in. the bolt will become shorter and fatter. If it is a nut and bolt cut the head of the bolt off and tighten the nut, this will stretch the bolt and make it thinner. Could try a slide hammer. Easy outs always brake off and are impossible to drill out.

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FWIW....

The point about affecting the strength of the aluminium is well made, and I would 100% agree if talking about the mast extrusion, or anything made out of "high strength" alloys (6061, etc - <200 °C can affect solution hardening)

**but**

If we're talking about a bog standard cast mast-foot, it is probably an Al-Si alloy, relatively lightly stressed in the area concerned, and therefore relatively insensitive to localised heat, as long as you don't melt it.

As pointed out by others, the problem is corrosion between the Al and the bolt. By all means try moderate heat (hot water, etc.) and wiggling the bolt head. If you're lucky it might work. What ever you do, don't use an "eazy out" stud remover - these sometimes work where things are free to turn, but that isn't the case here. Also, try not to break the head off!

Soak with diesel or plus-gas (WD40 mostly evaporates) for several days, and if it still won't move, get someone to heat each end of the bolt VERY rapidly to red heat with an oxy/acetylene torch or similar (small oxy-propane ones can be bought in Halfords for about £30).

This sounds drastic, but the key is to get a LOT of heat into the bolt very rapidly (<10secs), then stop. The bulk of the aluminium casting, and the poor heat transfer from the bolt stop the alluminium getting too hot, as long as you're bold. It goes against the physics of it to heat the bolt, but I think we're just looking to break / disturb the mass of corrosion. As it cools, try to wiggle it / pound on it again. If it doesn't work first time, then it probably won't work at all.

This has worked for me when trying to remove steel bolts from aluminium motor bike bits in the past after all else had failed.

The last resort, and far harder than it sounds is to drill the bolt out.

Would be a good idea to protect adjacent GRP with wet towels before striking the torch....

Andy


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