Removing large bolts

[Andy Dingley]

They've probably got better access to big hairy Viking(sic) berserkers and Thor's hammer than uk.d-i-y does.

[Dave]

Can it be heated up again with steam?

Dave

[Steve Firth]

Ah, I suspect it's not going to work if there's only enough room for a socket. A breaker bar is the more traditional approach, but I thought that the repeated blows from an impact driver might be sufficient to break the corrosion and let the bolt move.

It sounds as if you're into Fred Dibnah/Eastleigh engine works territory. I would guess that there are people with the experience you need, but I'm not one of them. We have a local steam railway that has its own engine sheds and I have a ex-schoolfriend who owns traction engines (and who once owned the Flying Scotsman) do you want me to see if any of those has the appropriate experience?

[Matty F]

Not for a few months. A real engineer is gettng the bolts out, but he'll have to make some new ones as they are getting damaged.

[Matty F]

There are people around here who work on steam engines. One of them has said that the bolts were not really intended to come out again, and that we should try to hone out the cylinder in situ.

There should be room to fit a breaker bar. Perhaps I could try a longer bit of pipe on it, but I don't want to damage the socket.

looks simple enough doesn't it?

[Steve Firth]

There's many a road to disaster that has started with "how hard can it be?"

[Peter Parry]

Everyone knows it is the 5 minute jobs which take 12 hours.

[Dave Liquorice]

He he, like the "real engineer" that is removing the bolts but damaging them in process. Sounds more like any other bloke that has looked at this problem but has a bigger hammer. B-)

[The Natural Philosopher]

weld a bar onto them and knock it with a big hammer.

Standard engineering practice ;-)

[Jules Richardson]

Are you able to try an air-driven wrench? Someone else mentioned vibration, and IME that's often the key with these kinds of things - force alone won't do it. I was trying to free a corroded heating element a few months ago, and even 6' of breaker bar wasn't moving it.

Silly question, but I assume that you know for sure that these particular bolts aren't threaded all the way down the shaft, with "internal" nuts holding them in place? That might explain why they aren't turning and why the puller (well, pusher) didn't work. I realise that your "example" bolt wasn't like that, however, and just had threads at the end.

Is the plate that's held down by the nuts at all sacrificial - i.e. can it be re-made relatively easily if you end up having to destroy it simply to remove it? If it were gone, maybe you'd have more options.

cheers

Jules

[Matty F]

I'm told that with a really big breaker bar the head of the bolt would turn while the other end wouldn't.

All the bolts are the same. They've been in place for 120 years and are a really tight fit.

Definitely not sacrificial. The bolts can be remade. I have suggested making a very large clamp with a 10 ton hydraulic jack within it.

[Andrew Mawson]

things -

"example" bolt

Differential heat and penetrating oil is the solution. The old trick was to get a large rivet white hot, then press it against the end of the stuck bolt until it cooled to dull red - then do it again!. Liberally feed penetrating oil into the interface. Do this over several days an it'll eventuaslly shift. The idea is that by heating the bolt you expand it relative to whatever it's in, and as it cools the penetrating oil will penetrate. If you just play a flame over the bolt you heat both the bolt and it's surrounding an get no differential expansion.

BTW an excellent penetrating oil is a 50/50 mixture of cheap ATF and acetone. Put them in a hand spray bottle and shake well before you spray, as they don't mix but form an emulsion.

The basic issue is that rust takes up more volume than the original steel, so a rusted bolt is fatter than a clean one.

AWEM

[Matty F]

But the bolts don't seem to be rusty:

've been bolted up tight for 120 years while holding many tons of steel juddering up and down so that the bolts have welded themselves to the holes they are in.

[Dave Liquorice]

Wouldn't it be better to heat the sorrounding thus making the hole bigger or cool the bolt thus making it smaller? Got access to liquid nitrogen Matty? (*) Dribble some over the exposed end of the bolt, but don't go hitting anything when it's super cold! Freezing your penetrating fluid might be a problem as well. B-) Maybe it would thaw before the bolt had expanded back into the hole?

(*) Or perhaps a pipe freezer kit?

[Matty F]

We have some kind of cooling spray. I'd be inclined to use my clamp idea, heat the surrounding area and apply ice or the cooling spray to the end of the bolt, and hit the end of the clamp with a sledgehammer.

[Peter Parry]

the right half of that bolt .

It is fretting corrosion, damage induced under load and in the presence of repeated relative microscopic surface motion caused by vibration. Pits, grooves, and/or oxide debris characterize this type of corrosion typically found in machinery, bearing assemblies, and bolted components. One effect is to cause the parts to bind together.

[Spamlet]

I do similar but get both the bolt and the surrounding metal hot and then spray the hot bolt/nut ends with the coolant/penetrator oil. Often had been the final solution - and worked satifyingly, though the hot 'WD40' fumes are not pleasant...

S >

[Spamlet]

Me too: good luck.

S

[Spamlet]

Did you try shocking the nut end of the G clamp while you had the pressure on? Looks like you got a better grip, than I'd have expected from your second picture.

S

[Spamlet]

With a bit of care, and if there is enough room (looking possible as you were able to get the clamp on), you could try drilling and tapping the bolt head (but tap not wider than shaft or the head may break off) for a bit of threaded rod which you could then use as the basis of a slide hammer. You might want to weld the rod for good measure - but then you'd need to make two...

Drilling the bolt right down the length would make it easier to apply coolant too...

Incidentally I still think your could apply pressure more easily by unscrewing the nut against a brace than by making the effort go all the way around the G-clamp from the other end.

You do come up with the most interesting brain teasers Matty ;-)

S