help! - snapped bolt stuck in aluminium casting

JohnTH said:
I had to have a snigger at the thought of someone trying to drill out by hand something hard from something soft. Difficult or what!
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I've drilled out three or four steel bleed nipples out of aluminium alloy brake callipers. It helped that the nipples have the bleed channel straight down the centre of the nipple, because that ensured the drill bit was dead centre. I used increasing diameter bits to increase the size of the hole, until little more was left of the nipple than the threads. Then used a chisel to smash the remaining 'shell' of the nipple inward, then picked it out with pointy pliers. I've done likewise with snapped bolts, but it's more difficult to ensure the drill bit is centralised and parallel to the bolt axis. It usually means leaving a thicker 'shell' and then a lot heavier blows to the chisel to crack the remaining bolt inwards.
 
If all else fails you should be able to save the head with spark erosion. Not cheap but it has worked well for me on various old motorcycle bits. You may need to remove the head but there are firms who do this on site - a quick look on google shows 'spark eroding.co.uk' in Lancashire. I don't know where you are but there may be others.
 
JohnTH said:
I had to have a snigger at the thought of someone trying to drill out by hand something hard from something soft. Difficult or what!
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Well if you don't operate the "Too Difficult File" system and are a reasonably accurate worker it is the simplest method.
It is often the last chance you have.
 
In the past when I was a bit more involved with 'heavy metal' we used 'eaziout' a lot. Tried google but no luck, do they still exist?

You drilled a pilot hole in the broken bolt/stud and then screwed in the correct sized eaziout, a tapered hardened left hand thread dooh dah, almost always worked.
 
No not TOO difficult at all however, in the context of a broken bolt stuck and in an aluminum head that is still attached to an engine, the prospect of drilling it out by hand is a difficult task. Oh, and this is assuming that the object is to cause as little damage as possible.

On the other hand, in a workshop, it is still difficult but not too difficult.

Yes, I agree that it is often the only chance and have spent hours and hours on similar broken and or stuck items.

Hope kashirst has the bolt out by now.

72s de

Johnth
 
kashurst said:
Help - bit of a disaster, I have managed to snap the head off a bolt whilst trying to undo it from an aluminium alloy cylinder head. Most of the bolt is still sticking out, Tried molegrips and heat but no luck. I don't want to take the head off and have it machined out unless absolutely necessary. Any suggestions gratefully received.
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If it's stuck, due to corrosion, don't use oil, but use a weak dilute acid - vinegar is OK.

The acid dissolves the hydrated aluminium oxides, on which oil has no effect.

Leave the acid standing on the item for about 24 hours than try heat and brute force.
 
capnsensible said:
In the past when I was a bit more involved with 'heavy metal' we used 'eaziout' a lot. Tried google but no luck, do they still exist?

You drilled a pilot hole in the broken bolt/stud and then screwed in the correct sized eaziout, a tapered hardened left hand thread dooh dah, almost always worked.
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Yes, wonderful things. :p

I got a bolt out with one once. Every other time I tried to use them, they snapped, ensuring that drilling the bolt or nipple out is simply not going to happen by fixing a piece of steel that's harder than the average drill bit right where I ned to drill.
 
Nitric acid

charles_reed said:
If it's stuck, due to corrosion, don't use oil, but use a weak dilute acid - vinegar is OK.
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I remember many years ago having a problem with a tap that had broken off in an aluminium alloy casting. Our workshop dealt with it by treating it with concentrated nitric acid diluted 50-50 with water. The nitric acid produces an oxide layer on the aluminium rather like anodising, but dissolves the steel. Conc. nitric will passivate the steel as well, so it must be diluted.

It works, but be careful. Conc nitic acid is nasty stuff!
 
If you've got plenty of stud, then i'd thread it and weld a nut onto it, or double lock nut it. Lubricate well with proper penetrating oil and leave overnight, use gentle heat at the base, then just ease it back and forth ever so gently without too much force. It will give eventually, lots of penetrating oil, heat and movement will get you there.

Drilling accurately into a stud is damnable difficult to do without doing other damage, and its So easy to knacker an alloy head if the drill slips off centre.

Remember the old engineering saying "Little knocks can move great rocks, where bigger knocks will break them"..Its true as well

Good luck

Tim
 
I had success removing a bolt that a previous owner had rounded the head on it. I flattened the sides with a grinder and clamped a vice on to it. This gave me enough leverage to undo it.
 
Maybe the OP has buggered it. He's not replied or been back on to tell us his progress
I have a number of suggestions but will not bother to go further if im just going to waste my time.
 
Meanwhile,over on MOBO thread.........
thanks for all the ideas. I welded a length of threaded stud onto the broken bolt. it all tightened up OK so fingers crossed. I will try the wonder wheels trick in future
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PS Good quality Easi-Outs in the right hands are a wonderful thing!
 
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On getting heat to the job.

Oxy/Acetylene or Oxy/Propane is far more effective than a blowlamp.

If you drill it it's possible to heat it with a soldering iron with the bit removed. With the correct choice of iron with a parallel element and hole size plus some grease.
It's also possible to use a copper rod in the same way. It gets the heat right down to the end of the stud.
 
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