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Broken Bolt


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I have managed to snap the head off one of the bolts used in attaching my bonnet strut kit. Any ideas on how to remove it ? This is a bolt that I had just screwed in, it's not an old bolt rusted into the hole.

There is still a reasonable amount of the thread sticking up above the hole, but I have tried and failed to get some mole grips to lock onto it to let me turn it.

From looking around on the Internet I've seen one suggestion of filing down the sides of what is poking out to give me a flat surface, to give me more purchase to grip it and turn it.

Any other ideas ? Not really looking forward to trying to drill it out, since I've never done that before.

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What about putting a grove in the so you can screw it out?

but i must agree with Aaron drilling it out is the best option.

Centre punch it well then start small and build up slowly till you can get it out, hopefully with damaging the original thread.

Stav

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Tried the Dremel/unscrew method, it didn't work. Easy enough to make the groove with the Dremel, but the bolt wouldn't budge, and I ended up shearing off more of the bolt.

I will see if there is enough room to file down the sides and use Mole grips, but given how it seems to be stuck fast, I think I'm going to have to drill it out.

I've seen mention of those "Easy Out" extractors on some web pages, with people saying they often end up breaking those too.

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Yeah, I think those extcactors are okay for larger bolts, but we are talking 10mm here which is pretty small.

Steve, I remember having a small stud snap off in a VW camper engine block (Don't ask!!!!!)......and was a bugger to get at, tried 3 different Mole Grips. Finally I went to a garage and the guy leant me a pair of Mole Grips, but they had Long Jaws like a pair of Long Nose Pliers. When used on their side they allowed me to get a better grip on the broken stud as opposed to the standard Jaws of a normal pair of Mole grips.

Like this:

pp-gmlna.jpg

Keith

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If there is enough sticking out I would go for filing flats on it.

File until you can get a tight fitting small open end spanner on it

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I had a similar problem recently and used a sonic screwdriver I borrowed off Doctor Who, it got the bolt out but the car now keeps disappearing down worm holes and the AA have warned me that they will not recover it from Pluto again this year!

Sorry no help at all just a bit of lighthearted humour which may put you in a more positive frame of mind when trying to extract the bolt remains.

post-12144-1239567289.jpg

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Hmm, if the thread wasn't right in the first place and I ended up cross-threading it, that would explain a lot ! :nugget:

How to I re-tap a thread ? Do I need something like this ?

040210035.jpg

where abouts are you stevie

you are always welcome to pop up mine, got the tools if you need them

i am about ten minutes away from the grasshopper

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Don't try the "easy out" stud extractor, they are useless. You will end up with a case hardened bit of metal in the middle of the bolt you will have to drill out!

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Mac - yeah, I've seen lots of comments very similar to yours about those extractors. Is that even if you do it by hand though ? Or just if you use a drill ? I've seen stuff saying that using a drill with them is why they get stuck.

Bazza - I'm by the border of Hants and Berks. But popping over your way is a tempting option !

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Don't try the "easy out" stud extractor, they are useless. You will end up with a case hardened bit of metal in the middle of the bolt you will have to drill out!

if they break then it is purely down to operator error. Of course it helps to have decent easy outs in the first place rather than the el cheapo set for 20P in the local pound shop.

i have only had to drill thru and retap 1 bolt so far and that was a M12 bolt , all other screws and bolts have been removed.

if you still have some of the bolt sticking out then as suggested try a GOOD set of mole grips as tight as possible - i wouldnt try this if u only have a few mm of bolt showing, as nomally the grips will just end up chewing the end of the bolt.

maybe the best option is to grind the end flat then drill it out and retap if the original bolt is really solid and refuses to move. if its a 5mm bolt i would use a drill slightly smaller maybe 4.5 or 4.6 then run a M5 tap thru and see if it clears the hole..... alternative is to retap using a M6 tap set so you have enough material remaining for a decent thread.

did the bolt go in very easily?

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Nope, the bolt went in with a lot of trouble, which with hindsight is obviously a lot to do with the problem. It's a 6mm bolt.

I could probably do with a set of decent mole grips, even if trying them doesn't work. The set that I've got are pretty poor. There are only a few mm of the bolt showing, and now it's more fragile because of my failed attempt to get it out via cutting a slot and unscrewing it. Pretty sure I'm going to have to drill it out now (or use an extractor tool).

Steve2006 - loving the sonic screwdriver idea. Could you pop over here in your Tardis please and lend me that ? Or better still, nip back to when I was putting the bolt in to start with, and stop me messing it up ! :D

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ok so at a guess its cross threaded (as mentioned before) in that case drill it out and go oversize. make sure u can get another bolt to fit as M7 bolts is not a regular size. Alternative is to use a helicoil insert and keep the M6.

Although M6 is quite big, when you say "its a 6mm bolt" do you mean the thread size or the head size?

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ok, I'm a bit stuck now. I've been drilling it out, and I've done a better job than I expected of trying to keep the hole central. I've been increasing drill bit sizes as I've gone, and have worked my way up to a 4.5mm bit. I'm finding it difficult to make progress though, feeling like not that much is happening now in the way of cutting. I'm using some HSS bits, nothing expensive, just something out of Maplin.

I've got far enough for part of the top of the bolt to come away, though the rest is still stuck.

I'm loathe to keep drilling because I feel it would be easy now for me to start drilling away the sides of the hole in the bodywork without me realising it.

What should I do next ? Should I try putting a tap through it ? If so, what size ?

And yes, I do feel like an idiot for having to ask so many questions about this :tomato:

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