Uh Oh. Snapped Off A Hex Key In A Bolt Head.

[Ming the Merciless]

Trouble is if OP has jammed the end of the key so hard that it snapped then a magnet or superglue is unlikely to help.
Dilling is best but the steel is hard, very hard. Either drill and fit a small self tapper or drill a 3.5 cm hole and jiggle the remaining bits out with a thin screwdriver or similar.

They say they just tightened it using a finger and thumb. So can’t be all that tight.

 

[flake99please]

If you have access to a dremel I would recommend cutting a small notch into the bolt. You should then be able use a flat blade screwdriver to remove it.

 

[Big John]

What Ming said - worth a try. Failing that you can get a set of bolt extractors from Screwfix. I've got some. If you're DIY savvy then they work like a dream. The smallest drill might be small enough for that bolt. However, once the bolt is removed you'll need a replacement.

https://www.screwfix.com/p/bolt-extractor-set-5-pieces/1112v

 

[Cycleops]

Dilling is best but the stel is hard, very hard.

I can bet this particular steel is more akin to cheese.

 

[Darius_Jedburgh]

They say they just tightened it using a finger and thumb. So can’t be all that tight.

Why did it snap? Sounds more like the key was lent on hard, and in some way has embedded itself in the hole. It takes a peculiar talent to do this🙄

 

[Darius_Jedburgh]

I can bet this particular steel is more akin to cheese.

But steel that is hard is more likely to snap than bend, or drill.

 

[Ming the Merciless]

Why did it snap? Sounds more like the key was lent on hard, and in some way has embedded itself in the hole. It takes a peculiar talent to do this🙄

I am sure ham fisted can’t have been there 😂

 

[Darius_Jedburgh]

I am sure ham fisted can’t have been there 😂

You might think that. I couldn't possibly comment.

 

[Lovacott]

Trouble is if OP has jammed the end of the key so hard that it snapped then a magnet or superglue is unlikely to help.
Dilling is best but the steel is hard, very hard. Either drill and fit a small self tapper or drill a 3.5 cm hole and jiggle the remaining bits out with a thin screwdriver or similar.

I don't want to try anything potentially destructive just yet. On very close inspection, the broken off key is a couple of degrees clockwise of the female head (therefore jammed). According to some, it's just a case of either rotating the broken bit back into line with a pin or waiting for it to vibrate out with use.

I've rounded off many a bolt head in the past but I've never had a hex key snap on me before. If it had happened with any other bolt on the bike, I'd have been able to remove the bolt with pliers and replace it.

But no. It just had to happen with the only bolt on the bike that can only be removed with a key.

 

[Lovacott]

I am sure ham fisted can’t have been there 😂

I was looking at the tension alignment lines and they were nearly bang on. I decided to add on a fraction of a turn to get them 100% in line.

Thumb and forefinger pressure only, then snap.

I've had the set of keys for years. Draper, probably mid 1980's and I can't remember ever using the 2mm key before.

 

[Big John]

Apologies if I gave the impression the bolt remover tool is potentially destructive. The tool itself is turned by hand in an anti clockwise direction and is relatively benign. It bites into the metal and as it rotates anti clockwise it unscrews the bolt. Out it comes. I've had a couple of 'miracle' moments when you see that bolt start to come out - it's a cracking little tool. The bolt may even be reusable but if it were me I'd have a replacement on hand just in case. I presume it's a bog standard bolt, even though it's recessed?

 

[fossyant]

TNT or new bike !

 

[Lovacott]

Apologies if I gave the impression the bolt remover tool is potentially destructive. The tool itself is turned by hand in an anti clockwise direction and is relatively benign. It bites into the metal and as it rotates anti clockwise it unscrews the bolt. Out it comes. I've had a couple of 'miracle' moments when you see that bolt start to come out - it's a cracking little tool. The bolt may even be reusable but if it were me I'd have a replacement on hand just in case. I presume it's a bog standard bolt, even though it's recessed?

Yes. Extracting the whole bolt would work and I'd be more than happy to try it. If I un-clamped the rear mech cable first, there would be no load on the threads which would make it easier.

As for a replacement, I'd say that it's the same thread and head size as a cross head limit screw on my old mech.

 

[gbb]

If it's a ball end key, I've had the same happen on good quality (Wera) keys, although mine get used daily. They snap at the weakest spot, the narrow point between the shaft and the ball end. Once was using it a bit excessively, once it just snapped easily so it does happen
Araldite, superglue, a magnet if you're lucky...I say lucky because usually the screw is steel so it kinda equally sticks to the screw as well as the snapped off bit.
Not sure about drilling ?...I'd have thought the Allen bit would be extremely hard...but I've never tried it so maybe ?
Otherwise, mole grips and remove and replace the screw.

 

[PapaZita]

If it really wasn’t under a lot of pressure then it probably isn’t very firmly stuck. I realise it’s small, but can you get a small punch on it, and tap it in the reverse direction? If you don’t have a tiny/sharp punch then maybe a small nail or screw?