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

[keithmac]

I drill bolts out almost every week, wouldn't fancy drilling down the middle of a 2mm allen key!.

If you've smudged it round in the bolt head as well then good luck!.

Maybe a few taps head on with a punch to try and free it up then the magnet?.

 

[randynewmanscat]

Ahhh.... It is a steel screw yes? The key snapped rather than turning into ornamental miniature scroll work which suggests it is hard (and very poorly tempered). You may have trouble with a freehand setup.
Handling a cordless drill with a 1.5mm bit trying to cut hard materials is a nightmare, I've done it on silver steel dowel pins at some weird angle with an uncomfortable posture and barely got away with it, the bit usually snaps at the tip.
You could leave it until its time to adjust the cable then cut the cable and find someone with a bench drill and drill vice then attempt to drill the head and turn a ST screw in and yank out. It might be worth trying some taps on the back face of the thing first, if the socket is clean it might spit the key out.
Again if the socket is clean and the key not burred (which is unlikely if it snapped off) you could start gently by offering a rare earth magnet to it, it might just fly out, or not.
You don't need telling twice but I will just to be an irritant, buy some better keys. Thoroughly reading the thread I see you are on fingers crossed as you think the snapped key may have cammed onto distorted flanks in the socket.

 

[randynewmanscat]

One of the blokes at work is bringing in a Neodymium magnet tomorrow

Ah, I didn't see that, keep your fingers crossed. I was frightened by the power of these things, I dropped one in my yard which is ornamental pea gravel, when I picked it up it was encrusted by gravel. I never knew there was so much iron in various different stones.
Oh, watch your fingers, they take no prisoners, you are going to exercise caution if its anything like a 50x50x15mm magnet, it will find some iron if you let your guard down for a millisecond.
Good luck.

 

[randynewmanscat]

Mmmm, may not be strong enough! Worth a try, then maybe order an earth magnet from Amazon, you could have it delivered to tomorrow, the you’ll have it when the rest of the hex keys snap...

He could order decent keys at the same time

 

[randynewmanscat]

the broken off key is a couple of degrees clockwise of the female head (therefore jammed)

If the key has cammed against slightly deformed flanks in the socket I fear for the magnet method. Trying to back it off the cam will be a lesson in extreme patience and tools smaller than you or I have to immediate hand, you may find that the tip of a pin looks very big when you try to probe for a gap to lever within.
If you was my neighbour I would spot tack a 1mm wire to it with TIG and pull it out.

 

[Gunk]

would spot tack a 1mm wire to it with TIG a

Probably the only method that will get it out

 

[DRM]

Try tapping the broken off ball end of the hex key at the bottom, see if it rotates towards you, then you may be able to get something behind it to prise it out, or grip it with some pliers

 

[randynewmanscat]

Probably the only method that will get it out

Its frustrating that people you would be happy to help (he rides bikes and posts here) aren't a short drive away. A friend laboured over a frozen seat post last year and did not ask me. Was a steel frame, he tried everything YouTube had to offer and failed miserably, eventually he asked if I had any ideas.
The frame was already well scuffed about so I just burnt it out, took about 4 minutes, I asked him how long he had been making feeble attempts to 1st haul on the head with stilsons, 2nd marinade it in various solutions, 3rd cut the head off and attempt to rasp and use a 13mm drill as a mill, he refused to answer.

 

[rockyroller]

would gravity help? meaning turn the bike in such a way that the broken bit is facing the center of the Earth. whatever you try gravity could only help, no?

 

[JhnBssll]

Dot punch to loosen then grab a hot melt glue stick, heat the end up with a lighter and squish it on. Wait a minute then pull it off. Realise it hasn't worked, go back indoors and make a cup of tea.

 

[Lovacott]

You could leave it until its time to adjust the cable then cut the cable and find someone with a bench drill and drill vice then attempt to drill the head and turn a ST screw in and yank out. It might be worth trying some taps on the back face of the thing first, if the socket is clean it might spit the key out.

It's not the cable clamp bolt which is damaged. The Shimano 105 clamps the cable to a rotating clamp which can then be adjusted with another screw which pushes the rotator around to tension the cable. It's that screw which has the problem.

It's still possible to get the tension right without using the screw simply by pulling the cable tight and then clamping. I'd have to have a few goes to get it right but at the moment (as luck would have it), the tension is bang on correct.

 

[randynewmanscat]

It's not the cable clamp bolt which is damaged. The Shimano 105 clamps the cable to a rotating clamp which can then be adjusted with another screw which pushes the rotator around to tension the cable. It's that screw which has the problem.

It's still possible to get the tension right without using the screw simply by pulling the cable tight and then clamping. I'd have to have a few goes to get it right but at the moment (as luck would have it), the tension is bang on correct.

I know, it took me a while and a proper read through to realise, that the key was only 2mm should have been enough information. I assume you will get to try your friends magnet later today.

 

[Lovacott]

I know, it took me a while and a proper read through to realise, that the key was only 2mm should have been enough information. I assume you will get to try your friends magnet later today.

Got it now.

It's so strong I've put it into a box wrapped in tissue just to stop it getting stuck to anything before I get home.

About four hours from now, I'll know whether or not it works.

 

[Ian H]

Hold the bike so the bolt is facing downwards and tap the bolt head to loosen the trapped bit of key. No guarantees.

 

[T4tomo]

So a fiddly 2mm bolt is progress from a simple to use inline adjuster??

I assume its all internal cable routed. Do you have a suitable cable stop to retrofit an inline adjusted if needed, would save having to junk the front mech if you cant get the broken bit out??