Sheared Allen Bolt Help

[bpsmith]

My mates rear wheel was not free wheeling properly, so went over to lend a hand as he wanted to ride in the morning.

Gently turned the Allen bolt on the hub collar about a quarter turn and heard that ping that nobody wants to hear. Sheared bolt. nothing could be done differently and no warning to take heed of, they were just too tight to start with and should only have been torqued to about 2.5nm.

Adjusted to make that it was the problem and freewheeling perfectly.

Swapped cassettes from his other wheels, so at least he can ride, but now just need to get the remaining bolt section out and replace the bolt. Any suggestions guys?

I know that the collar can be bought separately, but would prefer to get the bolt out if can be done...

 

[Pumpkin the robot]

Take it to an engineering machine shop and they will be able to drill it out. Should take about half an hour and cost about £15-20

 

[srw]

I can't actually identify the bit you mean but...

if it's standing proud, grab it with a pair of pliers and extract. If it's sheared off entirely inside the frame, use a second bolt of the same size to push it out.

Of course, if it's one of those fancy bolts where the hole is entirely embedded in the frame and there's no exit hold, neither of those suggestions will work - but nor would I want to trust a machine shop with a drill. I'd look at trying to find a way to get something that an allen head or a screwdriver can make a purchase on.

 

[bpsmith]

The hub collar is on the outside of the hub on the wheel itself @srw. I have the part removed from the wheel. The bolt is small and the bit protruding is way to small to grip. Not tried another bolt, but can't see it working on this occasion as there's no thread available to start gripping the new bolt.

 

[Globalti]

I haven't a clue what part you mean. Can't you post a picture?

 

[vernon]

There are device called screw extractors which can be used to extract broken screws and bolts. They do work but the cost of the drills and tooling might exceed the cost of the replacement part.

http://www.screwfix.com/p/screw-extractor-5-piece-set/18643#product_additional_details_container

 

[Yellow Saddle]

This sounds like the pinch bolt that locks the preload collar on something like a modern Campag hub? But I'm speculating.

If so, you have a problem. The bolt (machine screw rather) is so small that drilling is out of the question. If the screw's head broke off, the collar will be loose and can be removed. I suggest just keeping it in position with some Loctite, in that case and ditch the pinch bolt solution. Or, remove the entire collar and replace with a new one.
If the collar now cannot be turned, a dremel cut-off wheel can be inserted in the slot and the bolt cut off, which will then lead you to the previous solution.

I have a feeling though that my solution may not be for your problem. In that case, just keep this advice as a spare for now.

 

[bpsmith]

@Yellow Saddle has the right part in mind. Fulcrum wheels, but probably similar part to Campag, bring in same ownership.

As already stated, the part is off the wheel now, so new collar is certainly an option. Was hoping that there may be a quick fix, so he can get the wheels back on, but appears not. Will enquire in LBS at lunchtime regarding new part.

 

[fatboy123cycling]

Repair will depend on the cost to replace. Depending on the diameter and condition of the bolt - it can removed with a stud extractor - this means the bolt will need to be drilled 'dead' centre, and a stud extractor used - this is a hardened thread like tool with a left handed flute. Another way but expensive is spark erosion - but this would only be used to save an expensive part

 

[Pumpkin the robot]

I am a toolmaker, I have had so any of these sorts of things bought into work that someone has tried to get out and made the job twice as hard because they have tried to do it themselves and made a complete mess of it. Take it to someone that does this sort of thing all the time. They will be able to advise you what needs to be done and how much it will cost. Drilling it will only be a problem if the screw is loose. I have drilled 0.25mm holes before and I cant see it being smaller than that.

 

[Yellow Saddle]

I have drilled 0.25mm holes before and I cant see it being smaller than that.

Wow! How do you do that? What tool is used for such a little hole? Can you post a photo of it?

 

[Turbo Rider]

I'd go with the loctite solution, but it can be tricky and you might end up gluing the whole lot together if you're not precise - best to put the glue on the key, rather than the bolt in the case, but you'll need to be fast in getting it in. You could also try holding a rubber band over the hole and seeing if you can edge the allen key in slowly enough that it doesn't bore a hole through it and then turn, as this will reduce the gap - actually very tricky to do this though and will lead to cussing.

 

[Deleted member 26715]

Used to work for Dormer drills many many years ago, story went that some American's came over to visit the factory & setup, at the first meeting they gave the MD a present, the worlds thinnest drill bit, as they were about to leave a couple of days later the MD announced he had a leaving present for them, he gave them their own drill bit back with a hole all the way through the centre. No idea if it's fact or fiction but it was always told around the factory & it was when England was the engineering capital of the world. Sorry if it's a bit too far off topic.

 

[raleighnut]

Used to work for Dormer drills many many years ago, story went that some American's came over to visit the factory & setup, at the first meeting they gave the MD a present, the worlds thinnest drill bit, as they were about to leave a couple of days later the MD announced he had a leaving present for them, he gave them their own drill bit back with a hole all the way through the centre. No idea if it's fact or fiction but it was always told around the factory & it was when England was the engineering capital of the world. Sorry if it's a bit too far off topic.

I've heard a similar tale but the drill they used was left in their drill.
To answer @Yellow Saddle You would use a drill You can even gets taps in order to thread holes that small, Watchmakers use them all the time or did you think that those little screws were put in by elves.

 

[Tim Hall]

If the bolt isn't under tension (and it's unclear from your description whether or not this is the case), you might have success by gently tap tap tapping the collar with a small hammer and letting the vibration unscrew the busted bolt.