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PostPosted: Sat Aug 03, 2013 10:58 pm 
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Joined: Fri Dec 28, 2007 10:57 am
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Location: London
Having today acquired a 97 Kilauea from rojo, in my eagerness to throw it all together again the bolt to tighten the headset snapped off, with the headset too loose to ride as is. See photo below! :facepalm:

So now I have a very nice classic steel MTB and a wobbly front end, with no way of tightening it.

I do have a screw extractor thing I have never used- anyone got experience of doing this and is it the best option? Its the only one i can think of really...

Cheers


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PostPosted: Sat Aug 03, 2013 11:11 pm 
retrobike rider
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I'm sure the instructions for the extractor will mention drilling a pilot hole into the snapped end ; just be super careful that the drill doesn't jump about and ruin the top ring. If you have a good punch I'd recommend making a pilot for the pilot if you get me.


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PostPosted: Sat Aug 03, 2013 11:16 pm 
Gold Trader
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Location: Gorleston-on-sea (If there is a bright center to the universe this is place furthest from it
Some sets come with a pilot drill which is a reverse twist so use the drill going backwards, if you don't have one of those smallest drill bit you feel comfortable using and turn the speed on the drill way down slow and easy takes it :wink: :D


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PostPosted: Sat Aug 03, 2013 11:40 pm 
Old School Hero

Joined: Sat Jan 01, 2011 11:14 pm
Posts: 219
Location: Wolverhampton
Hi, all the above is good, drill needs to be sharp, keep the drill "square" to the bolt, get someone to watch if necessary, once started a drop of oil (or proper cutting paste/fluid) on the end of the drill may help, take it steady and be prepared to stop if the pilot wanders off.
Hope some of this helps.
Regards Kit. :)


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PostPosted: Sat Aug 03, 2013 11:43 pm 
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Joined: Sun Apr 25, 2010 10:07 pm
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Ive drilled out many snapped bolts,its a pain.You will have to punch the centre of the bolt,start with a tiny pilot of 2 or so mm,plenty of coolant and graduate from 2 to 3mm and try to extract,if its a 6mm bolt and its impossible to extract, drill 4.8mm and run a 6mm tap through it.


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PostPosted: Sun Aug 04, 2013 12:03 am 
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Thanks for the advice... will be very careful!
:D


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PostPosted: Sun Aug 04, 2013 12:48 am 
Old School Hero

Joined: Thu Jun 10, 2010 4:46 pm
Posts: 159
Location: Salt Lake City Utah USA
Another approach...

Use a dremmel with a narrow cutting wheel and make a slot for a flat head screw driver, I bet it comes out in seconds..


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PostPosted: Sun Aug 04, 2013 5:06 am 
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On this type of headset the bolt is visible at both ends. I would start by drilling out the threaded end of the bolt. By removing material from this area you are 'undermining' the stuck thread and this will help relieve it and allow it to turn more easily. Use brand new tiny diameter drill bits, be patient and work up through every size until you've drilled out almost all bolt material - it's an M5 thread so the very most you can drill out is 4.2mm but you might not be drilling perfectly straight so be careful beyond 3.5mm and probably stop at 4.0mm. If you use a 4.5mm drill bit you will be removing female thread from the headset clamp-ring. To check whether you're damaging the female thread (by off-axis drilling for example) you can test the swarf with a magnet because on a Kona Impact heaset the bolt is steel and the headset clamp ring is aluminium.
Once you've achieved this you could try to get a purchase on the snapped end, either by drilling out and using a thread extractor or the methods suggested by others on here. Before trying to unscrew it, heat up the aluminium clamp-ring either with a heat gun or trickle very hot water over it until it heats through, then blow off the water and put some light oil or penetrating fluid around the thread areas. The idea is to get every possible advantage working in your favour before even attempting to unscrew it.
If none of this works it means the thread is tightly seized. You might still have a way out: The clamp-ring has a slot and if you could maybe insert a junior hacksaw into the slot and cut the bolt in half. The 'sheared-head' half will then just fall out leaving just the seized half which you then extract from the other side. A 4.0mm drilled hole will enable use of a thread extractor.
Personally, if none of this works i would probably replace the clamp-ring but if you're desperate to re-use it you do still have options:
The following ideas are less desirable but will probably still work and at least let you salvage the headset. You drill out the above mentioned seized half of the bolt to 4.5mm. The remnants of the bolt thread will now just fall out or you can use a tap to just clean out the female thread. Assuming you drilled straight, you've lost a tiny bit of aluminium material but not much (only nominal 0.15mm) and the cleaned out thread would still work with a new M5 bolt. This might have people saying "that's dangerous etc" but actually not, remember it's just a clamp lock to stop the ring from rotating, it isn't holding your fork to the bike and doesn't need to be tightened by a gorilla. Failing all this you could still try drilling out the whole thing and re-tap for M6 or just use a bolt and nut, otherwise you'll have to replace the clamp-ring.


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PostPosted: Sun Aug 04, 2013 10:44 am 
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Joined: Tue Dec 04, 2012 6:15 pm
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Is it possible to remove the clamp from the bike? (I've not used that type of headset before) if you can it's definitely worth mounting it in a bench vice to hold it still whilst you drill it.


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PostPosted: Sun Aug 04, 2013 10:54 am 
retrobike rider
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Very fiddly job, take your time.

I would replace it,ask around for a spare. If it is fixed on, hacksaw across bolt.


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