HELP i've been an idiot - snapped stem bolt

Hi All,

I'd been searching for a well priced Factory 5 quill stem for ages so I can easily swap bars on my quill stemmed track bike.

Finally managed to find one and literally 5 mins after it arrived i'd over torqued one of the faceplate bolt that has snapped....Yes I'm an idiot. (In my defence thought it would need more than 4nm)

Any suggestions on how to remove the portion of the bolt that is snapped?

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Punch the centre, pilot drill it then use a screw extractor but start collecting herbs and goat skulls and shit first coz getting screw extractors to actually work is some black magic hoo-doo.

there looks to be a bit of a burr on the end of the broken bolt, try an small screwdriver on this area and with a hammer try and gently tap it round until theres enough protruding to get the pliers on it.

did this with with a bottle boss bolt.

While you may be able to centre punch and the get a drill hole to be able to get a "easyout" on to
the broken end it may well not work. Put the stem in boiling water to get it as hot as possible as the Ali will expand more than the steel.

Do not try to do this with a hand drill you need a proper engineers drill with a decent vice to grip the stem in.

The other way is to find company with a spark eroding machine and ask them to remove the broken part.

Thanks all so far have just managed to snap drill bits but am using an electric hand drill rather than a proper pillar one @lot14 any leads on somewhere with a spark eroding machine? The places on google seem pretty industrial to walk in with a stem.

any leads on somewhere with a spark eroding machine? The places on google seem pretty industrial to walk in with a stem.

Will cost more than the bike to get it done, very much an industrial process

something like £150 min charge

Get an automatic centre punch.
Keep the punch straight and punch a dot as close as you can to the circumference of the bolt.
Punch in the same place four or five times to deepen the dot.
Then place the punch in the dot, but keep it tangential to the circumference.
Punch tangentially and you'll be able to rotate the broken bolt.
I've extracted a number of broken bolts using this method.

I'd try the extractor route recommended above. Failing that drill trough and tap again