The standard way to fix this is with a screw extractor. You drill a hole into the broken-off screw, twist in the extractor, and twist out the screw at the same time. It's a little tricky to do, especially for small screws, so it might be best to take it to someone who is experienced at this.
Another option is to drill out the screw and re-tap at the next larger size; a third is to drill it out and install a threaded insert. But I think you probably want the first option.
Also worthwhile to keep a few of the most common sized taps around, if only for cleaning out screw holes. They're not expensive.
Steve Maas Long Beach, California
Bob Hanson wrote:
> My friend got his newly repainted bike shipped back to him this week.
> Today he attempted to fit mudguards onto it. Three screws went in snug,
> but okay. However, the last snapped off inside the front fork eyelet.
>
> I saw the bike today. The screw had snapped off flush with the eyelet,
> after almost reaching through to the other side. He said it was going
> in tighter than the rest, but he just kept turning it harder, figuring
> it would simply "clean out" any excess fresh paint that may have built
> up in the threads.
>
> Before either he or I try to come up with a "solution"... Could someone
> PLEASE advise me on the best way to remove the broken screw. He just
> had the bike painted, so he definitely does not want to mess up the
> frame. He also wants to keep the threads from being damaged.
>
> This is something I've never encountered before so I really would not
> know how to proceed. I assume the screws are a standard 5mm metric,
> however, I don't recognize the fork tips - they're definitely not Campy.
>
> In fact, this raises another question. The frameset is British (Sorry,
> can't remember the name and decals were not re-applied). So, could there
> have once been a very similar sized, but perhaps Whitworth or BSC thread
> rather than metric, used to tap the eyelets? Maybe a "close but not
> quite the same" thread would account for the metric screws really
> fitting too tightly... or rather, perhaps not a suitable fit at all.
>
> I would greatly appreciate ANY advice. I know he's going nuts over
> this. I am pretty steady handed with a drill, but would not even know
> how to proceed to try to extract the screw. I would like to at least
> give him some responsible advice - before he simply jumps in and does
> the absolute wrong thing.
>
> Thanks much.
>
> Bob Hanson, Albuquerque, New Mexico, USA
>
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