Removing damaged/corroded allen head fixings?

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mjr
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Removing damaged/corroded allen head fixings?

Postby mjr » 9 Sep 2019, 2:48pm

I found a few ideas on how to remove the infernal things in viewtopic.php?f=5&t=119708 but does anyone know a table of which common imperial size allen keys or Torx bits to try in which damaged/corroded metric sizes, please? I'm facing what I think is a rounded-off 2mm allen head grub screw (I think that's the name) on a friend's wheel hub axle and I'm trying not to make matters worse! :(

At least when those stupid heads corrode on things like Shimano-style brake pad holders, you can throw the holder away, fit a new one and use a stainless securing bolt in future, but I'd rather not advise throwing this axle away just because one stupid head corroded. Whatever genius thought of using them on axles deserves one putting up each nostril!
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
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Brucey
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Re: Removing damaged/corroded allen head fixings?

Postby Brucey » 9 Sep 2019, 4:26pm

2mm is very close to 5/64" so there isn't an imperial allen key that is close enough to be worth trying. Regarding torx bits, measure up and have at it; they vary in size from that specified and can be ground tapered/smaller so that they fit better; (the 'correct size' for this job is the one that needs tapping into the allen key socket with a small hammer).

FWIW if the screw is set in aluminium you can often get even a grub screw out (provided it isn't recessed) with a blob of weld metal.

If push comes to shove the screw can be drilled out, and new hole drilled and tapped for another screw. Needless to say the new screw should be fitted with more grease etc to delay a repeat performance...

cheers
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Manc33
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Re: Removing damaged/corroded allen head fixings?

Postby Manc33 » 10 Sep 2019, 1:44am

Are people/bike part manufactures gradually replacing allen bolts with Torx? I keep seeing more and more Torx heads on things. I remember back when you only got allen bolts on mid-high spec bikes and cheaper bikes had Phillips screws everywhere. Why don't they just make it an equilateral triangle and have done with it. :!:
Only weird bikes are interesting anymore.

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mjr
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Re: Removing damaged/corroded allen head fixings?

Postby mjr » 10 Sep 2019, 9:24am

Thanks for that. I got the screw out with an oversized allen key from a cheap bike toolkit! (2.05mm according to the calipers)

I still can't get the cap off because the dent made by the screw fouls it. I forsee a rubber hammer in this wheel's future...
MJR, mostly pedalling 3-speed roadsters. KL+West Norfolk BUG incl social easy rides http://www.klwnbug.co.uk
All the above is CC-By-SA and no other implied copyright license to Cycle magazine.

pwa
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Re: Removing damaged/corroded allen head fixings?

Postby pwa » 10 Sep 2019, 9:29am

For a rounded off allen head screw that has its head proud of the thing it's screwed into, I have had success with filing two parallel surfaces and using a tiny spanner. But you need to be able to get the file in, which often you can't.