Uh Oh. Snapped Off A Hex Key In A Bolt Head.

[Lovacott]

If the action of the drilling doesn't shift it then you will need to resort to an extractor of some kind

I don't have a 1mm HSS bit but I can borrow one from work.

The problem is though, that to loosen the broken key, I'd need to apply an anti clockwise force rather than the clockwise force a drill would place on it.

The more I think about it, the harder it becomes.

 

[Pale Rider]

The fixing is not tight.

A drill/driver in reverse might spin it out.

 

[Lookrider]

If you have any tiny gaps in between the bolt recess and the edges of the snapped hex
Try tap in a sharp bradawl ( if available) tap in the 2nd bradawl
You can then use any form of suitable bar/tube/screwdriver/flatbar inbeween both bradawl to turn the bolt out
If you do not have any bradawl then any form of fine sharp pins or nails will do ....improvise somewhat

 

[Illaveago]

How much is a replacement part?
Could the cable be cut so that the mechanism can be taken off and worked on in a vice ?
I was wondering if the screw itself could be extracted by using a small punch to tap the edge of the screw to loosen it to extract it ? It might be an easier option provided you could get a replacement screw .

 

[Oldhippy]

Unlikely, but have you tried turning bike upside down and tapping the mechanics to see if it falls out?

 

[Lovacott]

A drill/driver in reverse might spin it out.

I've chewed over that one as well, but drill bits are designed to cut clockwise and glide counter clockwise. I'm not sure if it would work?

Of all of the issues I've ever faced in my life, this is without a doubt, the most minor. That said, I seem to be putting a lot more time and effort into solving it than I have ever put into some of my most major life decisions (which one to marry etc).

I greatly appreciate the effort of others who've proffered up their thoughts on the subject.

 

[Drago]

Hammer, chisel, deep breath, sorted.

 

[Gunk]

Bite the bullet and just buy a replacement front mech, it’s not the end of the world

 

[Electric_Andy]

IME the hardest part of drilling a small pilot hole for a screw or extractor bit is starting it off. Best getting a centre punch in it first, then I'd try screwing in a self tapper, it might only need a wiggle back to come out

 

[Gunk]

IME the hardest part of drilling a small pilot hole for a screw or extractor bit is starting it off. Best getting a centre punch in it first, then I'd try screwing in a self tapper, it might only need a wiggle back to come out

To drill that out with a hand drill is going to be almost impossible, that needs be clamped and drilled out using a pillar drill. As I said earlier, it’s not a stupidly expensive part to replace, it would easier to just replace it with a good used part.

 

[Once a Wheeler]

Supported in situ with plastic-covered gardening tie-wire, stick the snapped off hex key to the stub with Araldite and leave it to set hard. Fill a small plastic bag with ice and support it round the hex key. After a few minutes, gently warm the bolt head with a hairdryer and gently pull on the hex key to remove the broken-off portion.

 

[Pale Rider]

but drill bits are designed to cut clockwise and glide counter clockwise. I'm not sure if it would work?

Me neither, but you've nothing to lose by giving it a whirl.

You may not even need a drill, a small cross head or flat screwdriver bit might do the job.

 

[Drago]

Pilot hole, drill extractor bit, pat self on back smugly.

 

[fossyant]

TNT and hit it with a hammer. Should be fine.

 

[Lovacott]

To drill that out with a hand drill is going to be almost impossible, that needs be clamped and drilled out using a pillar drill. As I said earlier, it’s not a stupidly expensive part to replace, it would easier to just replace it with a good used part.

As it is, the cable tension adjustment is perfect so I could continue using the mech for quite a while yet.

Also, it's quite possible that I could manually set the cable tension close enough, simply by pulling the cable though and clamping it up.

One of the blokes at work is bringing in a Neodymium magnet tomorrow which may well fix the issue quite simply.

A new mech would be a last resort but it wouldn't be the end of the world.