Rounded top-cup bolt

[Lightweenie]

Hello, unfortunately I have rounded my top-cap screw while assembling it. I didn't think an aluminum bolt would be THAT soft. I do not need to remove it urgently, but at somepoint I will so I better take care of this earlier. I tried the method where one fits in a hex screwdriver and removes it, but I only ended up rounding the bolt even more. Here is a picture:



Any ideas? I was thinking that if i could somehow cut in a line in order to use a flat-head screwdriver, or even better a cross and use a phillips screwdriver, it should work, but I am not sure how to do the cutting in part.

[Cleaner]

I would try a screw extractor first which should work easily on a low torque aluminum bolt. You may have to drill a pilot hole for the extractor.

If that fails or you cant get an extractor then try using a drill bit to remove the top of the bolt from the shaft.

If you drill a hole in the center of the bolt using the appropriate size bit the head should separate from the shaft of the bolt. You can then remove the threaded shaft as you will have access by unscrewing it by hand.

[BRM]

You rounded it most likely because you have hex with a poor fit. (I asume this because I see these things a lot)
Cases like this are the perfect example that quality tools are essential and worth to give out some extra money. On the long term they pay out. If you would have had a good tool you would not have ruined your bolthead and more important you would not have had all the hassles to correct it.

[fh8425]

or alternatively you can try a slightly over size star bit and gently hammer the bit into the rounded bolt head, ensure it does fit snuggly before you attempt unscrew the bolt ...

[Lightweenie]

@BRM: I know that I messed it up and writing just to tell me this, is not really constructive nor helping me to solve the issue. For your information, my hex keys are really high quality. In my first post where I said I tried the method of inserting a hex, I meant to say torx (which is also good quality, or at least high price). As I see it the reason I messed this up is that I was used to my previous headset, where the top cap and the expander were one and the same and connected with a steel bolt. The new one is different, has an aluminum screw and once I put very slight pressure on it (which I shouldn't have), it started rounding. I should have thought this through before and not do it on "auto-pilot".

@all: thanks for the ideas so far. While searching around the internet, I found another idea: remove the handlebars, loosen the stem bolts and try holding the wheel between the legs and turn the stem around counter-clocwise. May try this first tonight before trying anything else.

[jekyll man]

Don't do that!!

All you risk doing is creating a highly stressed area on your fork (esp if it has a carbon steerer).

If you have a carbon spacer under either the top cap, or beneath the stem, see if you can split it using a sharp chisel or screwdriver. This will allow the cap to drop the depth of the spacer, and you can get some pliers (or mole grips if its frozen in) on the bolt head.
Another option is to drill 2 holes in the top cap, and use snipe nose pliers to turn the cap and hope the bolt unscrews with it..

BRM is always condescending, but he's right; decent tools (along with some basic maintainance knowhow) help prevent stuff like this happening

edit: the torq bit approach often works but i'm not sure if the bolt being Alu would be too soft for it to bite into.

[Attermann]

tap on a screwdriver or drill out the head, the thread should be easy to remove with pliers after

[BRM]

Dont take it too personal . . .
What has overcome you is not fun and can't be avoided all times but many of these situations are not necessary.

Someone else before me mentioned already an extractor. Its really all you need. I saw no reason to repeat that info but I saw reason to warn others. I wrote this because there is a stubborn group of people that think that budget tools are good enough for them, they can't imagine what can go wrong. Even when you tell they dont believe and cant be bothered, till something like this suddenly happens. What happened to you is what happens a lot with budget tools with a poor fit. A good example of mess you don't want it overcomes you. So thats the warning. Constructive advice for all that read.

Avoid all unnecessary stress/hammering that can cause other damage.
Stop searching to other methods and buy an extractor in your local DIY / Toolshop or online.

Hope you solve it soon, cant be too difficult.

[McGilli]

What always works for me is a Dremel. Using a cutting disc I very lightly cut into the hole - making two notches on the sides. Then with just a wide flat head screwdriver ta da it's out.

If you're saying "but the bolt is flush with the top cap and the disc will cut the top cap" then what you do is use the cutting disc on a piece of scrap metal first - to wear it down - decreasing its diameter. So - you can make the cutting disc the width of just the bolt or a touch smaller - and then no worry you will never hit the top cap

PS - lots of caffeine before doing this not recommended - you want steady hands