How do you remove an Allen screw when the thread has gone...?

Fender76

From a stem, the Allen key cant get any purchase cos the thread has worn away... Any ideas..?

Prenderb

Fender76 wrote: »

From a stem, the Allen key cant get any purchase cos the thread has worn away... Any ideas..?

Try stretching a rubber band over the head of the screw then using the allen key (with the rubber band still in place...). The rubber might get you a grip.

Presume that there's no "external" access to the fastener, i.e. you couldn't get a vice grips to it?

Mech1

I assume you mean that the hexagon hole has rounded out?

Plyers/vicegrip & WD40?

Recon

You can buy a bolt removal tool, which is basically a drill bit with a reverse screw on the end of it that drills into the damaged bolt/screw and screws it out. I've used them a few times and they worked everytime.

Fender76

Mech1 wrote: »

I assume you mean that the hexagon hole has rounded out?

Exactly....

alphabeat

only way if the hex is worn is to drill it with gradually increarsing bit diameters until it falls away / collapses
then put a new one in.

or reverse drive the drill once drilled in

else bang a flathead screwdriver intothe hole with a hammer and try turning it .

either way the hex screw is toast

Rovi

The bolt with the rounded out Allen head is now effectively scrap, so you're looking to salvage things without damaging anything else at this stage.
A couple of options come to mind straight away:
Hammer in a slightly oversized Torx bit and see if that gives enough grip;
Drill off the head and remove the component, then extract the exposed stub with a Vise-Grips or similar tool.

Fender76

alphabeat wrote: »

else bang a flathead screwdriver intothe hole with a hammer and try turning it

That solution sounds most promising...

GoodisonPark

Cut a slot across the head with a junior hacksaw and screw it out with a flat head screwdriver.

Hungrycol

alphabeat wrote: »

else bang a flathead screwdriver intothe hole with a hammer and try turning it .

Try this first.

I've rounded a stem bolt on my stem cos I forgot its only about 6n of torque and I have it 12n! So, so as I don't need to move the bars anytime soon I should be ok!!

Mech1

if so, first put a lot of penatrating oil anyway you can around the bolt, even upturn the bike and check if there is a suitable hole to get oil to threaded part of bolt.

Then put a flat tipped punch or your allen key in the worn bolt head and give it a couple of sharp strikes of a hammer to help loosen bolt grip.

Find a Torx type bit that is just / only too large to fit in bolt head and hammer it into bolt head, it will cut your rounded allen key hole into a torx type hole. Do not remove hammered in torx bit before trying to turn it, bolt should loosen.

tippgod

alphabeat wrote: »

only way if the hex is worn is to drill it with gradually increarsing bit diameters until it falls away / collapses
then put a new one in.

or reverse drive the drill once drilled in

else bang a flathead screwdriver intothe hole with a hammer and try turning it .

either way the hex screw is toast

I second the flat head screwdriver. Have done it a few times and always worked. Don't worry about the star nut inside as they are cheap and easily replaced if it gets pushed down

kumate_champ07

use a cheap allen key and some quick setting epoxy resin, leave till its finished hardening and then remove easilt

BlackBlade

some funny and desperate attempts there pmsl...
only solution to this is to get a torque or spline bit thats close in size and tap it in with a hammer then just screw it out as normal!
no other method other than the messy job of drilling will work!

RacoonQueen

Had a similar problem last night. Eventually found a pliers to nab it with.

Columbia

Chill the entire bike to -250 degrees celcius*, hopefully the bolt will contract more than its surroundings and simply slip out.

*you may need to adjust your gears after this.

You're welcome

Fender76

Thanks everyone, gonna give the Hex bit a go, sounds the easiest..!