Rounded out allan bolt removal?

What size is the hole in the head? Take the other one to the hardware store and ask if they have an easy out that will fit it. You may have to drill out the hole a little deeper for the easy out to get a good bite on it. While you're there you might as well ask if they have the replacement bolt.🙂

If you have a Dremel tool, sometimes you can dremel a slot into the bolt-head and then us a flat-tip screw driver to remove the bolt.

They're probably metric allen keys. You might also try to obtain a set of English allen keys, one might fit the rounded out hole a bit tighter. I got a rounded off metric allen bolt out once using an English allen key.

I got another recalcitrant allen bolt out by cutting a notch in the head of the bolt, laying a screwdriver on the notch at an angle, and hammering (gently) in the direction I wanted the bolt to turn. A few taps got it started, then it spun out easily.

OTOH, Magura hydraulic calipers aren't cheap. This might be a time to find a local LBS to handle it for you. It's a wise mechanic who knows when to back off and call in the pros.

Caher said:

Hi all,
..one of the bolts have become rounded.
Any ideas how i can get this bolt out?
Very grateful for any ideas.
Caher

Have you , or any of your friends access to an electric welder? (Preferably a MAG wire-feed, but stick will do in a pinch) Place a nut on top of the Allen, run a bead through the nut and into the Allen. Allow to cool, remove with socket wrench.