Introduction

A flat sunk bolt with an Allan head was torn out, the hex key had no grip and the sunk bolt could not be grasped with pliers. It was a fat bolt so drilling out would have been very difficult.

Parts

No parts required.

Image 1/1: Place a screwdriver in the slot and tap with a hammer in the counter-clockwise sense to loosen the bolt.
  • Cut a slot into the screw head.

  • Place a screwdriver in the slot and tap with a hammer in the counter-clockwise sense to loosen the bolt.

  • Unscrew the bolt with the driver.

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Finish Line

24 other people completed this guide.

Wolfgang

Member since: 02/17/2012

337 Reputation

3 Guides authored

3 Comments

Use the same technique for Philips or crosshead screws.

Use a grinding / cutting disk, not a saw blade. Apply the rotating cutting disk gently, do not force or it will break.

If this is a toughened steel or stainless steel bolt (much tougher), it will be best to use a reinforced cutting disk.

Use a dusk mask to avoid breathing the dusk from the disk !

(No, I don't usually, but I should !)

Frank B - Reply

While this works it is very difficult to not ruin the material around the bolt.

What I do is use a torx bit. size one up that is slightly larger then the hole and then firmly tap it in. atttach your drive handle a turn slowly while pushing down. this will normally break it free.

Also before your get to this point try putting your allen key in the hole and smack it with a hammer. sometimes the force of the hit will cause the metal to "break" enough that the allen screw wont strip.

Jamie Mcguire -

There are also specifically designed screw extractors made for this. These tools are generally two-sided: one side is used to drill the hole, while the other is inserted to extract. If the process works, the surrounding area is undamaged.

Karl Kaufmann - Reply

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