How to Extract Broken Bolts

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Once a bolt has become broken, removing it can be a trying experience. The difficulty of extracting a broken bolt can depend on how much it is stuck, and where it is broken. Assuming the bolt head has broken off, and part of the shaft is sticking out, there are different extraction methods. These range from simply trying to pull it out to drilling the shaft and using a bolt extractor.

Things You'll Need

  • Vise grips
  • Propane torch
  • Penetrating oil
  • Hammer
  • Nut
  • Washer
  • Wrench
  • File
  • Power drill
  • Dental pick
  • Bolt extractor

Pulling it Out

  • Place vise grips on the shaft of the bolt.

  • Use vise grips to turn the bolt until it comes out.

  • Try turning the bolt both ways. The back-and-forth action can help loosen the bolt.

Heating the Bolt

  • Heat the bolt with a propane torch. According to SecondChanceGarage.com, heat the shaft until it is a "dull red color.'' A minute is considered the normal time needed to heat an average-size bolt.

  • Permit the bolt to cool down to the point it can be touched with a finger.

  • Apply a penetrating oil such as Liquid Wrench around the bolt. Let oil soak in for as long as possible. The longer the oil seeps in, the better it will work. Also try applying the penetrating oil before you do anything else. It takes a long time for the oil to work. If you are in no rush to remove the bolt, start with the oil.

  • Use a hammer to tap the end of the shaft to help loosen it.

  • Turn out the bolt with vise grips.

Build a New Head

  • Weld a washer to the shaft of the bolt. Make sure the washer is the same size, or a little smaller, than the broken bolt. Welding the washer also helps transfer heat to the bolt.

  • Weld a nut to the washer. Make sure the nut is the same size of the head of the bolt, or slightly larger. Weld to the outside parts of the nut.

  • Place the wrench on the new bolt head, and remove the bolt.

Bolt Extractor

  • File the shaft of the bolt so it is flat.

  • Drill into the shaft of the bolt with a left-hand drill bit. These bits are arranged in a left-hand pattern. It's possible the drill bit will bind to the bolt, and unscrew the shaft with a left-hand bit. Drill into the center of the bolt shaft. Use a bit that's smaller than the diameter of the bolt shaft.

  • Keep drilling if the bit goes all the way through the bolt shaft. Use a larger bit, and drill again. Continue drilling with a bigger bit each time until only remnants remain of the shaft. Remove remnants of the shaft with a dental pick or other small, pointed object.

  • Hammer an EZ Out bit into the shaft until it wedges. This is if you don't have a left-handed drill bit. An EZ Out is a tool designed to remove bolts. The upper part of an EZ Out bit is a square shape.

  • Attach the wrench to EZ Out bit, and turn until bolt comes out.

  • Hammer the bit and try pulling out the bolt again, if it's still stuck.

Tips & Warnings

  • Avoid breaking the shaft of the bolt. Breaking the shaft will make it even more difficult to remove.
  • Don't overheat the bolt when using a propane torch. Do not break off the EZ Out bit.

References

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