Often when a bolt or stud breaks off, it breaks with a little bit protruding above the material it's threaded into. In this situation, it is sometimes possible to use a pair of vice grips or such, to facilitate the removal of the bolt. More times than not though, this won't work for the very reason that the bolt broke in the first place. A worse case scenario is when the fastener breaks flush or lower than flush with the workpiece. Worse again, is when it's a high tensile fastener that has broken off, lower than flush. Being high tensile, it will be difficult or impossible to drill and use an ezi-out or something similar. In all of these cases, there is one method that will nearly always remove the broken fastener. It utilizes the beautiful welding disipline of TIG. Please visit my link below to see this in action, and straight under the video, you will step by step stills and an explanation of each step.
Step 1: The Object With the Broken Bolt or Stud
So here we have an inlet manifold. It's made of an aluminium alloy of some type. It's not important what it's made of. It could of been cast iron, or anything else for that matter, and the following process would still work . In this example, the bolt has broken off leaving nothing protruding. If it had broken off, leaving a section of the bolt protruding above the manifold etc, we could of probably used vice-grips or something similar to remove the broken section of the bolt. In our case, it has broken off below the surface of the material. What's worse is that it's a high tensile bolt, so it would be hard to drill and use an ezi-out etc. We will be using a TIG welder to weld a bolt to the broken section, and remove the culprit using a spanner on the bolt.
Step 2: Showing the Broken Bolt and the Complete Bolt That We Plan to Weld to the Broken Section
In the first photo in this step, you can see the end of the broken bolt that we are going to build up using the Tig welder. In the second photo, I am pointing to the end of the broken stud, with the actual mild steel filler rod that we are going to build it up with. The final photo in this step shows the bolt that we are going to TIG weld to the built up broken bolt.
Step 3: Building Up the End of the Broken Stud With the TIG Welder and Metal Filler Rod
Step 4: Preparing the Bolt That Is to Be Welded to the Mound on the Extractee
It's a good idea to grind off the zinc, if you're using a galvanized or zinc plated bolt. Not only will it make it easier to TIG weld, but it will avoids the zinc fumes that would otherwise arrise. Zinc vapour is bad for humans.
Step 5: Clamping the Bolt in Position Whilst We Get a Tack Weld Onto It
Here we are clamping the bolt into position, with a pair of vice-grips, so that we can get a tack weld onto it before we remove the vice-grips. Note the nice improvation of using the hole-saw as a spacer. Any handy spacer (that doesn't burn), would of done.
Step 6: Tack Welding the Bolt Onto the Built Up Mound
Step 7: Completing the TIG Weld, Now That the Vice Grips Have Been Removed
Again, the title of this step is fairly explanatory. The vice grips have been removed and we put a weld 180 degees from the tack weld, and let it cool for a few seconds. (I know I refer to the first weld as a tack weld, but I didn't even bother rewelding the first weld, as TIG welding is enormously strong and beautiful)
Step 8: Removing the Broken Bolt With a Spanner on the Welded on Bolt
Finally, we simply use a spanner, and the broken section of bolt comes out quite painlessly