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Sheared Bolt
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Post Sheared Bolt 
Guys, need your input. I have a bolt (M12 by 1.5) that was sheared off by an impact with a curb. The bolt holds the engine mount and was torqued to between 35 to 50 lb-ft I believe.

The bolt is broken flush with the frame member it was bolted into - and also bent backwards to a few degrees at the point of shear.

I attempted to use an extractor but that has failed so far. One extractor broke inside the drilled out bolt and I had to drill for hours to get that back out. Then I used a stepped bit rated for this use and made some good progress, but the end of the stepped bit broke inside the hole in the bolt and now I'm having to drill the broken part of the stepped bit out.

I have looked at many options - spark eroder, plasma cutter, etc. But, the bolt location is on the bottom and puts me upside down under the part and it doesn't look like a lot of the options will work upside down.

Here are some links:

http://mikesworkshop.weebly.com/a-spark-erosion-apparatus.html

http://www.homemadetools.net/homemade-spark-erosion-apparatus-mk-3

http://www.homemodelenginemachinist.com/downloads/files/Easy_Spark_Eroder.pdf

https://www.rcgroups.com/forums/showthread.php?1209516-spark-eroder-plans

https://www.youtube.com/watch?v=Hxtg2nAIYw4

Any ideas?

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Can you get in there and weld another bolt to the sheared off part? If so you might be able to soak the part with penetrating oil, heat up the part with a torch and back the bolt out. Good luck.

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I can't get to the bolt to weld to it because it is flush with the frame - might end up welding it in place.

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I finally got it out. Took a ridiculous amount of time because of the failed extraction and broken step bit. I will post pictures later of the process.

There has to be a better way to remove broken bolts - this was a crazy amount of time and I don't see how a shop would be able to allot this amount of time to a broken bolt removal. Maybe they would have just cut that section of the frame out and welded in a new piece?

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