How hard can it be ? Epilogue! [RAW VIDEO]

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I've had good success with cobalt alloyed HSS drills in quite hard stuff and the benefit is that it's a bit more ductile than carbide, for those irregular/freehand/hokey-pokey jobs - the carbide really shines in highly controlled CNC applications

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With the part clamped in the mill vise, both carbide twist drills (the 11/32 drill for an attempt at direct-tapping the M10x1.25 thread, and the 13/32 drill for the Recoil insert) both dug through whatever was in there with no issues. For freehand work, I can see how cobalt would be more forgiving - and those carbide bits are not cheap! The weird part was that it wasn't just the bolt in the casting that was hard, that part of the casting was hard too. So it got cherry red and then was quenched while on the car? Or maybe a former owner took it off the car in an attempt to extract the broken bolt, hit it with a torch, and inadvertently hardened it? In any case, it's fixed now.

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@@FNR mechanical engineering forensics are fun if it isn't your own broken off stuff haha