One of my favourite YouTubers, Matt shows what's what. - Part 2 to follow. From the comments underneath: "There hasn't been that much crack in a bottom end since Whitney and Bobby B were in an airport."
Are the jaws of a three jaw chuck harder than a case hardened crank. So much harder that they can mark the crank ?
Here’s mine, a good still for anyone interested. Exactly the same break as one of his and clearly shows the cross drilled channels he was talking about.
Interesting that the main bearing is gone as well. Wonder if that had any bearing (sorry) on the failure?