Marty,
Went back back to your original post on this thread before the conversation turned toward the benefits of the CBN wheel as versus an AO or other stone wheel. There is no argument about the benefits of a CBN wheel but alone they will not prevent "mishaps" as proven by Russ. So may I ask how your tool and jig "slammed" into the wheel. Were you grinding too close to vertical center or did the jig come loose and allow the tool to go below center. Did you get the tool between the inside of the wheel and the grinder? Please be a bit more specific.
faust