A: It seems to me that burs chatter when cutting all the way around, in a position similar to a drill bit cutting straight down. If a bur is cutting into a larger seat, it’s only cutting along a portion of its perimeter, and doing this, it is much less likely to chatter.

The other thing about chattering burs. though, is that a seat cut with one is a mess, not a smooth nice cut at all. Stones sitting in that sort of seat don’t fit well, even if it’s as close to the right size as possible.

Oh, and one other thing about chattering burs. Put a sweater on the poor thing to keep it warm, give it some hot chocolate to drink, and between the two, it’ll warm up enough to stop chattering with a bit of luck and luv…