I think this is crazy. But I'd rather have someone with experience
of using a dremel tool explain whether this is safe or not.

A female freind wants to cut some dado's or grooves for a shelf.
For the sake of arguement assume the depth to be 3/8" x 3/4" wide.
Dremel tool. I assume she has the router base for it. The wood is
old pine. It's hard and very dense.

Is this safe to do. "Personally I think the bits just going to come
flying off the dremel, when it get's hot and snaps...

Any thoughts...

Pat