"professorpaul" wrote in message
oups.com...
There is also a tool called a "grout saw," especially for this
purpose. Has little bits of what look like Carborundum or tungsten
carbide on the edge, with a small handle. If you slip with the Dremel
tool, you can easily damage the tile. The grout saw is pretty quick.
Any "big box" store, or a tile supply house. Forgot where I picked
mine up.

Yeah, but that drill bit would work on larger grout lines.

Homedepot has a grout saw where you can replace the blade when it wears out.