Look at the Fein Multimaster. They have carbide and diamond blades
specifically for grout removal.

Boden

Rob Houston wrote:

I need to re-grout a bathroom ceramic tile floor with badly discolored
grout. The grout line width is 1/4 inch. What is the easiest (and best)
way to remove at least 1/16 - 1/8 depth of the old grout? Is there a power
tool that won't damage the tile?

Thanks, in advance, for your help!

Rob Houston