As i post a little while back, i have some inside and outside corners in our shower that have cracked. Well, i got around to starting the grout removal with my sonicrafter. I used a carbide grit blade advertised for grout removal. It chewed that thing up pretty quickly. I can't keep going through these blades so i'm gonna look for a diamond grit blade. Is that the way to go? Or, if i have to, call in a pro to do the job. Many project to do and little time.