Can anyone tell me the cutting depth on 115/125/230 grinders.. on average? I need to cut a channel down two walls behind where the skirting used to be to redirect/hide c/h pipes. One wall is brick, the other concrete. Wall chasers dont look like they'd get near enough to the ground for the job. Will a diamond blade go through steel too or will i just have to go slow and swop blades when i find rebar?