I have to cut a 3" copper pipe in a wall I've opened up on one side. The problem is, the pipe is against a stud and the opposite wall, which has sheetrock an tile on it. I got it cut partially with my sawsall, but cannot cut it thru. Any ideas? This is a small opening of about 12x18 square. Been looking for some sort of cable saw that would cut copper, but no luck. You help is greatly appreciated.