I am planning to screw a long oak plank to a lathe and plaster wall but I need to find the exact postion of the studs. Just poking a drill bit in the wall shows me where there is some obstruction but that could be the lathe or stud. Equally I an told a stud finder will not differentiate between the wood of the lathe or the stud. The plaster is old and crumbling so dont want to bo too much poking around so is there any stud finder that could be used ?