I am wondering if there is a rule of thumb about how large a hole in a copper pipe you can braze over is. Sometimes a piece of pipe can be in a place that is tough to get cutters around or unsweating a joint then brazing back in is preferably avoidable like on a reversing valve. Is there some kind of guideline to let you know when the extra work is necessary? Like a 1/8 inch hole in a 3/4 pipe? Do the materials involved make a difference (soft/hard copper, 15/40% silver)?