I think the author of H+L*D is saying to you Hight + Length * diameter is what your looking for. However if your just cutting saddles for say 2" pipe or 1 1/4" pipe od. Just come off the ends about 3/8" of an inch and round it out. Make sure your side of the pipe on the high inside is smothed out a bit and it will fit over the pipe. I usually cut mine with a 4 1/2 angle grinder with an 0.45 than quick sand. They do make punch cutter that give you the same cut i disscribed with less effort involved and size the pipe for you already. You can get one for hydrolics or manuel. But if expense is the key, try just the cut off wheel and some light sanding.
