Step 3 · Support the Pipe
Before cutting, you must support the heavy cast iron pipe to prevent it from dropping or pinching the saw blade. Place secure supports on both sides of the section you intend to cut out. You can use plumber's metal strap secured to overhead joists, or build temporary supports using wood blocks (2x4s). The supports must be snug against the pipe and capable of bearing its full weight. This step is critical for safety and for preventing damage to the remaining plumbing.