Notching is a fabrication process where a specific profile is cut out of the tube, usually at the ends. In modern automated tube mills, this is often done using a 3D laser or a specialized mechanical punch. The most common type of notch in the industry is the "saddle notch" or "fish-mouth notch," which allows the end of one tube to fit perfectly flush against the side of another tube. This is essential for creating high-strength welded frames, such as those found in roll cages, motorcycle frames, and construction scaffolding. Precision notching ensures that the gap between the two tubes is minimal, which is a prerequisite for a high-quality, full-penetration weld.