The material of the auxiliary knife is T12A high-carbon tool steel, and the hardness after quenching is RC60~65. For the purpose of saving, medium carbon steel can be used as the knife body, and a section of high carbon steel cutter head can be welded in front.
There are also scrapers made of high-speed steel, this kind of secondary knife has good wear resistance, but the sharpening is more difficult, and the knife edge is not easy to grind, so it is rarely used in general.
In some cases, due to material limitations, waste saw blades on the sawing machine, or thin disc milling inserts can be used as cutter heads, welded on the cutter body to make secondary cutters. It is also possible to make scrapers from old files. Files have teeth and are prone to cracks during the forging process. Therefore, the file should be smoothed before forging to prevent cracks. Or directly annealed with a file, planed or sharpened to the desired size. Forging scrapers from ready-made materials should also be careful not to produce cracks, and cracked scrapers cannot be used.
