The tool used to cut the inner ring of a gasket is typically referred to as a "compass cutter" or "hook knife."
The defining feature of this type of tool is its ability to precisely cut a circle through a rotational motion, utilizing an adjustable metal pivot point to anchor the center. When working with leather or rubber gaskets, a "rotary cutter"-equipped with a rotating blade-may also be employed. However, if the gasket is made of metal, a more specialized "metal compass cutter" is required; these tools feature blades made of tungsten steel or ceramic materials to ensure superior hardness.
During the cutting process, it is crucial to maintain steady downward pressure and rotate the tool in a single direction at a uniform speed; failure to do so may result in the blade veering off course and damaging the material. For industrial-grade, thick gaskets, the cutting is often performed directly using a "round hole punch" on a CNC punching machine; however, for home-based crafting or manual applications, a compass cutter remains the more practical choice.
