M3 XXT, Star styli straight, ruby sphere, stainless steel shaft
Star styli consist of spherical styli combined in a star shape and enable measurements in different coordinate directions. Where as probing with spherical styli from the side surfaces is only possible to a limited extent, with the star stylus you can select the stylus for probing that is orthogonal to the probed surface.
Stainless steel shafts are used where special diameter or connections are required. Most of them are used for custom-made devices. They are easy to machine and thus more favorable for special fabrications. Compared to tungsten carbide, however, the bending behavior is considerably worse. Therefore, large diameters are preferred for stainless steel shafts
Ruby styli are the standard for almost all applications and are available in a variety of different diameters. Another advantage is that ruby spheres can be produced in very small diameters (from 0.12 mm). On the other hand, ruby has weaknesses at the continuous scanning of certain materials and surfaces. With extremely soft materials, e.g. aluminum, material from the workpiece can be deposited on the ruby surface (material deposit). Very hard and rough surfaces, e.g. castings, on the other hand, cause abrasion of the sphere (material removal). The shape of the sphere changes as a result and loses accuracy.