M3 RENISHAW, Styli straight, ruby sphere, ceramic shaft
Spherical styli have the largest field of application because they have the same probing behavior in every direction. They are therefore suitable for all common measuring tasks such as measuring bores and surfaces. The larger the stylus sphere size, the larger the mechanical filter. This means that the profile of your workpiece is smoothened, which is often required in form measurement. The deviation from the ideal sphere shape is usually shown in Grade. ZEISS styli spheres have Grade 5 as standard, but can also be offered in a higher quality for special requirements.
Ceramic shafts offer high stiffness with low weight and are therefore particularly recommended for long stylus shafts where weight and a high stiffness is a critical factor. The straight shaft is the simplest stylus design and the one with the longest usable length. The full shaft length can be used as measuring length. Ceramic shafts have a high rigidity, but are also very fragile. In thermal behavior and weight, they are worse than carbon fiber
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.