A stylus is the part of the measuring system that touches the component. Maximum rigidity and a spherical tip are the two variables that decide the result.
| Stem material | Best for | Notes |
|---|---|---|
| Stainless steel | General purpose, 10–50 mm | Good balance of stiffness and cost |
| Tungsten carbide | Balls ≤1 mm, lengths ≤50 mm | Maximum stiffness in small diameters |
| Ceramic | Balls >3 mm, lengths >30 mm | Lighter than carbide; shatters on crash |
| Carbon fibre (Renishaw GF) | Lengths >50 mm | Low mass, high stiffness, thermally stable |
Standard Renishaw ball sphericity. AFBMA 3290 / DIN 5401 Grade 5 minimum.
Undrilled ball bonded into a spherical cup; titanium-nitride-coated stem for identification.
Ruby, silicon nitride, zirconia and tungsten carbide, depending on the application.