Styli – Rules & Tips

Your choice of stylus configuration can have a significant effect on the accuracy of   the measurements you take. A few simple rules can be applied to maximize accuracy for most   probing applications.

Terminology

Styli Dimensions

 A = ball diameter, B = overall length, C = stem diameter, D = effective working length

 Effective working length (EWL)

This is measured from the centre of the ball to the point at which the stem will foul against the feature when measuring ‘normal’ to the part

Keep styli short

The more the stylus bends or deflects, the lower the accuracy. Probing with the minimum stylus length for your application is the best option.

 Minimize joints

Each time you join styli and extensions, you introduce potential bending and deflection points. Wherever possible keep to the minimum number of pieces for the application.

 Keep the stylus ball as large as possible

Reasons for this are:

Maximizes your ball/stem clearance, thereby reducing the chance of false triggers caused by ‘shanking out’ on the stylus stem, and increasing the EWL;

Larger ball allows a larger stem diameter, increasing the stiffness of the stylus;

The larger ruby ball reduces the effect of the surface finish of the component being inspected.