= ball diameter
B = overall length
C = stem diameter
D = effective working length
Renishaw uses a standard description of overall length, measured
from the rear mounting face of the stylus to the centre of the ball.
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
A few simple rules for stylus selection can be applied to maximize
accuracy for most probing applications
The more the stylus bends or deflects, the lower the accuracy.
Probing with the minimum stylus length for your application is the
Every time you join styli and extensions, you introduce potential
bending and deflection points. Try, wherever possible, to keep to
the minimum number of pieces possible for your application.
There are several reasons for this:
it maximises your ball/stem clearance, thereby reducing the
chance of false triggers caused by 'shanking out' on the stylus
stem, and increasing the EWL;
a 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.
EWL can also be affected by assembly tolerances. For this reason
Renishaw styli are assembled to exacting standards in controlled