Feeler for workpieces being machined

A process for detecting accidentally unexpected accidental perturbation acting on a feeler of a workpiece measuring device,

• said workpiece measuring device comprising:
• at least one feeler for the workpiece, each said at least one feeler comprising a rocking arm and a measuring head,
• wherein said rocking arm comprises a rod connected to the measuring head and comprises an adjustable contact pin element adapted to feel said workpiece, and
• wherein said measuring head is adapted to carry out measurements on the workpiece and comprises a first sensor adapted to measure the position of said rocking arm and adapted to produce a first measuring signal based on the position or displacement of the contact element, and at least one additional sensor, being a piezoelectric sensor, operatively positioned separate from the contact element, adapted to produce an additional measuring signal as a function of external perturbation acting on the feeler,
• a measuring apparatus in data connection with the feelers for receiving and analyzing the first measuring signal and the additional measuring signal for detecting sizes based on displacements of the feeler,
• said process comprising:
• calibrating position of said feeler as a function of the size by contacting said feeler with a certified sample, removing the certified sample from contact with the feeler;
• after said calibration, said additional sensor detects said unexpected accidental external perturbations consisting of unexpected accidental impulsive forces acting on said at least one feeler when the workpiece is not loaded on the measuring device, and the additional sensor perceives the unexpected accidental external perturbations and reports the unexpected accidental external perturbations by sending the additional signal to the measuring apparatus.