Means for indicating the profile of a workpiece

Means suitable for indicating the profile of a workpiece comprising a probe, first and second drive means respectively adapted to drive said probe along first and second mutually perpendicular axes to follow the profile of said workpiece, control means associated with said probe and said first and second drive means, means for supporting said workpiece to be followed by said probe and means adapted to display the outputs of said first and second drive means as an indication of the profile of said workpiece, said control means being adapted such that said probe is normally driven by said first drive means along said first axis at a substantially constant rate and that said second drive means drives said probe along said second axis to alternately make and break contact with said workpiece, said control means being arranged such that if the distance traversed by the probe along said second axis after a making but before a breaking of contact, or after a breaking but before a succeeding making of contact of said probe with said workpiece exceeds a predetermined limit, said first drive means is slowed down or halted until the succeeding making or breaking of contact respectively occurs whereupon said first drive means is restored to said constant drive rate.