A contour follower includes a plurality of sensors spaced around a waterjet nozzle, each of the sensors being configured to measure a distance between a working surface and a first plane, perpendicular to a longitudinal axis of the nozzle. The magnetic attachment mechanism can be used to releasably attach at least two objects together in a preferred configuration without fasteners and without external intervention. Preferably the engagement prevents liquid from passing therebetween. Air resistance measurements, taken through the air snap gauge provide a measure of diameter of the journal while relative linear motion between the base and air snap gauge, measured by the second gauge, provides a measure of journal runout relative to the center axis of the camshaft. The visual representation of the second farm is associated with the second end of the visual representation of the secure connection. The bases lie at different depths from a reference level defining the interior wall of casing.