The present invention has for its object, an internal micrometer comprising a cylindrical body, a control shaft which is movable in a rotational and longitudinal manner within the body and two conical coaxial members connected to one another by a rod, driven by said shaft and controlling the movements of at least one measuring key movable perpendicularly to the shaft of said conical members.
A bore gauge for measuring the internal diameter of tubes comprises at least two concentrically and rotatably arranged members connected by a helically wound spring member. The spring member is capable of contacting the inside surface of the tube and causing relative rotation of the members thereby indicating the internal diameter of the tube.
