Abstract: A positioning and retaining plate assembly for the controlled location of a spectacle frame comprises three superposed plates slidably mounted in relation to each other. The upper plate, or tray, includes fastening means for a spectacle frame, and is slidable in one direction over the middle plate, or bed plate. The bed plate is slidable in a direction at right angles to the first direction over the lower plate, or base. Locking means are provided for locking the plates in position. The assembly may be mounted on a pedestal provided with a reflective upper surface on which reference axes are marked which can be viewed through apertures provided in the plates.

Abstract: A copying machine which can reproduce convex or concave surfaces having smaller radii of curvature at the edge than at the center, for example the surfaces of moulds for making contact lenses, has a cam assembly including a cam with a part-cylindrical cam surface mounted on a base. The cam has a part-circular section in the plane perpendicular to the cam surface generatrices and a straight section tangential to and continuous with one end of the part-circular section. The latter is slidably mounted on a concentric part-circular guide on the base, allowing rotary movement about its geometric center. The guide and at least the part-circular section of the cam have complementary square profiles. The part-circular cam section may be locked in position on the guide by screws threaded into the guide and passing through a concentric part-circular slot in the cam.

Abstract: The invention relates to a variable-profile cam of the kind comprising a cam-surface formed by one of the longitudinal faces of a thin strip extending freely between at least two supports, of which at least one is adjustable transversely in position, in which the thin strip is made of an elastically-deformable material, and the transverse moment of inertia of the strip can vary between the two supports, for example by variation of the width or the thickness of the strip. The invention is particularly applicable to cams for reproducing machines for the production of aspherical surfaces of moulds for contact lenses.