Abstract: Apparatus for tracing the perimeter shape of the lens holding aperture of an eyeglass frame, or an eyeglass lens, includes a holder to releasably hold an eyeglass frame or lens for tracing measurement. A tracing stylus has a 3 axis movement control apparatus to move the stylus around an axis of rotation and in a vertical and a horizontal direction of a plane rotatable about the axis of rotation. The stylus is urged into horizontal contact with the frame or lens to be traced by a horizontal axis motor dynamically controlled to optimize the contact force between the tracing stylus and frame or lens during the trace process. Control of the vertical movement axis of the stylus optimally provides a weightless behaviour of the stylus permitting it to move vertically responsive to external vertical forces.

Abstract: A patternless edger apparatus is described which is mountable on mechanical pattern ophthalmic lens grinders. The apparatus has a mounting yoke adapted for mounting the apparatus in the place of the mechanical patterns to control the edge grinding of a lens blank. The mounting yoke includes a rotative spindle mount to interlock with the grinder pattern chuck and a mounting shaft releasably receivable in the spring clip bore of such lens grinders. A stored lens pattern and signalling from a grinder spindle rotational angle transducer are acted on by a microprocessor to control a motorized cam operative on the grinder pattern reaction surface to control the grinder to grind a lens blank to a perimeter shape corresponding to the stored lens pattern.