Patent ID: 7440814

Claim:
A method for auto-calibration of at least one tool in a single point turning machine used for manufacturing in particular ophthalmic lenses, wherein a cutting edge is formed on said tool which has a three-dimensional shape and position relative to width, length and height directions of said machine, said method comprising the steps of: (i) cutting with said tool a test piece of rotationally symmetrical geometry about an axis of work rotation (B) requiring both positive and negative tool contact angles (θ) with said cutting edge; (ii) probing the cut geometry of said test piece at points which required positive and negative tool contact angles (θ) to obtain probe data, and storing said probe data; (iii) analyzing said probe data in respect of deviations of the cut geometry from the geometry which should have been cut in the width and length directions to obtain width errors and length errors, and storing said errors; and (iv) automatically controlling said machine to correct for said width errors and length errors.