This paper presents a new procedure by which standard machine elements can be reverse engineered. Standard elements or components need not be scanned and identified as surface or solid model. The standard character is sufficient to be identified by few parameters. These parameters can be measured or deduced by calculations from certain geometric relations. The procedure presented herein is devoted to the reverse engineering of spur and helical gears. Other standard machine elements can be treated the same way. A computer aided reverse engineering (CARE) program is used to satisfy all geometric constraints, identify other dependent geometries and define production and inspection requirements. It allows the further check of the design appropriateness of material selection and loading conditions.