This paper focuses on efficient algorithms for automatic recognition of user-defined turning features on mill/turn parts. As with other domains, recognition of interacting features is a difficult issue because feature interaction removes faces and alters the topology of the isolated turning features. This paper presents a method for efficiently recognizing both noninteracting and interacting rotational features from CAD model of mill/turn parts. Additionally, the method supports user-defined turning features that are represented using N-REP , a neutral feature representation language. First, the profiles of the revolved faces on a mill/turn part are obtained and the unturnable portions of these profiles are detected. These profiles then are used to construct the part graph and to solve feature interactions between coaxial turning features. Finally, graph-based and rule-based feature recognition are combined to recognize user-defined features.