The task of the mixed pure CAD generating method developed by the authors consists in finding only the points situated on the gear tooth surface. The use of the mixed CAD gear generating method results in a very large and particular type of Points Cloud: This contains points situated both in the tooth space, and on the tooth surface. The existing filtering programs and methods, as it was presented in previous papers, cannot deal with these particular point sets. The development of the named particular generating method claims an algorithm and a computer software which can find the envelope of the Points Cloud. This papers presents an Alpha Shape algorithm based filtering algorithm, adapted and developed to be used together with the mixed CAD generating software.