Precision of shaft basing in centers

Analytical formulas for the errors of shaft basing in centers are presented. Recommendations for more precise basing are outlined. The bases and theoretical basing systems currently employed for shafts in centers were analyzed in [1]. In addition, the main factors affecting the basing precision for the executable dimensions were identified. In the present work, we consider the basing error when the two most common systems for blanks with conical center holes are employed: 1) with a rigidly fixed front center and a mobile rear center (Fig. 1a); 2) with a recessed front center and a mobile rear center (Fig. 1b). First we determine the basing error for the executable dimensions due to each factor separately and then we consider their combined action. In the calculations, we use the approach outlined in [2, 4].