Geometric interference can occur in cylindrical worm gear set that makes use of oversized hob to cut the worm gear. In particular, the interference occurs easily in the design with high lead and low pressure angles. The interference results in a corner contact. In this study, we examined the influence of the machine tool setting errors of the worm gear hobbing and the influence of the shaft misalignments of the worm gear set on the interference. To determine the interference, we used the surface separation topology based on differential geometry. In addition, we also examined the hob oversize range required to avoid the interference under the condition of the machine tool setting errors and shaft misalignments. This study found that the interference can be avoided not only when the hob oversize is larger than the upper limit, but also when the hob oversize is smaller than the lower limit. This study also found that the interference can be avoided by applying the intended errors on the machine tool setting and shaft alignment, without manipulating the hob oversize.