Selection of the sheared normal length for an involution gear wheel

Error of gear shape, gear distance, and gear thickness to a gear wheel, it is generally described to measure the teeth numbers of a gear wheel on the sheared normal length's errors. This article provides the principle between the measured teeth numbers of a gear wheel and its sheared normal length, and grinding gear's theory of a discal sand wheel. Furthermore, the article states the process of making a gear wheel in more details.