The tool addendum haP0* is defined from the datum line with the tooth thickness π∕2Pnd as follows:
Using the convert button the tool addendum haP0* can also be calculated from an addendum hat measured from a reference line with a different tooth thickness snt.
snt = normal tooth thickness of the tool at the tool line. This thickness is usually equal to π/2 (in terms of Pnd = 1.0) for gears that are not subsequently finished by shaving, grinding, skiving, etc. For gears that are finished by one of the above mentioned finishing methods, the tooth thickness of the rack-type cutting tool is sometimes made thinner than π/2 to provide stock allowance for finishing i.e.,
The tool addendum can also be calculated by a given root diameter using the convert button.