12.11 Tool addendum

The tool addendum haP0* is defined from the datum line with the tooth thickness π∕2Pnd as follows:


Figure 12.5: This figure shows a normal plane view of a rack-type generating tool (hob, rack cutter or generating grinding wheel).

Using the convert button PIC the tool addendum haP0* can also be calculated from an addendum hat measured from a reference line with a different tooth thickness snt.


Figure 12.6: AGMA 2001/2101 - Addendum of tool


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.,

 snt  =   π∕2 - 2 ⋅ us
haP0  =   addendum  of tool measured  from  the tool datum line.

ρaP0  =   tip radius of tool.
  δ0  =   protuberance of tool.

The tool addendum can also be calculated by a given root diameter using the convert button.