Hollow mill tool

A hollow mill tool comprising a shank portion and a plurality of radially spaced and axially extending tool posts integrally formed with and projecting from said shank portion about a longitudinal axis of said tool, each of said tool posts having a longitudinal cutting insert mounting face, each mounting face defining a first plurality of axially extending serrations, a cutting insert mounted on each mounting face, each cutting insert having a cutting edge which defines a cutting cylinder upon rotation about said longitudinal axis, each cutting insert having a second plurality of axially extending serrations defining a back face and intermeshing with said first plurality of serrations, a threaded fastener extending through a front face of each said cutting insert and being received in each cutting insert mounting face of said tool posts to securely hold each cutting insert against its tool post,

• wherein each cutting insert has a trapezoidal transverse cross section,
• the back face and the front face of each cutting insert are parallel,
• the back face and the front face of said cutting insert are connected by first and second side faces, said side faces forming acute angles with said front face at a longitudinal intersection defining a cutting edge, and
• each cutting edge defines a line lying in a plane tangent to a cutting cylinder and wherein said cutting cylinder has a diameter corresponding to an outside diameter of a workpiece machined to a tolerance of ±0.001 inch by said mill tool.