An adjustable cartridge to be mounted in a boring bar (10), the cartridge Including an anvil (24,28) rotatably affixed to said boring bar, said anvil including a pocket into which a laydown indexable insert (32) is affixed. The anvil is secured in an axially oriented slot (27) which includes an arcuate seating face (26). Means (46,47,51) for adjusting said cartridge in said boring bar along said adjustment path; and means (17,60) for preloading said anvil in said slot towards said adjustment means, are also provided, wherein said preloading means comprises a screw (58) which is threadably retained in said body proximally to said anvil and a leaf spring (60) which is retained in place by the screw and engages said anvil on a second recessed area (42) of said anvil.
Rotation of the anvil within the slot effects radial adjustment of the insert.