A method for positioning a rotary part on a machining fixture adapted to hold the rotary part for a machining operation is described. The machining fixture has a center axis and a diaphragm with engaging segments affixed thereto and extending away therefrom. The method includes mounting the rotary part on the machining fixture concentrically about the center axis and adjacent to the engaging segments, and then applying an axial force in a direction substantially parallel to the center axis against the diaphragm. This elastically deforms the diaphragm and radially displaces the contact members of the engaging segments into frictional engagement with a circumferential surface of the rotary part.

A method for positioning a rotary part on a machining fixture adapted to hold the rotary part for a machining operation is described. The machining fixture has a center axis and a diaphragm with engaging segments affixed thereto and extending away therefrom. The method includes mounting the rotary part on the machining fixture concentrically about the center axis and adjacent to the engaging segments, and then applying an axial force in a direction substantially parallel to the center axis against the diaphragm. This elastically deforms the diaphragm and radially displaces the contact members of the engaging segments into frictional engagement with a circumferential surface of the rotary part.

A positioning assembly for positioning a rotary part to be machined includes a machining fixture and a positioning device having an elastically-deformable diaphragm concentrically mounted to the fixture and defining an annular loading zone which receives an axial force substantially parallel with a center axis of the fixture. The positioning device has circumferentially-spaced engaging segments, fixed to the diaphragm and extending away therefrom, which have contact members that are displaced radially to frictionally engage the rotary part when the axial force is applied to the loading zone of the diaphragm.