Abstract: A quick change spindle adaptor for a power driven spindle having an axial bore and a tool holder having a shank axially projected into the spindle. A sleeve is secured upon the spindle and an outer shell is rotatably mounted upon the sleeve and retained thereon and includes a nut. A conical recess within the inner bore surface at the forward end of the spindle defines an axial bearing and receives a centering cone on the tool holder for maintaining an axial self alignment of the tool holder and spindle. Spaced threaded segments upon the tool holder are threadedly engaged by the nut for axially anchoring the tool holder upon the spindle and for biasing the centering cone into engagement with the spindle bearing.