Abstract: A rethreader tool for use in a internally threaded hole of which the internal thread pattern is in need of repair. The assembly providing a expandable, collapsible and reusable device for achieving the purposes of the internal thread repair. In the collapsed state the rethreader finger section of the base can be inserted into the damaged thread pattern of the hole without making contact with undamaged internal threads therein. The application of mechanical means expands to the rethreader finger section to the exact diameter of the hole. During the expansion process the internal thread pattern of the hole and threading pattern of the rethreader finger section seat together. Rotation of the expanded rethreader finger section in the hole repairs the internal thread pattern of the hole to its original specified pattern. After completion of the rethreading process the rethreader finger section is collapsed by mechanical means and withdrawn from the internally threaded hole.