Dimensional errors of the parts from a part family cause the initial misplacement of theworkpiece on the fixture affecting the final product quality. Even if the part ispositioned correctly, the external machining forces and clamping load cause the part todeviate from its position. This deviation depends on the external load and the fixturestiffness. In this article, a comprehensive analytical model of a 3-2-1 fixturing systemis proposed, consisting of a kinematic and a mechanical part. The kinematic modelrelocates the initially misplaced workpiece in the machine reference through the axialadvancements of six locators taking all the fixturing elements to be rigid. Therepositioned part then shifts again from the corrected position due to the deformation offixturing elements under clamping and machining forces. The mechanical model calculatesthis displacement of the part considering the locators and clamps to be elastic. The rigidcuboid baseplate, used to precisely relocate the workpiece, is also considered elastic atthe interface with the locators. Using small displacement hypothesis with zero friction atthe contact points, Lagrangian formulation enables us to calculate the rigid bodydisplacement of the workpiece, deformation of each locator, as well as the stiffnessmatrix and mechanical behavior of the fixturing system. This displacement of the workpieceis then finally compensated by the advancement of the six axial locators calculatedthrough the kinematic model.