In the past couple of years, techniques using 3D frame fields have emerged to design hexahedral meshes[1,2]. Those methods are based on a two-step process where a 3D frame field is built by assigning a frame to each cell of a tetrahedral mesh, then a parametrization algorithm is applied to generate a hexahedral mesh. In this paper, we propose a novel algorithm to generate block-structured hexahedral meshes for any CAD domain Ω. This work differs from previous ones in several points: (1) the proposed approach does not start from a pre-meshed boundary; (2) The frame field initialization does not put singularity lines around the medial object of Ω; (3) Frames are assigned to the vertices and not to the cells of the tetrahedral mesh; (4) We do not perform a parametrization process but we generate a block structure that partition Ω in meshable regions.