  The Orthoglide project aims at designing a new 3-axis machine tool for High
Speed Machining. Basis kinematics is a 3 degree-of-freedom translational
parallel mechanism. This basis was submitted to isotropic and manipulability
constraints that allowed the optmization of its kinematic architecture and legs
architecture. Thus, several leg morphologies are convenient for the chosen
mechanism. We explain the process that led us to the choice we made for the
Orthoglide. A static study is presented to show how singular configurations of
the legs can cause stiffness problems.
