The study deals with the compensation of gravity loads in closed-loop mechanisms as a possible strategy for enhancing their working performance. This work focuses on the Orthoglide 5-axis, a prototypal parallel robot for milling operation, characterized by linear-delta architecture with two further serial DOFs. Starting from a general theory formerly proposed by the authors, gravity compensation of the mechanism is analytically carried out. The statically balanced Orthoglide 5-axis can be obtained by installing on one leg a proper set of extension springs and a simple additional linkage. A feasible design solution for developing the device in practice is presented. The proposed balancing device can be implemented with minor modifications of the original robot design, thus appearing a profitable solution to be possibly extended to other machinery with similar architecture. Copyright {\copyright} 2014 by ASME.