A research program has been conducted for several years at CERT/DERA on a general methodology of control of mechanical flexible structures, and a facility named SECAFLEX has been built in-house to investigate experimentally the various issues of this topic. The goals and the design features of such a set-up are first discussed; the selected architecture - a two degrees of freedom flexible manipulator - is then presented with emphasis on the dimensioning of the actuators to get effective interaction between flexible modes and control. The problems due to in-joint friction and backlash which lead to include local torquemeters are investigated.