This paper introduces the Quadriglide, a Schonflies motion generator module for 5-axis machine-tools. The targeted application is high speed milling of long aeronautic parts, in particular thin ones, instead of toxic and dangerous chemical milling. Quadriglide is described and its kinematics derived. Then, a preliminary optimization is done to achieve the best actuation stiffness in a prescribed workspace with large tilting angles (thetas = plusmnpi/4). Workspace plots of the optimized module are shown at the end of the paper.