Parametric Design of Scalable Mechanisms for Additive Manufacturing

Additive manufacturing allows a direct fabrication of any sophisticated mechanism when the clearance of each joint is sufficiently large to compensate the fabrication error, which frees the designers of cumbersome assembly jobs. Clearance design for assembly mechanism whose parts are fabricated by subtractive manufacturing has been well defined. However, the related standard for parts fabricated by additive manufacturing is still under exploration due to the fabrication error and the diversity of printing materials. For saving time and materials in a design process, a designer may fabricate a series of small mechanisms to examine their functionality before the final fabrication of a large mechanism. As a mechanism is scaled, its joint clearances may be reduced, which affects the kinematics of the mechanisms. Maintaining certain clearance for the joints during the scaling process, especially for gear mechanisms, is an intricate problem involving the analysis of nonlinear systems. In this paper, we focus on the parametric design problem for the major types of joints, which allows the mechanisms to be scaled to an arbitrary level while maintaining their kinematics. Simulation and experimental results are present to validate our designs.