A challenge in Multi-Pass Single Point Incremental Forming (MSPIF) has been the geometry control of formed components, especially on the base of the component where multiple stepped features are formed unintentionally. This work attributes the step formation to the rigid body motion during the forming process and develops analytical formulations to predict such motion during each intermediate pass. Based on this model, a new toolpath generation strategy is proposed to achieve a smoother component base by using a combination of in-to-out and out-to-in toolpaths for each intermediate shape. © 2011 CIRP.