We propose a novel approach to dynamic simulation of grasps that overcomes di culties due to inconsistencies in the forward dynamics problem. The key idea in the paper is a minimalist model of the contact compliance and the use of this model in situations when the performance of the rigid body model is not satisfactory. Our general framework allows for on-line diagnostics that enable the automatic switching between models to maximize e ciency while avoiding ambiguous situations. We illustrate the basic ideas by simulating the dynamics of several whole arm grasps.