We present a practical haptic model for a suturing simulator operating on spring-mass surface meshes. The model we use for suturing is a geometry-based model which includes the capability to form a knot. A method of extracting a tension value for a geometric suture is shown. Each reaction force that contributes to the haptic rendering of the tasks is analyzed, including contact forces, cutting forces, piercing, tissue resistance, collision forces between tools, and the cooperative forces inherent when the needle is passed from one hand to the other. The results are shown in a series of haptic force feedback plots over time..