Shaping is a versatile process for machining gear teeth on complex monolithic components, which cannot otherwise be produced using other methods (like hobbing) due to geometric constraints. This paper presents a new model to accurately predict the chip geometry and cutting forces in shaping. Kinematics of gear shaping is modeled and verified. Cutter–workpiece engagement is predicted using a dexel-based geometric modeler, and refined by alpha-shape reconstruction. Varying rake and oblique angles are resolved along the cutting edges and used in three-dimensional force predictions. Simulated forces are shown to agree closely with those measured on a gear shaping machine.