This paper describes a three-dimensional tool machining simulation system. The initial tool and the grinding wheels are integrated with the machine-tool. The application reads and interprets the CNC program code that controls the machine, it computes the positions and the motion of components and it translates the sequence of machining operations into boolean operations. The machining is computed for 2D sections and, later, a 3D model of the tool is reconstructed. The application is ready to yield tool visualization, it gives measurements on sections and it can show an interactive animation of the whole process. A novel aspect of the simulation is that it is able to deal with 6-axes machines, whereas most of previous work is limited to 3 and 4 axes machines. In addition, it allows to interrupt the machining process and to show partially machined tools. A major contribution is the fact that the boolean operations are performed in 2D and the 3D model is reconstructed from the cross sections, which provides user control on the resolution of the operations at a lowcost.