The dynamic disturbances of the deep-hole drilling process pose a great challenge. Especially spiralling, which causes holes with several lobes, can damage the workpiece irreparably. The causes for spiralling are not well explored yet, and it is important to analyze which conditions and process parameters can cause the spiralling. This article presents a simulation system for the idealized BTA (Boring and Trepanning Association) deep-hole drilling process. Methods of computer graphics allow the realistic modeling of the cutting edge and the workpiece. The simulation is able to calculate the sweep volume, cutting forces, and regenerative tool vibrations. It is also possible to generate the resulting geometry of the workpiece depending on the eigenfrequencies of the boring bar and on the process parameters. Thus, the pre-conditions for the spiralling can be analyzed.