The investigation of the dynamics of machining operations is especially valuable when it comes to finishing conditions, as vibrations during processing can significantly affect the surface integrity of the machined components. In this case, in fact, monitoring vibrations and different roughness parameters are extremely important, as they can even influence the mechanical behavior of the referred components. This work contains an investigation about the influence of the part geometry and some machining conditions on the vibration of the tool and on the surface integrity of the part in H13 hard turning. In this research, a conventional lathe was used, as well as a negative tool, whilst the influencing factors were the spindle rotation, feed, and also the position of the neck in machining. Vibrations results indicated the influence of feed regarding lower frequencies than 1,600 Hz. On the other hand, the roughness parameters showed some significant influence of the neck in machining. In view of the results obtained, it is concluded that although feed may surely impair tool vibration, the machined surface integrity is apparently more affected by part geometry. This approach can consistently contribute to the improvement of process planning involving the machining of hardened steels, because it indicates that additional workholding devices may be unavoidable depending on the requirements for surface roughness.