The potential of nanotechnology depends on the controllable fabrication, integration, and stability of nanoscale devices. The creation of nanoscale features is essential for the fabrication of these devices. This paper describes the use of the atomic force microscope (AFM) to electro-machine nano-cavities on copper samples. Using known interelectrode gap, cavities as small as 200 nm in diameter were machined. A study was conducted to check the stability of the machined cavities. The results showed that cavities were stable within the period of time of the study (48 hours) in both air and deionized water environments. Feature destruction when occurred was found to be due to mechanical forces exerted on the sample by the scanning tip during the repeated scanning of the sample. The effect of electrostatic forces on the machining process was examined as well. It was found that the application of low frequency excitations (KHz range) resulted in undesirable cantilever oscillations and hence high frequency excitations (MHz range) are prefered.