Micro machining is an emerging technology with extremely large benefits and equally great challenges. The push to develop processes and tools capable of micro scale fabrication results from the widespread drive to reduce part and feature size in many industrial and commercial sectors. For many micro machining applications, the technology of mechanical solid tool machining offers attractive merits as it can create truly three-dimensional and one-of-a-kind parts of extremely high resolutions without significant limitation of part materials. For mechanical solid tool machining, the control of three-dimensional motions between machines, tools, and parts to sub-micron level of precision is a perquisite to the realization of manufacturing at such fine scales. One important factor that contributes to the machining process accuracy is the overall size of the machine tool due to the effects of thermal, static, and dynamic stabilities. This paper will assess the technological benefits of miniaturization of machine tools in the context of machine stiffness and accuracy. It also presents the design philosophy and configuration of a 4-axis miniaturized vertical machining center of positioning accuracy of 4 to 10nm and a machine volumetric envelop less than (300mm)3, which is several thousand times smaller than traditional machining centers. A series of tests are discussed for performance evaluation of the miniaturized machining center in terms of the achievable finish and part form accuracy with respect to the process parameters and part geometrical complexity in 1-D, 2-D, and 3-D cases.