The overall concept of CNC work is fairly simple - cutting tools move along a preset path communicated through a computer to create parts, products or prototypes. From medium to large production runs, to ultra-high precision in highly detailed projects, this computerized approach offers many benefits to shop owners. When designing a CNC machined part, you may not have considered the type of machine the part will be machined on, but the complexity and type of geometry that can be designed into different types of CNC machines varies.The most common variation inherent in CNC work is the number of axes the router cuts the part in. Before knowing which CNC machine is the right choice for you, it is necessary to understand the basics by delving into its definition. The following details will introduce you to 3-axis and 4-axis CNC machines.