A very important parameter of cutting machines is their rigidity. Unfortunately, there are not any infinitely rigid machines because there are not any infinitely rigid construction materials. However, you should always give priority to the problem of rigidity. Why would you increase the resolution of drives and apply precision roller screws, if under low load the head deviates up to the value that significantly exceeds the resolution of drives.

Nowadays there are aluminum profiles which are quite often used for the construction of light CNC machines. Admittedly, if you want to perform a simple unprofessional router, all you need is a saw for aluminum, a few screwdrivers and a drill, but such a machine does not represent much itself. The straight-line motion of the feeds depend on the accuracy of the profile pressing and the accuracy of the angles depend on the cutting saw. What is more, such structures are jointed with hundreds of bolts and thus they are vulnerable to loss of stability of the geometry.