This video shows most of the details of building a "1/4 sheet" CNC router (650 x 1300 mm travel) capable of machining wood, plastic, aluminum, and steel to a certain degree.
Machine Specifications:
Working Area: 650 x 1300 mm (1/4 sheet plywood)
ER-11 air-cooled spindle driven by a 1.5 kW VFD
1610 ball screws (10 mm/rev) on the X and Y axes
1204 ball screws (4 mm/rev) on the Z axis
NEMA24 stepper motors on the X and Y axes
NEMA23 stepper motors on the Z axis
1:1 gear ratio on all axes
Dual sink motors on the Y axis with automatic power adjustment
The DM556 stepper driver runs at 48V for all axes.
Inductive distance sensors detect reversal points on all axes.
I'm currently using GRBL on an Arduino Mini (but I'm looking for a more advanced solution).
Since this machine is primarily designed for milling wood parts, the target accuracy is only +- 0.1mm. Since I don't have a way to mill surfaces for mounting linear rails, I don't see any reason to aim higher. Even though the surface finish on metal parts isn't the best, this machine is still useful for milling sheet metal and mounting brackets for future machine construction.
I hope this inspires others without machine tools to take on projects like this. I was amazed at the level of accuracy achieved with basic tools and commonly available materials.