How to build a DIY CNC Milling machine from scratch that can cut aluminium and steel.

My objective for this project was to design and build a CNC milling machine without the need for any machining of the parts. Ordinarily, building a mill requires a much bigger mill to get the axis surfaces flat and parallel.

By using aluminium tool plate (which is in theory premachined flat) and bolting the critical components rather than welding, it should be possible to avoid any machine work. After all, I'm building a mill because I don't have one!

Linear rails and ball screws are the cheap Chinese 20mm style that you can find on eBay etc.