This is the first mill that I have built that is anything close to satisfactory. My first ever was built of timber and was too small. too slow, badly built and inaccurate. My second CNC router was built of MDF, and was four times larger than the first. However it was still slow and unfortunately MDF absorbs moisture and loses its stability and accuracy. Number three has been built with chunky aluminium channel (C-section) to my own design from lessons I learned with the previous two and is super robust.
So far, so good.
It has a respectable cutting area of 500mm x 400 mm.
Julius Ceasar's face cut in urethane foam.
Here is a video of number three in action. Here I am resurfacing a sacrificial cutting bet top, so that the material to be cut is perfectly in alignment with the Z axis. 19mm straight cut router cutting birch ply. 1mm pass at full speed (240mm/minute).