I'm simply posting to attempt to contribute to this great community. I'm an avid RC aircraft hobbyist, and got into CNC machines to make things for that hobby. I started on a Shapeoko 2 and quickly found out it was garbage for anything but wood or plastic. I then set off on designing and building my own CNC router/mill. I wanted to be capable of cutting aluminum, so I when down the 'mill' path. It has cut some aluminum parts for me. I still need to get a better feel for the speeds and feeds. I also need a better spindle. I have a Sherline on there right now, and the case is kinda wimpy. I went with a gantry that moves up and down to solve what I perceived to be a weakness in most CNC router designs. Most simply have the gantry at a fixed height and move the Spindle down. When one does this, the rigidity suffers when the spindle is deployed downwards. My goal with this design here was to always keep the gantry behind the spindle, no matter the z-axis elevation. This also permitted quite a large increase in the z-axis capacity, relative to other gantry-type machines. The height of the side plates is what determines the z-axis capacity. Those plates I have there let me get about 10 inches of Z travel. I can stand plates up on end in the vise and machine features into the width of plates, for example.
Here's a video showing the machine moving in all axes:
Here are some pics:
This is the front of the machine. It has dual y-axis ballscrews, a single x-axis ballscrew, and the entire gantry moves up and down for the z-axis, so the Z has two ballscrews
Here is a side view of the machine, showing the gantry plate, and one of the y-axis ballscrews
Here's a view isometric showing the rear. One can start to see the dual z-axis ballscrews
Here's a straight-on view of the rear of the machine
A closeup of the x-axis, showing the headstock and its drive motor. That's a hobby brushless motor. I use a regualr helicopter ESC to drive it and an 18 V power supply. The pulleys from motor to spindle have a 1:2 ratio.
Here's a closeup of one of the z-axis ballscrews attachment points to the gantry.