Before I decided to build my own CNC machine I had seen a few bolt together machines on the internet, usually constructed using 80/20 aluminum extrusion. My write up describes my attempt at a completely DIY bolt together machine made from 25mm aluminum SHS, 50mm shelving brackets and lots and lots of gutter bolts.
Building the machine involved drilling and tapping about 400 holes (if I can still count) and assembling the machine over a 3 month period. I designed it mostly on the fly which lead to a few headaches, but in the end a machine that works quite well (if slowly and noisily). I go through each major component of the machine and describe how and why I would have changed it if I had followed the normal plan-design-build methodology.
I have tried two versions of stepper motor drivers and you can find the schematics for the DIY version on my site. The entire thing runs from a Linux PC running EMC2, check out a video after the break to see it in action and here are some photos of a few of my machined items.