I do CNC myself (BlackToe 2 x 4), and while it might be a good project to get RPi controlling a CNC, unless you have one already (RPi, that is), chances are that you won't be able to start your development anytime soon, like this year - orders keep getting pushed back. I use a controller product made by Planet CNC, a guy in Europe who make a fantastic standalone controller, with some pretty cool software. I am not affiliated with the product, BTW, I just use it and it works! And there is no need for a parallel port, as is the case with Mach3 controllers. It's a USB implementation, and that's IF you feel like hooking it up to a computer! You can dump your GCode onto a SD Card and let it rip, totally standalone.
http://www.planet-cnc.com/ Up to nine axes! Mindboggling!
Pic of my current CNC lathe. It could benefit from having a built in RPi console for CAM control. I need a little help...
I need some votes for my side business Gunhead.com in a grant contest.
As part of my future plans, I am going to incorporate a Raspberry Pi into a CNC lathe, among many other projects. IE: Paintball gun, CNC mill, CNC rotary table, CNC support community and more.
Today is the last day for voting in the contest (6/30/2012), so please help me out. (I am quite short of the goal, I started too late.)
Bottom right hand - log in & support.
Then search for "Gunhead" (without the quotes)
Send a vote my way.