From HacDC Wiki
To initially get started with the CNC mill, it's helpful to have a basic grasp of G Code. How better to get started with this than to begin playing.
To start, you'll want to fire up EMC2 with the proper configuration file. This can be done by using the icon on the desktop or by clicking the corresponding link on the quick launch bar on the top of the screen.
If the mill has been turned on and the right configuration file is used, you will hear the spindle briefly spin up.
Once in EMC2 you'll need to enable machine control of the mill. Begin by clicking the large red "X" button on the button toolbar within AXIS. After this button has been pressed, the power button directly beside it should become available to click. Upon pressing this "power" button, EMC2 / AXIS can be used to send commands to the mill.
Jogging the mill is a pain in the ass. One of the most helpful GCode commands you can use is "go to coordinate". To go to an X coordinate "zero" one would use "g0 x0", similarly to go to y0 one would use "g0 y0". This is especially helpful for moving the tooling out of the way to add a new piece to be milled or to make an adjustment. Subsequently, the tooling can be reset with "g0 x0" "g0 y0" "g0 z0"
Redbeard made some changes to the config file including resetting the initial home positions to "0 0 0 0" so that when the application starts up, it will leave the tool exactly where it is placed. While this isn't the behaviour we want long term, it's perfect for our current lack of limit switches. Additionally, the directive "no_force_homing=1" was added to get rid of pesky error messages (again, since we don't have limit switches for homing the device.)