Maybe someone can clear this up for me: What is the difference between the various types of mills? I have seen models with an X/Y table that has a head that only moves in the Z-axis. Most of the home-brew plans here are for gantry style mills where the surface is still and the head moves in all three axes. I have even seen one, I think on Cranky's site, that the table moved in the X-axis, but the head moved in the Y and Z axes.
Help!
What makes one design more favorable than the others, and why?
I plan to build a CNC mostly for cutting balsa for airplanes and possibly hardwood for signs.