I'm thinking of doing some improvements to my CNC, one of the things I've noticed is that I do the majority of machining with reasonably thin material and hence the Z axis is at near maximum extension and there at it's least rigid position. Having the spindle fixed at a small extension from the gantry and moving the whole gantry up and down whilst being more complicated would seem to give better rigidity when machining "low" stuff, has anyone built a machine like this? I seem to remember seeing a pic of one somewhere but can't find it.