Well here goes... Aluminium frame router design

[CharlieRam]

Also that Z axis design is bad news. Again check out threads and look at Z axis designs that put the rails on the front plate and bearings on rear. Your design is a constant length lever that won't even reach the bed surface and will give the same amount of flex whether it's at the bottom of top of it's travel. With the other design the lever length is variable dependent on material thickness or distance from tool.

Hi Jazz, is that Z axis any weaker the way I had it? I am struggling for room and didn't want to compensate by reducing my cutting area, I have gone back to Idea 3 but raised the rails on X. I would still like to use the fourth axis along X and this would allow that, giving me an effective work area of 150mm diameter by whatever length travel I decide on.
My X rails are 810mm apart, carriages are 250mm apart from outer dimension, Would I suffer from binding if I just had a central ballscrew or would you still recomend one on either side?
Thanks