Hah, back to the drawing board...

1. Z axis travel is too short, I use following calculation:
(max tool stickout - min tool stickout) + max stock height + clamping height + safety
minimum: (35-10) + 25 + 10 + 5 = 65mm

2. To implement apron type chip guard, I need to extend Z axis overhang, and since arrangement was optimised to make tooltip as close as possible to the linear components, arrangement does not make sense any more - Y overhang needs to be extended for 60mm and axis travel is only 100mm

3. rigidity of X axis ballscrew shaft is 7x less than Z axis ballscrew, so there's no point in beefing up Y and Z if the percentage of their impact on the whole system rigidity is small. X axis rigidity can be improved by increasing shaft dia, but that raises inertia, so 2.7Nm/840gcm^2 stepper would work better than 400W/360gcm^2 AC servo, but that puts me in the no-feedback scenario, so there's no point in using servos on other axes...