Updated spec after current discussions:

1200x900 footprint area with approx 1000 x 800 cutting area
80x40x4mm steel box section frame with adjustable bed
Aluminium gantry made from a combination of 20mm/15mm plate either standard 6082 or ecocast for the bearing and guide plates
20mm Profile rail on x,y,z
**16/10 on x axis (running 2:1)**
16/10 on y axis
16/05 on z axis
250mm cutting depth on z
2.2kw chinese spindle

electronics (just ideas at the moment)

1 x nema 34 7.7nm running 2 x axis ball screws via a timing belt running dual 16/10 screws
1 x nema 23 3.1nm running y axis on 16/10 screw
1 x nema 23 3.1nm running y axis on 16/05 screw for better resolution

80v Leadshine Drives

75v PSU

Mach 3

How is this all sounding? are we on the right track :)

Design wise the gantry design is very similar to the one Jazz has posted on here before with interlocking aluminium plates (copying someones idea is the best form of flattery right? or is that plagiarism :P) anyway it looks an extremely solid design and I tend to make things over engineered so figured this was a good place to start.

With the y axis I was considering a direct drive using a coupler, all the other drives will use a belt to transmit motion, would it better to engineer it so the motors are all belt driven or would this make no odds?