Planning my first CNC machine

[Sharp909]

I'm by no means an engineer but I find myself wanting to make my own CNC machine as I cant find anything within my budget that I feel confident will do the job I want. I want to make fairly simple aluminium parts with a 0.1mm or better accuracy. In my budget it's nearly all CNC router type machines but I see many comments about the rigidity of the gantry performing 2 motions. So I came up with this idea where the gantry is only providing Z motion with the spindle supported from both sides rather than the usual 1 side. The frame work is 160 x 80 aluminium extrusion and some 20mm Aluminium plate. I could also bury the base of this design in cement/epoxy granite. I plan to use a MASSO controller. Any advice welcome.