There is a good read about CNC machine construction in
www.thermwood.com, namely "Three Dimensional Trimming and Machining" wich discuss about general CNC machine components and goes indepth on many hidden issues, mainly hard learned on practice and often overlooked when building the machine.
I have mentioned this book once but I believe it deserves another mention. Maybe a few ideas in Thermwood's documents will result benefical for the purposes of this book.
Konstantin