New Build Log ... 2440 X 1220 X 300

[EddyCurrent]

'Forget it' is not a bad start but I'll stick my neck out and give it a go.

First it's a big machine for a first build, not impossible but just saying.
For spindles most use the 2.2kW or 3kW water cooled ones, make 2.2kW your minimum size.
20mm plate sounds good for a lot of the parts.
Not sure about using extrusion as I've no experience with it but a lot of people use it. Steel would be cheaper, for the frame at least, but you'd need to weld it.
Rack and Pinion is not the first choice but it might be okay for your size machine and application.
Ball screws are what you need for Y and Z. If you use these for X also, then one centrally mounted is a definite NO NO, you need two, one each side.
4th axis integration is fine, it just means the machine will be longer to accommodate it.
Hiwin or similar rails are much preferred over round supported rails but are more expensive.

Wait for more people to chip in then using that information knock up a drawing. Unless you already have some CAD software, 'Sketchup' is commonly used because it's free and easy to use
Look through the build logs and get ideas there. http://www.mycncuk.com/forums/253-DI...ter-Build-Logs