Thanks, Wasnt expecing his forum to be so saturated with experts at this level on a UK site, Its very nice to see :)

In terms of my design, A plane is designed around engine and passangers, the same for a car in a nutshell. Well To make the design process easier I want to chosse all the size gear Ill need to get it off the ground. So I have found these rails...Are they good enough? If so I can take the dimensions and add them to solidworks so that the design is built around these giving me the size. Also motor mount dimension would be handy...Stepper motors to me seem to have the same mounting and bolt patterns and are just longer with power...Is this correct?

If so then again, the design process will be easier :)

Im also considering these rails also quite allot bigger but Im only 20 and am a student so funds are tight so I dont want to outgrow a machine right away... CNC 3D wings would be nice :D

What are your thoughts on going bigger?