Quote Originally Posted by bigal999 View Post
Hi I have the supported rails already but I am not sure if z axis should be as close to the gantry of y axis or not
Albert
Don't waste the bits you've already bought, there are plenty of machines working to the full satisfaction of their owners using these rails. Mine for example. You can see the arrangement on my current build log.
If you're really worried there are designs using these rails mounted along the top and bottom of the gantry with the ballscrew behind, rather than with everything on the front like mine. One of the build logs on here has one I think, but it makes the Z axis more complex to build and the Y axis more difficult to align. You will also need to increase the height of the gantry above the bed. It's all about the compromises you're willing to make and the workshop facilities you have.