My first CNC machine build - Help and advise gratefully received

[Robin Hewitt]

Every time a noob designs their machine I pop up and say, "Do you really need 12" in the Z axis? It will give you a massive overhang because most of your work will be in the bottom 1 or 2 inches". They always swear blind they have stacks of 12" thick to do and carry on regardless.
Here you have 2 machines with monster Z travel and the bed fudged so they cannot use it. That single design facet tells you that you are looking at noob machines that have been fudged because they were designed badly.
Why not copy one of Jazz's recent machines, he is well past the stupid mistake phase. Why rip off problems when you can just as easily rip off something that works.