Planning my first CNC machine

[routerdriver]

I fear that you may be headed for difficulties with racking.If you were to place two steppers on the X axis and only one on the Z axis,I believe things might improve.Just imagine the forces on the workpiece if the cut is at one end of the table.It would be a lot closer to conventional thinking to have a full width table with the Z axis traversing the gantry.There is a downside in that the rather generous Z axis travel will encourage deflection of the Z axis with that rather generous amount of travel.In short,I would advocate that you consider a moving table machine with a full size table and a bit less headroom for rigidity.Obviously you have a greater understanding of your requirements than anybody else but I would ask you to imagine that you have been able to machine a part of some height and the end of the sequence is reached.With maximum retraction,can the cutter return to the home position without leaving a groove through the job?