Hi Omni - Design 2 is called a high rail design and is the best design for this job. Design 4 is a moving gantry design or some say a moving bridge or double bridge. FE is finite element. This is an engineering approach to calculate deflections and stresses. To calculate motors, powers and the rest is an engineering exercise that requires quite a bit of info on speeds and accelerations required, mass of parts and how you intend to move things. Quite a bit of work there before you can answer that... as a machine manufacturer you must have engineers doing this sort of thing? Cheers Peter

a 3.6m gantry has to be very stiff. Any design with a column will require it to be huge. The high rail design is naturally very stiff and then you make the gantry as stiff as needed.