I want to build a large printer (1200 mm x 1200 mm bed). At this stage, I'm favouring a flying gantry design where the print bed is stationary and the X and Z axes are fitted to a gantry which moves on a track system attached to the side of the print bed assembly.

The question I am trying to solve is: Should the Z axis assembly be moved by a system which has steppers on each side of the gantry like a Prusa, with the X-axis acting as the connection between the gantry sides as in this picture:

Prusa printer.jpg

or have the Z axis on a plate moved along the X-axis and only having one stepper on the Z-axis to move it up and down as in this picture:
Flying Gantry.jpg

I would add support brackets to the Prusa system for strength and rigidity. The only problem to overcome with the second design is to decide how much movement could be build into the Z-axis before it began to lose accuracy due to wobble.

What do you think?

Old Man Emu