Is One Screw Enough

[rocks101]

Hi all, we are a group of students working at building a cnc router to help us with our projects. I would like to know if one 5/8 ball screw will be enough to drive the gantry which is 4ft in length and 2 ft high, the gantry is sliding on dual 20mm Igus rails with their polymer bearings.The gantry's foot print is 12" and it has a trave of 36". I have posted a quick rendering of our design below. Any advice is greatly appreciated. Ps the gantry side are 1" thick aluminum plates, and most of the components other components are also aluminum.

Thank you