Rweatherly,
Do you mean you can push the left side of the gantry away from you and pull the right side towards you? Or the left side can go up while the right side can go down? The first case calls out for dual screws, the second case calls out for better supported rails to reduce flex. (Actually professional rails will solve both, but we are talking JGRO here.)
I have been playing with dual leadscrews at the hobby level and it is a tough call between one motor with a belt verses twin motors. They both have their problems. Twin motors is the easiest, but needs constant fudging to keep them aligned, with either dual drivers or just parallel a single drive. A couple of missed steps on one motor (or a couple of power downs) and it will lock up.
One motor with a belt needs some way of aligning (squaring) the gantry, but should only need to be done once.
I still don’t know which I would recommend.
Steve |