Quote Originally Posted by Tinkerer View Post
I've noticed that a number of designs have placed Y axis screw on top of gantry (my design has it on side of gantry between rails). Placing it on top would help marginally with moving COG back. Is there an inherent preference for placing screw on top? Is my design inferior or not practical?
It makes sense to have the screw central to avoid twisting forces, for example mine is central but it's on the back. Sometimes people make a gap between two gantry beams and mount the screw in there.
You have the rails mounted on your gantry front face, moving these to top and bottom would also move the COG back. Things look great on a drawing but when it comes to building it you have to consider how to align everything so it's accurate accros the whole working area. If you go through that setting up stage in your mind, such as how to get the two rails on your gantry ligned up in all planes, then that might help steer the design.