Consider using a single motor driving all three screws with a belt so that all screws always stay in sync. It makes it much faster and easier to work on the machine because when you want to raise or lower the bed you can just pull on the belt and turn all three screws at the same time. Every time I have to do anything like level or zero the bed or work on the extruder on the Taz at the makerspace I am reminded of one of the reasons why I have such disdain for dual motors and screws in the Z axis. I have to step through multiple menu selections to jog the axis up or down. It's an annoyingly slow process.
One of the few design decisions I made when I started designing my printer that has persisted in the latest incarnation of the machine is belt driven Z screws. If I want to raise or lower the bed, I pull the belt or turn one of the pulleys by hand and it's done. No menus, no waiting for computers to boot, etc. I can do it with the power on (if the motors are disabled) or off.
In a CoreXY design, if the screws get out of sync the bed tilts and can be brought back into alignment relatively easily. In the "standard" cartesian design with the X axis lifted by the Z screws, loss of sync in the screws destroys the X axis alignment. If you've ever tried to align the axes in a printer for orthogonality you know that it is not a quick process, and having alignment depending on two screws that a child can turn with their fingers is a very poor design decision.
One of the few design decisions I made when I started designing my printer that has persisted in the latest incarnation of the machine is belt driven Z screws. If I want to raise or lower the bed, I pull the belt or turn one of the pulleys by hand and it's done. No menus, no waiting for computers to boot, etc. I can do it with the power on (if the motors are disabled) or off.
In a CoreXY design, if the screws get out of sync the bed tilts and can be brought back into alignment relatively easily. In the "standard" cartesian design with the X axis lifted by the Z screws, loss of sync in the screws destroys the X axis alignment. If you've ever tried to align the axes in a printer for orthogonality you know that it is not a quick process, and having alignment depending on two screws that a child can turn with their fingers is a very poor design decision.