That is the point – this intended for a large delta, like mine. My carriages -- under normal conditions park at the top -- engage breaks (servos driven by an arduino) and printer powers down, if the breaks don't engage, the effector will fall down. If assuming normal conditions, we are assuming perfect knowledge in all cases -- I can't always assume that. If I have a hall effect sensor -- -- and I have 1 small tube and a large tube -- and a universal joint at the effector -- I can track small tube going in and out and know if I have to move the extruder axis up or down -- if you can bake that into the firmware - -great, but I plan on implementing it as a standalone feature -- like the piezo board. It will use the sensor to keep the rigid arm between the effector and the extruder carriage at a predefined distance -- it's actually fairly simple, your output of the hall effect sensor must be 512 -- you have a magnet at one end of the tube, and as the value decreases, that means the distance between the extruder and the effector is decreasing, so you move away -- which is up...as the value is increasing, which means the distance is increasing also, so you move the effector down
My delta is 1m tall with a 350mm bed, and my carriages don't fall when I turn my printer off.