That’s a fair question. The key is in the fact that these are stepper motors. When they are energized they are in a statically bound condition. Think of it as the difference between a car with a manual transmission being in gear versus not being in gear. If you ever tried to push a car that was in gear, it’s almost impossible but in neutral, it’s much easier.
Good question. Consider the scenario the developers are trying to guard against. There is more risk in moving upward than downward. If the machine cannot determine the position of the head and it moves upward, there is a significant chance of damaging the nozzle, which many users here have reported. On the other hand, moving downward is less likely to cause damage, as most builds don’t end with the build plate at the bottom of its travel. However, when it does—as in my case—we clearly see that damage can occur.
To be clear, I’m not making excuses. Bambu could easily address this issue with a simple limit switch. These switches cost about $0.20 in volume and are straightforward to integrate. All that’s required are three wires to detect when the switch is closed.
