I'm building an automatic warehouse system using three NEMA 17 stepper motor.
My problem is to move the motors with precision, since I do not have any kind of encoder on the motor and so I cannot know the position of the axes. I thought that the system could be similar to a 3D printer, since neither 3d printers have encoder on the motor.
Where can I find a sketch for Arduino of a 3D printer, to understand how they work? How do they move with such precision without any kind of sensor?