Johan_Ha:
If your stepper motor makes 2048 steps per revolution and you want a shaft that can perform exact degrees (360 steps per revolution), have a toothed belt wheel at your stepper motor with 128 teeth, a wheel at the shaft with 225 teeth. Ten steps will rotate the stepper motor 10/2048 revolutions. It will rotate the shaft 10/3600 revolutions.
Nice. Are those 128 teeth and 225 teeth components readily available online?