But there will always be some empty boxes no matter how tightly you calibrate the line. You're never going to have perfect tolerances in a mass production line

But there will always be some empty boxes no matter how tightly you calibrate the line. You're never going to have perfect tolerances in a mass production line like that. In fact, in this case, the scale is still a better solution than the blower, because not only do you need to not send out empties, but also incorrectly filled tubes.