In the manufacture at the factory, all installations, including a strip feeder and crushers, are certified and guaranteed to have the parameters indicated in the documents. But at the place of work, they are often subjected to artisanal modernization in order to increase the efficiency. At the same time, it does not undergo a check in the road laboratory, which is why for the increased speed of work you have to pay the error of cleanliness of sifting about 30-40%. This could be eliminated by calibration if not for one nuance.