The weighing system is achieved by means of a weighing table inserted in the main frame of the machine, and supported by 4 high precision electronic weight transducers; a digital amplifier/power supplier supplies power to the cells, appropriately filtered and adjusted, and amplifies the signal in proportion to the weight of the fibre. The software parameters, in particular the tare and full scale values, can be set using the display and keyboard. The anti-static belt which has a constant weight per surface unit, is installed on a steel frame, the walls of which are electrically heated and insulated to prevent condensation from forming. An important feature of the scale is that it is not affected by moderate pressure or negative pressure inside the weighing system, over a range of ±0.6 mbar. This is because the weighing table is not mechanically dependent on the scale structure. Material outlet is regulated by doffing rolls, each with its own motorized shaft, which have the task of metering, opening and distributing the fibre, along the entire width of the outlet.