i e a reel of doctor blades 10 a 1 10 a 2 10 a 3 in accordance with the invention wherein each roll or blank of a doctor blade is mounted on a shaft which is provided with bearings in the vicinity of the feed out end of each doctor blade there is the measurement detector and cut off device in the vicinity of each feed out opening there is also the guide for the doctor blade more specifically fig2 shows doctor blade roll compartments d 1 d 2 d 3 each including a shaft 11 a 1 11 a 2 11 a 3 for a roll of doctor blades 10 a 1 10 a 2 10 a 3 bearings 12 a 1 12 a 2 mounted on the shaft 11 a 1 11 a 2 11 a 3 a feed out opening a 1 a 2 a 3 and a measurement detectors 13 a 1 13 a 2 13 a 3 arranged in connection with the feed out opening a 1 a 2 a 3 display 16 is arranged to display the measurement information produced from each compartment d 1 d 2 d 3 the central processing unit 100 interposed between the measurement device 13 and the display 16 operates as.