keep monitoring the vibrations of the rotor if all these vibrations fall below the preset threshold or target values the rotor is considered balanced and the material removal is discontinued if material is removed at all the locations as indicated by the reduced influence coefficients and the vibrations are not below the preset thresholds the influence coefficients are recalculated based on data from the balancing of the rotor and final corrections are determined these final calculations are now based on the actual system performance and rotor behavior this self correcting procedure insures the achievement of precise balance limits in fig3 a cross sectional view of a rotor 90 is shown taken along a balancing plane the rotor has a substantial circular cross section with a radius r in a previous balancing operation a section 92 of sacrificial material has been removed the rotor is turned around its axis 26 counterclockwise tachometer 48 monitors the speed of the rotor and generates a pulse whenever point t passes the tachometer all angles are measured from point t the vibrations of the rotor are measured by sensor 28 the contour of the rotor is measured by topography sensor 32 the computer first calculates a coefficient for this zone by obtaining the values of b as defined in equation 1 and then reducing them to about 70 80 of their ideal values from the equation this influence coefficient has a magnitude b o expressed in laser shots and a phase angle l this angle indicates the angle of a point p at which material should be removed with respect to the reference point t of course since b o could range anywhere from one to several thousand it is not practical to remove.