Fig.4 shows the runout of CBN wheel after truing. Runouts ofthe wheel at the speed of 3000 min-l and 8000 min-’ are 2.3 pmp-p and 2.6 pm p-p, respectively. (In this measurement, the 5thpeak to valley point is picked up as a runout in order to avoid theeffect of noise.)Straightness of the ground workpieces are given in Fig.5. Theseworkpieces are ground under the condition of one pass in downfeed. The table feed rate is 320 mm/s and preset grinding depthof cut is 0.01 mm.6.4 mm and 2.4 mm pitch waves are obtained at 3000 min-land 8000 min-l, respectively. These pitch values agree with thecycles of wheel rotation.Average values of each wave are 0.04 pm and 0.08 pm. Theseamounts increase with the increase of wheel rotational speed.This means that runouts of wheels increase with the wheelrotational speed.