Tools of grade S1P„ RD1O7 and RD11O with radiused cutting edges were tested to failure cutting slotted bars of EN9 at 600 f.p.m., 0.010 in/rev. feed and 0.10 in depth of cut. The results showed that there was a reduction in the frequency of early tool failure as compared with unradiused tips. A statistical analysis showed that there was no significant difference between the mean tool lives of the three grades.