Tests were carried out with tools of grade S1P„ RD1841 RD110 and RD176 at 600 fpm cutting speed, 0.010 in/rev. feed and 0.10 in. depth of cut machining EN9 to determine their relative resistance to crater wear. The performance of the grades was in the ratio S1P-100, RD184-85„ RD110-56 and RD176-53, although with three out of the four corners tested the performance of RD184 matched that of S1P. During the tests RD184 was the only grade which had an edge radius and it is suggested that further tests should be carried out to determine whether this has any effect on cratering.