PURPOSE: In the forward end of the holder used for the ball end mill etc, the slow away tip is detachably clamped for eliminating the extra grinding process of the tip when worn out.

CONSTITUTION: In a detachable slow away tip 5 in the forward end of a holder 2, a flat side 4 is provided in the end of the holder 2. On the other hand, a cutting blade C1 and C2, which possesses two dissimilar center B1 and B2 in its circular, is mounted in the slow away tip 5 and said cutting blade C1 and C2 is placed symmetrically in the form of sleight over a center A between the center B1 and B2. Then, the slow away tip 5 is detachably clamped by the clamp mechanism (con sisting of a bolt 6 for fixing the slow away tip 5 to a holder 2, a clamping metal 9 and a bolt for fastening tightly the clamping metal 9 on the surface of the slow away tip 5)