BOR MED HARDMETALINDLEG

摘要

For obtaining the maximum effectiveness from an axially extending drill with a hard metallic insert positioned on its drill end and a pair of axially extending oppositely spaced surfaces formed in its cylindrically shaped shaft, the ratio of the maximum diameter of its shaft to the dimension between the oppositely disposed surfaces is in the range of 1 : 0.7 to 1 : 0.8.