... in a variety of taper angles, generally, the light duty rock drill usually use 7 taper or smaller taper angle, the heavy ... of shank configurations and steel hex diameters for hand-held pneumatic drilling needs. (1) Steel grade: 95CrMo equivalent to SANDBAR ... hand held drill machine in Underground mining and for small hole drilling, equipped with small power rock drills, like air leg rock drills, hand ...