... holes and other drilling works Drill Rod/Tapered Drill Rod Taper drill rod is used for rock drilling, blasting holes and ... variety of taper angles, generally, the light duty rock drill usually use 7 taper or smaller taper angle, the ... heavy duty rock drill mainly use 11,12 taper angle. And the ... in bundles.(6)Productivity: 20000pcs / month MAXDRILL rock drill steel rod