... ironstone, chert, abrasive rock etc. Including impregnated diamond core bit, surface-set diamond bit, reaming shells, casing bit, casing shoe ... to prevent premature wear of the matrix. Surface-Set diamond bits are primarily recommended for use in drilling ... minisite.productShow(); oProductShow.init( { 'aImgSrc': aBigImageSrc } ); } )(); Surface set diamond core bit NQ, HQ, PQ, NQTT, HQWL, T2, T6, NMLC ...