The fracture mechanisms of brittle mode glass grinding are investigated using a high stiffness, single point abrasion system, where depth of diamond penetration and speed is controlled during the scratching of the glass. Normal and tangential forces on the glass are recorded and related to scratching speed, depth of cut, and types of damage observed for speeds between lOmm/s. and 14m/s. A reduction in these forces, but with increased levels of signal oscillation due primarily to chipping in front of the diamond ,is observed with in-creasing diamond speed. The presence of water in the abrasion zone acts to reduce brittle zone scratching forces in a highly speed dependent manner.