Observations on glass cutting by diamond

JSGT 1957 V41 T245-T258

The fundamental requirement in cutting glass is the production of a vertical fissure in the glass, the steps in the formation of which have been observed. The main obstacle to securing a clean cut is the formation of more or less horizontal cracks, which lead to splintering and, in severe cases, prevention of formation of the vertical fissure. If the diamond is accurately formed to a shape suggested by these considerations and accurately controlled in position and pressure, the horizontal cracks are of negligible size and there is no splintering, and the fissure becomes constant in direction and penetration.

P. R. Ord