A rotary rock drill bit comprising a plurality of cutting elements or cutters mounted in the crown of the drill bit. Each cutting element comprises a thin planar layer of polycrystalline diamond bonded in the crown of the bit at a rake angle of between -10.degree. and -25.degree.. In another embodiment...http://www.google.com.au/patents/US4098362?utm_source=gb-gplus-sharePatent US4098362 - Rotary drill bit and method for making same
