Mosaic diamond drag bit cutter having a nonuniform wear pattern

A diamond cutter in a rotating drag bit comprising:

• a plurality of thermally stable, prefabricated polycrystalline diamond synthetic elements each having at least one end surface;
• a cutting slug formed of matrix material, said plurality of elements disposed within said cutting slug and said matrix material filling between said plurality of elements;
• a cutting face formed on said cutting slug and defined by a plurality of said end surfaces exposed on said cutting face;
• and
• a cutting edge formed on one side of said cutting face and including side surfaces presented by said polycrystalline diamond elements, said cutting edge including elements which wear at different rates thereby forming a cutting edge having a profile dependent upon the wear rate of the elements comprising said cutting edge.

A rotating drag bit comprising:

• a plurality of cutters, including at least two cutters of the type made from cutting elements embedded in a matrix material and presenting a plurality of end surfaces which define a cutting face;
• a first one of such cutters having elements which wear at a first rate;
• and
• a second one of such cutters having cutting elements which wear at a second rate different from said first rate.

A method of precussive drilling comprising the steps of:

• bonding a first layer of cutting elements to a precussive drill bit;
• bonding a second layer of such elements to said first layer;
• operating the precussive drill bit;
• orienting the bit to effect repeated striking of the cutting elements against an earth formation in a manner which compresses the cutting elements each time it strikes the formation.