Method and apparatus for improving drill bit stability

A drill bit for drilling a borehole through a formation, said borehole having a borehole gauge diameter and a borehole wall, said drill bit having a drilling rotation direction, said drill bit comprising:

• a hard metal body having an end face;
• a plurality of PDC cutter assemblies disposed on said end face for engaging said formation, said plurality of PDC cutter assemblies including at least one final PDC cutter assembly axially and radially spaced from a central region point of said end face;
• a first metal body disposed adjacent said at least one final PDC cutter and having a first substantially smooth surface profiled to extend outwardly for substantially continuous sliding contact said borehole wall;
• a second metal body disposed laterally outwardly with respect to said center point of said end face, said second metal body having a second substantially smooth surface profiled to extend outwardly a distance less than a neighboring PDC cutter and being operable to engage said formation when said neighboring PDC cutter cuts too deeply into said formation;
• and
• a PDC member secured to said second metal body, said PDC member having a cutting edge and a frustoconical surface on said PDC member, said frustoconical surface having an angle greater than a rake angle of said second metal body.

A drill bit for drilling a borehole through a formation, said borehole having a borehole gauge diameter and a borehole wall, said drill bit having a drilling rotation direction, said drill bit comprising:

• a hard metal body having an end face;
• a plurality of PDC cutter assemblies disposed on said end face to form a line of PDC cutter assemblies, said plurality of PDC cutter assemblies including a final PDC cutter assembly disposed furthest from a center point of said end face;
• and
• a penetration limiter metal body disposed on said end face between two of said plurality of PDC cutter assemblies and being positioned along said line of PDC cutter assemblies, said penetration limiter metal body having an outer surface extending outwardly from said end face to a distance less than a distance said two of said plurality of PDC cutter assemblies extend outwardly from said end face, said outer surface of said penetration limiter metal body being operable to engage said formation when said neighboring PDC cutter cuts too deeply into said formation;
• and
• a PDC member secured to said penetration limiter metallic body, said penetration limiter metallic body extending outwardly from said end face further than said PDC member.