A hybrid bit includes a fixed cutting structure and a rolling cutting structure. The fixed cutting structure includes a plurality of fixed cutting elements. The rolling cutting structure is coupled to the fixed cutting structure and includes a journal bore extending through the rolling cutting structure from a leading face to a trailing face, and a radially outer surface. The rolling cutting structure also includes a plurality of cutting elements extending from the radially outer surface of the rolling cutting structure.

A hybrid bit includes a fixed cutting structure and a rolling cutting structure. The fixed cutting structure includes a plurality of fixed cutting elements. The rolling cutting structure is coupled to the fixed cutting structure and includes a journal bore extending through the rolling cutting structure from a leading face to a trailing face, and a radially outer surface. The rolling cutting structure also includes a plurality of cutting elements extending from the radially outer surface of the rolling cutting structure.

A composite sintered body cutting tool, in which tungsten is reduced, is made of a TiCN-based cermet and WC-based cemented carbide. The cutting tool has an angle of less than 90 degrees formed by a rake face and a flank face. The rake face including a cutting edge contains WC-based cemented carbide including 4% to 17% by mass of iron group metal components with a remainder being WC. The thickness of the carbide is 0.05 to 0.3 times the thickness of the composite sintered body. The TiCN-based cermet which is a base body of the cutting tool includes 4% to 25% of the iron group metal components, less than 15% of W, 2% to 15% of Mo, 2% to 10% of Nb, and 0.2% to 2% of Cr. The cermet may contain iron group metal Co and Ni, where, Co/Co+Ni is 0.5 to 0.8.

A composite sintered body cutting tool, in which tungsten is reduced, is made of a TiCN-based cermet and WC-based cemented carbide. The cutting tool has an angle of less than 90 degrees formed by a rake face and a flank face. The rake face including a cutting edge contains WC-based cemented carbide including 4% to 17% by mass of iron group metal components with a remainder being WC. The thickness of the carbide is 0.05 to 0.3 times the thickness of the composite sintered body. The TiCN-based cermet which is a base body of the cutting tool includes 4% to 25% of the iron group metal components, less than 15% of W, 2% to 15% of Mo, 2% to 10% of Nb, and 0.2% to 2% of Cr. The cermet may contain iron group metal Co and Ni, where, Co/Co+Ni is 0.5 to 0.8.

A raise boring head for rotary boring in rock having a main body mountable at a drive shaft in which a mount face provides a supporting surface for a plurality of saddles that mount, in turn, respective roller cutters. At least one guide block is attached to the main body to project upwardly from the mount face and includes at least one guide face to facilitate the transport of cut material away from the mount face.

A raise boring head for rotary boring in rock having a main body mountable at a drive shaft in which a mount face provides a supporting surface for a plurality of saddles that mount, in turn, respective roller cutters. At least one guide block is attached to the main body to project upwardly from the mount face and includes at least one guide face to facilitate the transport of cut material away from the mount face.

A hybrid drill bit includes both fixed cutting elements and rotational cutting elements thereon. The fixed cutting elements are affixed to a bit body and define a peripherally-located fixed cutting structure disposed radially outward of the rotational cutting elements. The rotational cutting elements define a centrally-located counter-rotational cutting structure including two hemispherical counter-rotational cutting members mounted for counter-rotation with respect to one another on an axis generally perpendicular to a bit body rotational axis.

A hybrid drill bit includes both fixed cutting elements and rotational cutting elements thereon. The fixed cutting elements are affixed to a bit body and define a peripherally-located fixed cutting structure disposed radially outward of the rotational cutting elements. The rotational cutting elements define a centrally-located counter-rotational cutting structure including two hemispherical counter-rotational cutting members mounted for counter-rotation with respect to one another on an axis generally perpendicular to a bit body rotational axis.

A method for removing material with a bit includes rotating a bit in a first direction, changing the rotational direction and rotating the bit in an opposing second direction. Rotation of the bit in the first direction and rotation of the bit in the second direction both remove material.