The URC Underreamer Concentric is a Ring Bit System is composed of a removable outer ring that attaches to a driver and used with a down hole hammer and casing driver. Its purpose is to underream for casing installation.
The ring bit fastens to the driver bit with a press fit which prevents the ring bit from falling off. This system enables a driller to both drill and case simultaneously leaving only the ring in the hole when the job is completed. This ring portion of the bit is larger in diameter than the casing and has a smooth round outer surface.
Casing driving is done from the top by the Holte Casing Driver which turns on and off automatically. Straps, or reinforcement patches, are not needed on the welds. The welds do not get the same abuse as when casing is pulled down from the bottom, there is no threat of wearing through the shoe or driving it off the casing, leaving the down hole hammer free to do only drilling. The cuttings go up through slots in the center piece or bit driver which is also the stabilizer for the unit. To remove the ring bit, the casing driver is lowered so the casing sits on the ring portion. The down hole hammer is then pulled up while the casing driver is hammering, leaving only the ring and the casing in the hole.
The ring bit system is available in 6″ through 20″. Other sizes are available upon request. Customization available. Carbide or Diamond buttons available.