BENT SUB ASSEMBLY FOR DIRECTIONAL DRILLING

An adjustable bent sub assembly is provided comprising a tubular adapto r for connection with the stator of a downhole motor, a tubular adjusting ring for altering the angular offset of the assembly, and a tubular offset sub for connection with the bearing and bit assemblies. A tubular mandrel is positioned interna l of this stack of components. The mandrel is threadably connected at its upper e nd with the adaptor and at its lower end with the offset sub. The mandrel and ring have a spline connection. The ring and offset sub have disengagable dog clut ch means connection them. The mandrel is transversely bent at a point along its length as is the offset sub. The ring has an angled or canted bottom end fac e. The combination of bending the internal mandrel, bending the offset sub a nd canting the end face of the ring results in the effective or resultant bend point of the assembly being closer to its lower end.