Abstract: An adjustable bent sub for a down hole drill is disclosed consisting of a hollow housing and a hollow mandrel shaped to fit within the housing. A jam nut is positioned on the end of the mandrel to retain it within the housing by abutting a shoulder provided on the inner surface of the housing. A 1 degree off-normal face is machined on the shoulder and on the abutting face of the jam nut. By positioning the mandrel/jam nut assembly at different angular positions with respect to the housing, a linear deviation of 0 to 2 degrees is possible through the length of the sub.