Abstract: An adjustable angle instrument for high precision craftsmanship is configured from a pair of similar metal sector parts, each having a sector shape with a wide double flange along a straight edge. The two sector parts are accurately pivoted together in an apex region. Each flange is made to have accurate surfaces on its outer surfaces on which the instrument may be stood in a vertical position or laid horizontally on a flat surface such as a saw table. The flanges may be set to any angle between 45 and 90 degrees as indicated by a calibratable hairline cursor, and the angle may be captured by locking the two sector parts together by tightening a knurled brass knob. One of the sector parts is also provided with an edge which is accurately machined at 90 degrees relative to the flange and thus may be set to any angle between 0 to 45 degrees relative to the other flange, providing the instrument with a total range of 0 to 90 degrees.