Stuart Batty Tools Angle Gauge One
Stuart Battys Angle Gauges are the only angle gauges in the world that set precise angles on both curved and flat surfaces with 40 different angles across three gauges, are100 accurate on 8" grinding wheels and all flat surfaces, and are accurate to within  1 degrees on 6" and 10" wheels. They actually work on grinding wheels by accounting for the tool thickness and using the tangent of the wheel to set the true cutting edge angle. Primary angles: 20 degrees, 25 degrees, 30 degrees, 40 degrees, 50 degrees, 60 degrees, 65 degrees, 70 degrees and 90 degrees. Complementary angles: 160 degrees, 155 degrees, 150 degrees, 140 degrees, 130 degrees, 120 degrees, 115 degrees and 110 degrees.