Abstract
The distortion test which is made by bending the saw-blade tip upward is very accurate and practical, and therefore its sensitivity is studied on the basis of geometrical optics. A concentrated bending load is applied to the distorting center of the blade which is supported at the both ends. A surface of the blade in the above condition is then illuminated by a slit-light source and the images of light source formed by the surface are counted. When the blade is bent upward and in a concave position, the sensitivity increases linearly as the deflection is increased. The sensitivity takes maximum value at the optimum deflection, since the deviations of the normal direction of the surface caused by bending are larger in the neighborhood of the supporting points and smaller in and around the most deflected point. Although the width of the light sources used for the actual distortion test is not always narrow, high accuracies are obtainable, since above observations are carried out under the condition of the optimum deflection.
