Modern methods for testing flatness with the application of electronics and computers

Abstract

1. The testing of the flatness of large surfaces by means of manually-controlled autocollimators is at present a very labor-consuming operation. It cannot be used under workshop conditions, owing to its protracted setting and the large number of required calculations. 2. Precise measurements of linearity and flatness of surfaces at a height over 1 m above the floor can be made most efficiently by means of autocollimators which are provided with an automatic setting of their graduation lines and an output voltage fed to analog counting and recording instruments. 3. The most efficient but less precise device for testing the flatness of objects over 1.2 m in length located below 0.3 m from the floor consists of a rotating optical square, for instance, the one made by the Taylor Hobson Co. 4. In order to make the testing of flatness and associated repairs less expensive, it is recommended to establish in large engineering centers a material base consisting of the best possible measuring equipment with the application of electronics and computers, to organize short courses on modern testing methods, and to establish hiring depots with traveling crews for certifying, rescraping, and state testing standard straight edges and plates.