On the Methods for measuring Straightness by Dial Gauge (2 nd Report)

Abstract

In the second report, in succession to the first report, the author regarded the surface to be tested as a series of straight lines or curves of the P th degree, and measured its straightness by connecting these lines successively. In the present paper, he mentioned its theory, errors of measurement and experimental results, and examined whether it is of practical use. The results are as follows : (1) In case of measuring straightness of the smooth surfaces such as mirrors, fine measurements may be carried out, but in case of the rough surfaces such as scraper-finished ones, the errors of measurement must be taken in calculation. (2) In case of measuring straightness of the surfaces which are long and rough, it is unnecessary to increase number of dial gauge in the former method, but neccessary in the latter method. (3) Straightness of the surfaces can be examined minutely by increasing the value of P.